0:00:25 > 0:00:28Inside this large, glass box,
0:00:28 > 0:00:32something extraordinary is happening.
0:00:32 > 0:00:35Food is being left to rot for eight weeks
0:00:35 > 0:00:37in our own unique laboratory.
0:00:39 > 0:00:42This is an investigation
0:00:42 > 0:00:47into nature's biggest and best recycler...
0:00:47 > 0:00:49..decay.
0:00:49 > 0:00:54And it's being done on a scale that has never been tried before.
0:00:54 > 0:00:59I'm Dr George McGavin. I'm a biologist with a particular passion for insects.
0:00:59 > 0:01:04The Rot Box detectives, Iona, Rosie,
0:01:04 > 0:01:07Ruaridh, Mram and Jamie
0:01:07 > 0:01:13are going to help me investigate the amazing world of rot and decay.
0:01:17 > 0:01:19'There's bacteria...'
0:01:19 > 0:01:20MACHINE BLEEPING
0:01:20 > 0:01:23Look at that. That really is smelly.
0:01:23 > 0:01:24'..flies...'
0:01:24 > 0:01:27I want to show you the fish. It's been completely eaten out.
0:01:27 > 0:01:29'..and mould.'
0:01:29 > 0:01:3220 or 30 species of fungus?!
0:01:35 > 0:01:40At Rot Box Detective HQ, I'm meeting up with the team.
0:01:40 > 0:01:44- Hi, team.- ALL: Hi.- How do you think we made the Rot Box?
0:01:44 > 0:01:47- Great difficulty.- Yeah, it was quite difficult actually.
0:01:47 > 0:01:51We wanted to make a typical kitchen and garden
0:01:51 > 0:01:54and fill it full of the sort of food you'd have
0:01:54 > 0:01:56if you were having a party.
0:01:56 > 0:01:59We wanted it quite warm, as if it was a hot summer's day
0:01:59 > 0:02:01and we wanted quite humid as well.
0:02:01 > 0:02:04So why do you think we did that?
0:02:04 > 0:02:06The bacteria would come
0:02:06 > 0:02:10because the hotter it is, like if you left a drink out
0:02:10 > 0:02:13for ages, it would go all warm and horrible.
0:02:13 > 0:02:17Exactly. The hotter it is, the faster things happen.
0:02:17 > 0:02:22- All organisms need some form of...? - Water.- Water, yes. Exactly.
0:02:22 > 0:02:26So the best conditions for bacteria and fungi
0:02:26 > 0:02:28are hot and sweaty, basically.
0:02:28 > 0:02:30The hotter it is, the faster things rot.
0:02:30 > 0:02:35This giant Rot Box has taken a team of engineers
0:02:35 > 0:02:39and scientists eight months to design and build.
0:02:39 > 0:02:42Conditions inside are now perfect for rot to begin.
0:02:45 > 0:02:48It's hot, humid and there's plenty of air
0:02:48 > 0:02:52so it doesn't take long for the mould to take hold
0:02:52 > 0:02:54and begin breaking down the food.
0:02:56 > 0:03:00By only the second day, there are dramatic changes inside.
0:03:00 > 0:03:04'It's really warm in here,'
0:03:04 > 0:03:06it's 25 degrees. That's like a warm summer day,
0:03:06 > 0:03:08so some things are drying out
0:03:08 > 0:03:12the chilli con carne is already growing a layer of mould.
0:03:12 > 0:03:16That shows there are fungal spores drifting around in the atmosphere
0:03:16 > 0:03:20and settling on food. Over here, the sandwiches
0:03:20 > 0:03:23which originally filled the box,
0:03:23 > 0:03:26up to the top, have sagged down to about half their height.
0:03:26 > 0:03:30- I think it's a fish. - I thought that was the fish.
0:03:30 > 0:03:32There's two fishes.
0:03:32 > 0:03:36- Eurgh, what's that?- Oh!- Where was it?
0:03:36 > 0:03:39- There. It's a dead mouse.- Eurgh!
0:03:39 > 0:03:40Disgusting!
0:03:40 > 0:03:44The Rot Box Detectives are intrigued and excited by what they see.
0:03:44 > 0:03:49It's time for them to start their own investigations.
0:03:49 > 0:03:52Who knows what an experiment is?
0:03:52 > 0:03:56It's an experiment when you judge something by something else
0:03:56 > 0:03:58and you see the difference maybe.
0:03:58 > 0:04:00Yeah, pretty close.
0:04:00 > 0:04:03If you have a question and you want to find the answer.
0:04:03 > 0:04:08Exactly. It's a controlled test that helps you to see
0:04:08 > 0:04:11if a question you ask is correct or not.
0:04:11 > 0:04:14So how would you design an experiment to investigate
0:04:14 > 0:04:16the effect of temperature on how fast things rot?
0:04:16 > 0:04:18Heat and cold.
0:04:18 > 0:04:21OK, so we have one hot environment and one cold one,
0:04:21 > 0:04:25which is a fridge and the airing cupboard. That's our variable.
0:04:25 > 0:04:28So what will we have to put in those two environments?
0:04:28 > 0:04:30- Something that will...- Rot.
0:04:30 > 0:04:33Yes! Something that will rot.
0:04:33 > 0:04:37So what sort of things do you think are going to rot easily?
0:04:37 > 0:04:41- Fruit and bread. - Fruit and bread, yeah.
0:04:41 > 0:04:46- Which do you think would grow the most mould?- I would say the bread.
0:04:46 > 0:04:47- Yeah.- Apples.- Apples, OK.
0:04:47 > 0:04:52Peppers, because in the Rot Box they were all really black and crispy.
0:04:52 > 0:04:56OK, so you've got all these things. What are you going to put them in?
0:04:56 > 0:04:59- Do you think you could put them in a glass box.- Yeah, OK.
0:04:59 > 0:05:03So you can each have two boxes, one will go in the fridge,
0:05:03 > 0:05:06the other in the airing cupboard where it's warm.
0:05:06 > 0:05:09We've got one variable, which is if it's hot or cold.
0:05:09 > 0:05:13- Everything else should be the same. Why?- Because it's a fair test.
0:05:13 > 0:05:15Absolutely. It has to be a fair test.
0:05:15 > 0:05:18If you don't have the same things, it's not fair.
0:05:18 > 0:05:22- How does bacteria get into it? - Good question.
0:05:22 > 0:05:24Well, bacteria is everywhere in the environment.
0:05:24 > 0:05:28We have bacteria all over our hands, even after you've washed them.
0:05:28 > 0:05:30There's bacteria all over this box,
0:05:30 > 0:05:33so the bacteria and the fungi are there,
0:05:33 > 0:05:35we just encourage them to grow.
0:05:36 > 0:05:40Our big Rot Box is also full of bacteria.
0:05:40 > 0:05:45In a matter of hours, they have started to do their work.
0:05:45 > 0:05:48The clearest signs of change are on the chicken.
0:05:48 > 0:05:50In just one day, our time lapse cameras
0:05:50 > 0:05:54show these blotches appearing on its skin,
0:05:59 > 0:06:03I've asked Dr Clare Taylor, a microbiologist, to join me
0:06:03 > 0:06:05and explain what's happening.
0:06:11 > 0:06:13Well, Clare, that chicken is beginning to look
0:06:13 > 0:06:15pretty discoloured.
0:06:15 > 0:06:16It smells a bit as well.
0:06:16 > 0:06:19There's beginning to be a slight whiff. What have you got on this?
0:06:19 > 0:06:22I tell you what I've got a UV light
0:06:22 > 0:06:25so we can take a look more closely at the surface.
0:06:25 > 0:06:28- Now you can't see it. - No, can't see anything.
0:06:28 > 0:06:29Take a look at that!
0:06:29 > 0:06:34It's glowing! So all these areas are glowing sort of blue.
0:06:34 > 0:06:40Exactly, so where you can see those glowing bits, that's bacteria.
0:06:41 > 0:06:45So even though we can't see them, bacteria are everywhere.
0:06:45 > 0:06:47They're all around us.
0:06:49 > 0:06:53'Now the team and I are going to make our own mini Rot Boxes.'
0:06:53 > 0:06:56LAUGHTER
0:06:56 > 0:06:59Right, two each. Pass them down.
0:06:59 > 0:07:02Two for you, two for you.
0:07:02 > 0:07:06Right, you can put whatever you want in the box,
0:07:06 > 0:07:11as long as both boxes are exactly the same.
0:07:11 > 0:07:14I thought it might be interesting to have one inanimate object,
0:07:14 > 0:07:17like a bolt or something.
0:07:17 > 0:07:21- Will that rot?- No.- Why won't it rot? - Because it's a metal object.
0:07:21 > 0:07:24It's metal, yeah, It isn't alive, is it?
0:07:26 > 0:07:27Fill your boxes!
0:07:44 > 0:07:48So in order for it to be properly scientific,
0:07:48 > 0:07:51we need to write down our names on a piece of paper, the date,
0:07:51 > 0:07:53and describe what we did.
0:07:53 > 0:07:55We have to say what the experiment was supposed to do,
0:07:55 > 0:07:59and what our predictions for the outcome of the experiment is.
0:07:59 > 0:08:02When we take our boxes out of the refrigerator
0:08:02 > 0:08:05and the airing cupboard, we then write down our results, OK?
0:08:05 > 0:08:08'I think the metal thing might get rusty,
0:08:08 > 0:08:13'because when I see the railings they mostly get brown from silver.
0:08:13 > 0:08:16'So I think it might rust a little.
0:08:16 > 0:08:19'I think there will be less mould in the cold one.
0:08:19 > 0:08:22'It might have a little bit of bacteria and a little bit of mould.
0:08:22 > 0:08:27'I think the pepper will rot the most, because when we went to see
0:08:27 > 0:08:31'the Rot Box, in the fruit bowl, the peppers were absolutely disgusting.
0:08:31 > 0:08:35'I don't think that the paper will go mouldy, but I think some
0:08:35 > 0:08:39'of the mould from the apple would probably go a bit onto the paper.
0:08:39 > 0:08:44'I think the potatoes will rot the quickest.'
0:08:44 > 0:08:48- I'm quite excited about this. - Me too, yeah.
0:08:48 > 0:08:52It'll be really good, this experiment. Really interesting.
0:08:52 > 0:08:56We might even find some undescribed species of fungi or bacteria.
0:08:56 > 0:08:59Who knows? It could happen.
0:08:59 > 0:09:01Back at the big Rot Box,
0:09:01 > 0:09:04the Detectives continue to be amazed by the world of decay.
0:09:06 > 0:09:10But will they see similar results in their mini Rot Boxes?
0:09:10 > 0:09:15Their experiment tests how temperature affects
0:09:15 > 0:09:18the speed of rot. They filled two boxes
0:09:18 > 0:09:22with exactly the same foods. The only variable is temperature.
0:09:22 > 0:09:27One box is in a hot place and one box is in a cold place.
0:09:27 > 0:09:29It's a fair test.
0:09:29 > 0:09:32They've recorded what they did, how they did it
0:09:32 > 0:09:35and what they think might happen.
0:09:35 > 0:09:37What will the detectives discover?
0:09:44 > 0:09:47Inside this large, glass box,
0:09:47 > 0:09:52something extraordinary is happening.
0:09:52 > 0:09:54Food is being left to rot for eight weeks
0:09:54 > 0:09:56in our own unique laboratory
0:09:59 > 0:10:01This is an investigation
0:10:01 > 0:10:05into nature's biggest and best recycler...
0:10:06 > 0:10:08..decay.
0:10:08 > 0:10:12And it's being done on a scale that has never been tried before.
0:10:13 > 0:10:19I'm Dr George McGavin. I'm a biologist with a particular passion for insects.
0:10:19 > 0:10:23The Rot Box detectives, Iona, Rosie,
0:10:23 > 0:10:26Ruaridh, Mram and Jamie
0:10:26 > 0:10:31are going to help me investigate the amazing world of rot and decay.
0:10:33 > 0:10:37'There are flies...'
0:10:37 > 0:10:40Well, there are simply too many flies in here.
0:10:40 > 0:10:43It's becoming quite unpleasant.
0:10:43 > 0:10:46'..bacteria...'
0:10:46 > 0:10:48- Oho!- Take a look at that. - It's glowing!
0:10:48 > 0:10:50'..and mould.'
0:10:50 > 0:10:54Even the hamburgers are wrapped up and they're covered in mould. Ooh!
0:10:54 > 0:10:56That might blow at any time.
0:11:00 > 0:11:02Pass them down. Two for you...
0:11:02 > 0:11:05'Four weeks ago, the Rot Box Detectives built their own
0:11:05 > 0:11:08'mini Rot Boxes so they could examine rot
0:11:08 > 0:11:12'more closely for themselves.'
0:11:13 > 0:11:18They wanted to see how temperature affects the speed of rot,
0:11:18 > 0:11:21so they designed a test, an experiment to find the answer.
0:11:24 > 0:11:30They had two boxes each and filled each box with the same things.
0:11:30 > 0:11:33To make the test fair,
0:11:33 > 0:11:38everything was the same except for one variable, which was temperature.
0:11:40 > 0:11:46They wrote down their hypothesis, what they thought would happen.
0:11:46 > 0:11:50I think there'll be less mould in the cold one than the hot one.
0:11:50 > 0:11:52It might have a little bit of bacteria.
0:11:57 > 0:12:01'Scientists often work in laboratories,
0:12:01 > 0:12:04'so we've come along to one to examine the results
0:12:04 > 0:12:06'of our four-week-old Rot Boxes.'
0:12:08 > 0:12:13I want you to meet a friend of mine called Patrick, who's a mycologist.
0:12:13 > 0:12:15That's an expert on fungi.
0:12:15 > 0:12:18Now we can only open the boxes because we're in a lab
0:12:18 > 0:12:22and because Patrick here is a specialist in fungi.
0:12:22 > 0:12:26He will tell us if there's anything harmful to us in these boxes.
0:12:26 > 0:12:30- I suspect there isn't anything that's that harmful.- It's unlikely.
0:12:30 > 0:12:34As long as we don't sniff or inhale them or eat them, touch them
0:12:34 > 0:12:37and put our fingers in our mouths, we should be fine.
0:12:37 > 0:12:41I know it's going to be very hard for you to resist,
0:12:41 > 0:12:43with your fingers touching things,
0:12:43 > 0:12:46so I think we should all put on gloves.
0:12:53 > 0:12:57OK, let's open the cold box first. So this is Ruaridh's one.
0:12:57 > 0:13:01Well, I can see there is a little bit of mould on the bread there.
0:13:01 > 0:13:02Penicillin probably.
0:13:02 > 0:13:07But everything looks as it would do when it's been fairly freshly made.
0:13:07 > 0:13:09None of it's gone mushy or soggy.
0:13:09 > 0:13:12We'll open the one that's been in the warm temperature.
0:13:12 > 0:13:15- Ooh! - CHILDREN: Eurgh!
0:13:15 > 0:13:19- That's very different, isn't it? - The bread has completely gone down
0:13:19 > 0:13:21to a kind of soggy mess.
0:13:21 > 0:13:24The apple looks like it's been poached or something.
0:13:24 > 0:13:29Ruaridh, you've at least shown what you thought was going to happen.
0:13:29 > 0:13:32There's more fungus growing in your hot box, but you were right
0:13:32 > 0:13:35about there being a little bit of fungus in your cold one.
0:13:35 > 0:13:38So this is Jamie's box.
0:13:38 > 0:13:42- Was the bread already this size? - I don't think it was.
0:13:42 > 0:13:43I think it's shrunken down.
0:13:43 > 0:13:46Why are the bananas pushed in?
0:13:46 > 0:13:49The fungus has taken the moisture out of the banana
0:13:49 > 0:13:52and used it for itself. It's shrunken right down.
0:13:52 > 0:13:56The fungi on my mushroom looks different than the other ones.
0:13:56 > 0:13:58OK, so we have a comparison.
0:13:58 > 0:14:03Fungi often changes depending on what part in their life cycle.
0:14:03 > 0:14:06Sometimes they can change colour in a few days.
0:14:06 > 0:14:10That one's plain white and that one's really bubbly.
0:14:10 > 0:14:14- Is that hard or soft, the mould on there?- Really soft.
0:14:14 > 0:14:16- It's breaking down. - Looks like a marshmallow.
0:14:16 > 0:14:19It is just like a marshmallow actually.
0:14:19 > 0:14:23That's the fungal mould that's growing through there.
0:14:23 > 0:14:27Would you say there's anything edible in any of the hot boxes?
0:14:27 > 0:14:28Let's have a look and see.
0:14:28 > 0:14:32No, it's all soft and horrible.
0:14:32 > 0:14:33Because we cut the oranges,
0:14:33 > 0:14:37the fungi and bacteria have got inside them and broken them down.
0:14:37 > 0:14:40But if you had a whole orange in there, it might not rot down.
0:14:40 > 0:14:44But you should still never eat anything in these experiments.
0:14:45 > 0:14:47Back at the big Rot Box,
0:14:47 > 0:14:50Patrick and I are staggered by what we discover.
0:14:52 > 0:14:55Now, this to my, Patrick,
0:14:55 > 0:14:58is one of the most amazing things I've ever seen.
0:14:58 > 0:15:01Look at it! I mean, that was a pile of cheese
0:15:01 > 0:15:05and tomato sandwiches that was up to the top of the box.
0:15:05 > 0:15:09- How many actual species of fungus are here?- Oh, at least 20 or 30.
0:15:09 > 0:15:12- Maybe more. - 20 or 30 species of fungus?!
0:15:12 > 0:15:16- Look at that. I mean, it's a solid mat.- Oh, yeah.
0:15:16 > 0:15:19There are the layers of sandwich.
0:15:19 > 0:15:22It's all the way through, it's completely through.
0:15:22 > 0:15:25There aren't many flies here, of course.
0:15:25 > 0:15:28Yeah, it was sealed in the box so the flies couldn't get in.
0:15:28 > 0:15:32Big contrast there to the fruit bowl which was left open.
0:15:32 > 0:15:37A couple of weeks ago, it was really covered in thick layers of fungus.
0:15:37 > 0:15:40- Look at the fly. - The flies have stripped it bare.
0:15:40 > 0:15:44The flies have gone in there, they've eaten the fungus,
0:15:44 > 0:15:47eaten the spores and really just recycling the fungi.
0:15:47 > 0:15:50Moulds are masters of decay.
0:15:50 > 0:15:53They're a form of fungi, the most versatile
0:15:53 > 0:15:56and important decomposers on the planet.
0:15:56 > 0:15:59Fungi can grow on almost anything.
0:15:59 > 0:16:05In our box, moulds are attacking our fruit and vegetables
0:16:05 > 0:16:10and spread by releasing spores into the air which are like seeds.
0:16:10 > 0:16:12They find new places to settle and grow,
0:16:12 > 0:16:17overwhelming everything in their path, even our meat.
0:16:19 > 0:16:24There are up to 500 spores in every cubic metre of air in your home.
0:16:24 > 0:16:28But they're so small, you can only see them with a microscope.
0:16:33 > 0:16:34Whoa.
0:16:34 > 0:16:37It looks like snow.
0:16:40 > 0:16:44It looks like the fluff on my teddy bear or something like that.
0:16:44 > 0:16:46The white looks like the Antarctic.
0:16:49 > 0:16:52Now this microscope only magnifies things about 100 times.
0:16:52 > 0:16:54But in the Rot Box,
0:16:54 > 0:16:59we had a microscope that could magnify stuff by 7,000 times.
0:16:59 > 0:17:03I want you to take a look at some of the fungi we filmed there.
0:17:05 > 0:17:07This is the kind of mould you might find in your bread,
0:17:07 > 0:17:10magnified by 7,000 times.
0:17:11 > 0:17:16The thread-like stalks are ten times finer than a human hair.
0:17:17 > 0:17:22The fluffy ball shapes at the top are where the spores live.
0:17:22 > 0:17:24Much like dandelion seeds,
0:17:24 > 0:17:29the spores are released into the air and carried to new places to grow.
0:17:30 > 0:17:34You might not always be able to see it, but mould is everywhere.
0:17:34 > 0:17:39Your house alone may contain an unbelievable 1,000 different
0:17:39 > 0:17:41types of mould.
0:17:41 > 0:17:42Patrick, thanks very much.
0:17:42 > 0:17:47It's been a real thrill to be able to use your lab and your expertise.
0:17:47 > 0:17:50- I'm sure we've learned quite a lot, haven't we?- Yeah. - So thank you very much.
0:17:55 > 0:18:00Back inside the big Rot Box, mould continues to astound and amaze.
0:18:01 > 0:18:04The Rot Box Detectives have grown their own fantastic fungi
0:18:04 > 0:18:06in their mini Rot Box experiments.
0:18:09 > 0:18:13They found that there was more mould in the hot box than the cold box.
0:18:15 > 0:18:19This is because mould grows faster in warm conditions
0:18:19 > 0:18:22than in cold conditions.
0:18:22 > 0:18:24They prove that their hypothesis,
0:18:24 > 0:18:28which is what they thought might happen, was correct.
0:18:42 > 0:18:44Inside this large, glass box,
0:18:44 > 0:18:48something extraordinary is happening.
0:18:48 > 0:18:51Food is being left to rot for eight weeks
0:18:51 > 0:18:56in our own unique laboratory.
0:18:57 > 0:19:04This is an investigation into nature's biggest and best recycler...
0:19:04 > 0:19:05decay.
0:19:05 > 0:19:10And it's being done on a scale that has never been tried before.
0:19:10 > 0:19:12I'm Dr George McGavin.
0:19:12 > 0:19:16I'm a biologist with a particular passion for insects.
0:19:16 > 0:19:23The Rot Box detectives, Iona, Rosie, Ruaridh, Mram and Jamie
0:19:23 > 0:19:29are going to help me investigate the amazing world of rot and decay.
0:19:34 > 0:19:36'We'll see flies...'
0:19:36 > 0:19:40The burgers that were opened are riddled with maggots.
0:19:40 > 0:19:41'..mould...'
0:19:41 > 0:19:45It's almost a battle zone in your bread bin.
0:19:45 > 0:19:47'..and bacteria.'
0:19:47 > 0:19:50I wonder how many bacteria are on that.
0:19:52 > 0:19:57At Rot Box Detective HQ, we're investigating some really bad smells.
0:19:57 > 0:19:59I've got a challenge for you.
0:19:59 > 0:20:04How can you tell if food is safe to eat, if it's off,
0:20:04 > 0:20:06without actually tasting it?
0:20:06 > 0:20:07Because of the smell?
0:20:07 > 0:20:09Smell is a very good clue.
0:20:09 > 0:20:14Maybe from its looks, because sometimes you see the bread is white,
0:20:14 > 0:20:21and sometimes it's green. So you can spot the difference between them if it's rotten or not.
0:20:21 > 0:20:24Mm-hm. If a food smells funny, or off,
0:20:24 > 0:20:29or if it looks peculiar, that's a really good warning sign, isn't it?
0:20:29 > 0:20:35Well, I've brought some items along for you to smell. See if you think they're off.
0:20:35 > 0:20:36Here's the first one.
0:20:36 > 0:20:38Cheese. What do you think of that?
0:20:38 > 0:20:41- That's all right.- Urgh!
0:20:41 > 0:20:42I don't think it's off.
0:20:44 > 0:20:47It's strong but I wouldn't say it's off.
0:20:47 > 0:20:50It's not off, but it smells really, really strong.
0:20:52 > 0:20:55Yeah, it's strong, but it's not a lot to...
0:20:55 > 0:20:59Let's try... Now, don't smell this one, OK?
0:20:59 > 0:21:02It's mouldy bread, so you don't have to smell it.
0:21:02 > 0:21:04Very mouldy, isn't it?
0:21:06 > 0:21:07If you found that in your bread bin,
0:21:07 > 0:21:11- you wouldn't want to put that in your toaster, would you?- No,
0:21:11 > 0:21:13you'd be mad to eat that.
0:21:14 > 0:21:17Dark green, yellow...
0:21:17 > 0:21:19Yellow in the bottom...
0:21:19 > 0:21:22It's mostly green on the top.
0:21:22 > 0:21:23Eugh!
0:21:23 > 0:21:27It looks like a sponge you use for washing the dishes!
0:21:27 > 0:21:29HE LAUGHS
0:21:29 > 0:21:31Now, I've got an extra special treat -
0:21:31 > 0:21:35I've brought you your lunch. Have a good smell of that. That's fish.
0:21:35 > 0:21:36Urgh!
0:21:36 > 0:21:39That's disgusting!
0:21:41 > 0:21:43Oh! Ho, ho!
0:21:43 > 0:21:44HE CHOKES
0:21:44 > 0:21:47That is...
0:21:47 > 0:21:49Eugh!
0:21:49 > 0:21:52THEY LAUGH
0:21:52 > 0:21:54Anyone else want an extra smell?
0:21:54 > 0:21:56THEY LAUGH AND SHRIEK
0:21:58 > 0:22:00The reason this smells SO bad
0:22:00 > 0:22:02is it's loaded with bacteria
0:22:02 > 0:22:04that have all been developing in there,
0:22:04 > 0:22:07and they're producing toxins and gases,
0:22:07 > 0:22:10and that really dreadful smell
0:22:10 > 0:22:13is warning you that that's really off. You wouldn't eat this
0:22:13 > 0:22:16in a million years, would you?
0:22:16 > 0:22:21- If it was the last thing on earth. - If it was the last thing on earth... - GIGGLING
0:22:24 > 0:22:29There is an overpowering stench inside the giant Rot Box, too,
0:22:29 > 0:22:32as the bacteria breaks down the food
0:22:32 > 0:22:34which has now been decaying for two days.
0:22:34 > 0:22:39Let's take a closer look at them under the microscope.
0:22:39 > 0:22:43This bacterium, Pseudomonas, magnified 7,000 times,
0:22:43 > 0:22:48is the most common type of food-rotting bacteria.
0:22:48 > 0:22:53There are as many as a trillion individual bacterial cells
0:22:53 > 0:22:56in this sample alone.
0:22:56 > 0:22:59We can't see bacteria without a microscope,
0:22:59 > 0:23:02but they're absolutely everywhere.
0:23:02 > 0:23:06They're the most common agent of decay on the planet.
0:23:06 > 0:23:09They're the first to attack dead animals
0:23:09 > 0:23:12because they're already living on them.
0:23:12 > 0:23:15All creatures carry bacteria.
0:23:15 > 0:23:20These bacteria were on our chicken when it was alive,
0:23:20 > 0:23:22and now that it's dead,
0:23:22 > 0:23:25they've quickly begun to decompose its flesh.
0:23:33 > 0:23:39- Who can tell me something about bacteria?- They're small.- Very small.
0:23:39 > 0:23:43- You need a microscope to see them. - You do need a microscope.
0:23:43 > 0:23:46In fact, here is a teaspoonful of soil.
0:23:46 > 0:23:49How many bacteria do you think are in that teaspoonful of soil?
0:23:49 > 0:23:54- Over a million?- There are 40 million bacteria in that amount of soil.
0:23:54 > 0:23:57It's hard to see them, but it's easier to see what they do,
0:23:57 > 0:24:02and on here, I've got a film of a chicken that we put in the Rot Box.
0:24:02 > 0:24:07Now, look at this. Watch this.
0:24:07 > 0:24:10- THEY ALL GASP - What's going on there?
0:24:10 > 0:24:12- It's blowing up.- Like a balloon.
0:24:12 > 0:24:14It's blowing up like a balloon.
0:24:14 > 0:24:17That was a fresh chicken, a completely fresh chicken,
0:24:17 > 0:24:21but any piece of fresh meat has bacteria on it,
0:24:21 > 0:24:26and because we just left that in the open, the bacteria grew and grew.
0:24:26 > 0:24:29Some of these bacteria are really quite hazardous,
0:24:29 > 0:24:32so if you ate uncooked meat, you'd be quite ill.
0:24:32 > 0:24:36So, with all these bacteria around, how can you make food safe?
0:24:36 > 0:24:38- You can refrigerate it.- Yeah.
0:24:38 > 0:24:42- You could cook it and then put it back in the fridge.- Absolutely.
0:24:42 > 0:24:47- What do organisms need to grow? - Water!- Water, yeah. OK.
0:24:47 > 0:24:51So you could dry it, you could freeze it,
0:24:51 > 0:24:54you could heat it up, if it's cooked.
0:24:54 > 0:24:59- Would cooking a chicken make it safe for ever?- ALL: No.- No, it wouldn't.
0:24:59 > 0:25:03- Because it would eventually rot, as well.- Yeah.
0:25:03 > 0:25:08So it's all about slowing down the bacterial growth, isn't it?
0:25:08 > 0:25:12In the Rot Box, we had the ideal environment for growing bacteria.
0:25:12 > 0:25:15It was hot, it was humid, and there was air,
0:25:15 > 0:25:18so bearing that in mind, I want to set you a challenge.
0:25:18 > 0:25:21I'm going to divide you into two teams
0:25:21 > 0:25:25and you're going to a supermarket to find different foods
0:25:25 > 0:25:27that have been preserved in different ways. OK?
0:25:27 > 0:25:30- Are you up for that?- ALL: Yes!
0:25:42 > 0:25:44What's in that? That's good.
0:25:44 > 0:25:46CHILDREN CHATTER
0:25:46 > 0:25:52- So what shall we get?- We need something sealed, tinned, boxed...
0:25:52 > 0:25:54- I think it looks good.- Yeah.
0:25:59 > 0:26:02Frozen - ah, here we are!
0:26:02 > 0:26:04Oh, cans! Yeah.
0:26:04 > 0:26:06On the hunt for baked beans.
0:26:06 > 0:26:08There we are. Right.
0:26:08 > 0:26:10Done!
0:26:11 > 0:26:14Let's start with the girls' team. What have you got?
0:26:14 > 0:26:20- Vacuum-packed coffee.- And that's preserved because...?- No air.
0:26:20 > 0:26:22There's no air, so that'll slow the bacteria down.
0:26:22 > 0:26:26- What else have you got?- Dried mango.
0:26:26 > 0:26:28There's no water in it so, again,
0:26:28 > 0:26:31that'll stop the bacteria growing. Anything else?
0:26:31 > 0:26:38- Gammon. There's no air and it was cold. It was in the fridge.- OK.
0:26:38 > 0:26:41It probably has preservatives in it, as well.
0:26:41 > 0:26:44They add preservatives to make food last longer.
0:26:44 > 0:26:47Good work, girls. Let's see what the boys have got.
0:26:47 > 0:26:52- We've for croutons, which we bought because they were dry.- Absolutely.
0:26:52 > 0:26:55Dry as a bone in there. OK. What next?
0:26:55 > 0:26:58Olives, cos they're in water,
0:26:58 > 0:27:03and when they're in water, we thought the bacteria would slow down
0:27:03 > 0:27:07because we've never seen rotten olives before.
0:27:07 > 0:27:11Water's not going to be good because that'll encourage bacterial growth.
0:27:11 > 0:27:16It's actually olive oil in here, and it's been vacuum-packed as well,
0:27:16 > 0:27:21so if you keep that shut, it should stay fresh - or not rot -
0:27:21 > 0:27:22for quite a long time.
0:27:22 > 0:27:26We got baked beans, because they're tinned
0:27:26 > 0:27:31and it would be harder for the bacteria to go in
0:27:31 > 0:27:34because it's tinned.
0:27:34 > 0:27:37So, unless you open that can,
0:27:37 > 0:27:39it'll probably stay fresh for a very long time.
0:27:39 > 0:27:44I am amazed that nobody picked frozen food,
0:27:44 > 0:27:47one of the commonest ways of preserving food.
0:27:47 > 0:27:51It's so cold no bacteria will grow in there. Or, if they do,
0:27:51 > 0:27:54it'll be very, very slow indeed.
0:27:54 > 0:27:57All these are brilliant techniques at slowing down
0:27:57 > 0:28:01the growth of bacteria - you exclude water, you keep it cold
0:28:01 > 0:28:04or you exclude air - so well done, everybody.
0:28:08 > 0:28:13We can often tell when food isn't good to eat by looking at it
0:28:13 > 0:28:15or smelling it.
0:28:15 > 0:28:17It's easy to see mould at work.
0:28:17 > 0:28:19We can't see bacteria,
0:28:19 > 0:28:24because they're tiny organisms that can only be seen using a microscope.
0:28:24 > 0:28:28But we can see the effects of what we do,
0:28:28 > 0:28:32and we can smell the gases they produce when they're attacking food.
0:28:32 > 0:28:34This should warn us not to eat it.
0:28:34 > 0:28:38Bacteria are everywhere, and are already on foods like meat and fish
0:28:38 > 0:28:40when you buy them.
0:28:40 > 0:28:44They are the most common agents of decay on the planet.
0:28:51 > 0:28:54Inside this large glass box,
0:28:54 > 0:28:58something extraordinary is happening.
0:28:58 > 0:29:01Food is being left to rot for eight weeks
0:29:01 > 0:29:04in our own unique laboratory.
0:29:07 > 0:29:11This is an investigation into nature's biggest
0:29:11 > 0:29:15and best recycler - decay.
0:29:15 > 0:29:20And it's being done on a scale that has never been tried before.
0:29:20 > 0:29:22I'm Dr George McGavin.
0:29:22 > 0:29:26I'm a biologist with a particular passion for insects.
0:29:26 > 0:29:30The Rot Box detectives - Iona, Rosie,
0:29:30 > 0:29:33Ruaridh, Mram and Jamie -
0:29:33 > 0:29:36are going to help me investigate
0:29:36 > 0:29:40the amazing world of rot and decay.
0:29:44 > 0:29:46'We'll see flies...'
0:29:46 > 0:29:47Oh. Oh-hoo!
0:29:47 > 0:29:49Look at this.
0:29:49 > 0:29:51'..mould...'
0:29:51 > 0:29:53Ah! That's incredible.
0:29:53 > 0:29:55'..and bacteria.'
0:29:57 > 0:29:59The bacteria have been hard at work.
0:30:02 > 0:30:08At Rot Box detective HQ, we're discovering more about bacteria.
0:30:08 > 0:30:11Now, who can tell me something about bacteria?
0:30:11 > 0:30:15- There's some good bacteria and some bad bacteria.- True.
0:30:15 > 0:30:19- They're absolutely everywhere. - That is completely correct.
0:30:19 > 0:30:22I went out to the garden earlier and I collected some rainwater.
0:30:22 > 0:30:28There are one million bacteria just in that little spoonful there.
0:30:28 > 0:30:32- One million!- Wow.- In there.
0:30:32 > 0:30:35Now, the one thing about bacteria, of course, is, as you said,
0:30:35 > 0:30:38there's good and bad ones.
0:30:38 > 0:30:41What would happen if a bad bacterium had got inside you?
0:30:41 > 0:30:45- You'd get a tummy bug.- Absolutely.
0:30:45 > 0:30:48How do you think the bacteria get inside you?
0:30:48 > 0:30:53If you eat something but before you ate it, you didn't wash your hands.
0:30:53 > 0:30:58Absolutely right. That is the commonest route to get internal infections,
0:30:58 > 0:30:59internal bacteria.
0:30:59 > 0:31:03Now, I've got a very smart trick that will show us
0:31:03 > 0:31:08how easy it is to transfer bacteria from person to person to person.
0:31:08 > 0:31:09OK?
0:31:11 > 0:31:15Now, we can't see bacteria on our skin without very special equipment,
0:31:15 > 0:31:18but I can show you how they spread around.
0:31:18 > 0:31:23'I'm going to show the team how easy it is to spread bacteria
0:31:23 > 0:31:28'by using this special cream that glows under ultraviolet light.'
0:31:28 > 0:31:32You can't see it there, yeah? OK?
0:31:32 > 0:31:36- But if I now put this under my hands, you can see...- ALL: Ohhh!
0:31:37 > 0:31:41..it's everywhere, OK?
0:31:41 > 0:31:44Now, hold your hands up, Iona. Clean? In the ultraviolet. Other side.
0:31:44 > 0:31:46Completely clean.
0:31:46 > 0:31:48Now, if I shake your hand...
0:31:48 > 0:31:52Hello, nice to see you! And now you put your hand under the there.
0:31:52 > 0:31:53ALL LAUGH
0:31:53 > 0:31:56Whoa! Now, if you shake hands with Ruaridh...
0:31:59 > 0:32:02Hello! Shake hands. And underneath there - let's see.
0:32:02 > 0:32:09Ew! Yes, it's spread, from me to you to you, right?
0:32:09 > 0:32:12Very, very easy.
0:32:12 > 0:32:15Now, imagine this was bacteria. OK?
0:32:15 > 0:32:20I'm going to squidge it in your hands, OK, and rub that all in.
0:32:20 > 0:32:24'Some bacteria can cause disease and make us feel unwell.
0:32:24 > 0:32:26'You might know them as germs.
0:32:26 > 0:32:30'They can get onto my hands when we sneeze or cough into them, or when we use the toilet.
0:32:30 > 0:32:34'That's why it's important to wash your hands properly.
0:32:34 > 0:32:37'I'm testing how well Jamie and Rosie wash their hands.'
0:32:37 > 0:32:41Now, let's just check under the ultraviolet light,
0:32:41 > 0:32:43see how glowing your hands are.
0:32:43 > 0:32:45Ooh, yes!
0:32:45 > 0:32:50Come on, Jamie. Squidge round. Oh, yes! Oh, yeah.
0:32:50 > 0:32:52Go wash your hands.
0:32:52 > 0:32:55Let's see how well they do.
0:32:57 > 0:33:01- Ah-ha! Right, are your hands washed? - Yes.- Let me inspect them.
0:33:01 > 0:33:02Do the old test.
0:33:02 > 0:33:06Oh, yes, now if I was a parent, I'd say, "That's very good.
0:33:06 > 0:33:08"Very good. Very clean." But is it?
0:33:08 > 0:33:11Rosie, stick your hands under the ultraviolet.
0:33:11 > 0:33:13- Oh-hoo-hoo! Eugh! - ALL: Eugh!
0:33:13 > 0:33:14Not so good.
0:33:14 > 0:33:18It's all on your fingernail. It's all over your thumb.
0:33:18 > 0:33:21Oh, yes, not so clean, but not bad. OK?
0:33:21 > 0:33:23Jamie, stick your hand in there, son.
0:33:23 > 0:33:25Let's see what we've got on yours.
0:33:25 > 0:33:28ALL: Eugh!
0:33:28 > 0:33:33Oh, yeah. I think Rosie won that one. Yeah, definitely, yeah.
0:33:33 > 0:33:35It's on all your fingernails,
0:33:35 > 0:33:39over the front and back of your hand, in the creases of your thumbs and fingers.
0:33:39 > 0:33:41Not good enough.
0:33:41 > 0:33:46So you see how you think you've washed your hands carefully enough,
0:33:46 > 0:33:50but actually to wash your hands really carefully and properly to remove bacteria
0:33:50 > 0:33:51it's quite hard.
0:33:51 > 0:33:56The correct way to wash your hands, of course, using soap and hot water
0:33:56 > 0:33:59is to put the soap there, rub, rub, rub, right?
0:33:59 > 0:34:02Both sides and then interlock your fingers like this
0:34:02 > 0:34:06and then do the backs of your fingers like that,
0:34:06 > 0:34:07then you do your thumbs, yes?
0:34:07 > 0:34:10And then your thumbs like that, OK?
0:34:10 > 0:34:13And then the back of your hands like that.
0:34:13 > 0:34:15And then rinse it all off, OK?
0:34:15 > 0:34:18So it's actually quite hard work.
0:34:18 > 0:34:21Bacteria are the one thing
0:34:21 > 0:34:25that we didn't have to put inside the box because they're already there.
0:34:25 > 0:34:27They're everywhere -
0:34:27 > 0:34:34tiny living things, or micro-organisms, that you can't see without a microscope.
0:34:34 > 0:34:38In the Rot Box, we have an incredible microscope
0:34:38 > 0:34:42that magnifies the bacteria a breathtaking 7,000 times.
0:34:42 > 0:34:46This allows us to have a much more detailed look.
0:34:46 > 0:34:49With enough food and water,
0:34:49 > 0:34:53the numbers of bacteria can increase alarmingly fast.
0:34:53 > 0:34:57They increase by dividing into two every 30 minutes,
0:34:57 > 0:35:00so after just 24 hours,
0:35:00 > 0:35:07one bacterium becomes just over 281 billion bacteria.
0:35:07 > 0:35:13They make up the largest number of living organisms on the planet.
0:35:13 > 0:35:19There are trillions and trillions and trillions of micro-organisms around the earth.
0:35:19 > 0:35:23But they're not all harmful, some of them help us.
0:35:23 > 0:35:29Importantly, bacteria live in our gut, helping us to digest our food.
0:35:32 > 0:35:35Now there are bacteria all over us obviously,
0:35:35 > 0:35:37but there's also lots of bacteria inside us.
0:35:37 > 0:35:44- Where do you think you could find lots of bacteria?- In your stomach. - Yeah, lots of bacteria.
0:35:44 > 0:35:46- Up your nose. - Yes, lots of bacteria there.
0:35:46 > 0:35:50- In your ears.- In your ears. Yes. Anywhere else?
0:35:50 > 0:35:52- In your mouth. - Particularly in your mouth,
0:35:52 > 0:35:56so lots of bacteria in there, some are good, some are bad.
0:35:56 > 0:36:01What I want to show you is how important it is to brush your teeth.
0:36:01 > 0:36:05I'm sending Iona and Mram off to brush their teeth so I can demonstrate
0:36:05 > 0:36:09how important it is to do it properly.
0:36:12 > 0:36:14- Have you brushed them properly?- Yes. - Yes.
0:36:14 > 0:36:18Well, I've got here little special tablets called disclosing tablets
0:36:18 > 0:36:21and you can have one each, right?
0:36:21 > 0:36:26It will show if you've really brushed your teeth properly,
0:36:26 > 0:36:28so what I want you do to is...
0:36:28 > 0:36:30in your mouth, roll it around your tongue
0:36:30 > 0:36:33and get all the liquid over your teeth and gums,
0:36:33 > 0:36:34do not swallow it,
0:36:34 > 0:36:36and then, once you've done that, go to the kitchen
0:36:36 > 0:36:40and spit it out and rinse your mouth out with fresh water
0:36:40 > 0:36:41and then come back.
0:36:42 > 0:36:43CHILDREN GIGGLE
0:36:45 > 0:36:46Now what this does is,
0:36:46 > 0:36:49the red dye sticks to the plaque.
0:36:49 > 0:36:52'Plaque is a sticky film containing bacteria
0:36:52 > 0:36:54'that can build up on your teeth.
0:36:54 > 0:36:57'The bacteria love to feed on sugar and when they feed,
0:36:57 > 0:37:00'they make acid which can rot your teeth.'
0:37:00 > 0:37:03It's very important to brush all that plaque off,
0:37:03 > 0:37:05that plaque bacteria off,
0:37:05 > 0:37:08and the red tablets show where the plaque is.
0:37:08 > 0:37:12Now you've brushed your teeth properly. Let's just see.
0:37:12 > 0:37:16You've got a little bit of plaque just on the bottom of that one.
0:37:17 > 0:37:21Yes, that's not too bad at all.
0:37:21 > 0:37:22Let me see.
0:37:23 > 0:37:25Open up.
0:37:25 > 0:37:28Now there's some plaque on the edge of that tooth there,
0:37:28 > 0:37:30some plaque along the edge of that side.
0:37:32 > 0:37:35Now the ones who haven't brushed their teeth, right? Oh!
0:37:35 > 0:37:37Oh-h!
0:37:37 > 0:37:39Let's see yours.
0:37:39 > 0:37:40Go, "Nnnnyah!"
0:37:42 > 0:37:47Yeah. Ruaridh, open up. Oh!
0:37:47 > 0:37:49I think you just had it on your tongue.
0:37:49 > 0:37:51You didn't roll it around your teeth.
0:37:51 > 0:37:57OK, that's quite clear to me that the two who've brushed their teeth
0:37:57 > 0:38:01have done quite a good job and you've removed most of the plaque.
0:38:01 > 0:38:03I'm impressed with you two.
0:38:08 > 0:38:12Bacteria are micro-organisms, tiny single-celled creatures
0:38:12 > 0:38:15that can't be seen without a microscope.
0:38:17 > 0:38:19They're absolutely everywhere
0:38:19 > 0:38:22and can multiply in numbers incredibly quickly.
0:38:22 > 0:38:28As a result, there are trillions and trillions and trillions of them on earth.
0:38:28 > 0:38:33Not all bacteria are harmful, some can be helpful too.
0:38:33 > 0:38:35They're very easily spread,
0:38:35 > 0:38:38so it's important to wash hands and brush teeth thoroughly.
0:38:38 > 0:38:42This will help to stop the spread of harmful bacteria
0:38:42 > 0:38:44or germs.
0:38:55 > 0:38:58Inside this large glass box,
0:38:58 > 0:39:01something extraordinary is happening.
0:39:01 > 0:39:08Food is being left to rot for eight weeks in our own unique laboratory.
0:39:11 > 0:39:12This is an investigation
0:39:12 > 0:39:18into nature's biggest and best recycler - decay.
0:39:18 > 0:39:23And it's being done on a scale that has never been tried before.
0:39:23 > 0:39:26I'm Dr George McGavin.
0:39:26 > 0:39:30I'm a biologist with a particular passion for insects.
0:39:30 > 0:39:34The Rot Box detectives, Iona, Rosie,
0:39:34 > 0:39:38Ruaridh, Mram and Jamie
0:39:38 > 0:39:43are going to help me investigate the amazing world of rot and decay.
0:39:47 > 0:39:49'There's mould...'
0:39:49 > 0:39:53The mould has just covered that entire box.
0:39:53 > 0:39:54'..bacteria...'
0:39:54 > 0:39:57- Where you can see those glowing bits...- Yeah.
0:39:57 > 0:39:59..that's bacteria.
0:39:59 > 0:40:00'..and flies.'
0:40:01 > 0:40:03It's pretty unpleasant, I've got to say.
0:40:07 > 0:40:10'It has taken eight months to build this giant Rot Box
0:40:10 > 0:40:14'and now conditions are perfect inside.
0:40:15 > 0:40:18'It's warm, there's water, air and plenty of food -
0:40:18 > 0:40:24'all the things decay loves to feast and grow on.
0:40:24 > 0:40:28'In the real world, female flies find the stench of rot irresistible
0:40:28 > 0:40:31'and will be attracted to it instantly,
0:40:31 > 0:40:35'as they find it the ideal place to lay their eggs,
0:40:35 > 0:40:39'but because our Rot Box is sealed, no smell is escaping,
0:40:39 > 0:40:42'so we need to put the flies into the box.'
0:40:42 > 0:40:44And there they go.
0:40:44 > 0:40:46Well, that's it. We're up and running
0:40:46 > 0:40:50and it's time to leave all this to the agents of decay.
0:40:55 > 0:40:57Back at Rot Box Detective HQ,
0:40:57 > 0:41:01we wanted to investigate flies in more detail.
0:41:01 > 0:41:04An adult fly can live up to five days,
0:41:04 > 0:41:09but in such a short life, this tiny creature is incredibly busy.
0:41:09 > 0:41:13This is a fly actually laying an egg. Now look at that.
0:41:13 > 0:41:16See? The female's got this long bit at the back of the abdomen
0:41:16 > 0:41:17through which the eggs pass,
0:41:17 > 0:41:21so she's actually laying eggs there on some meat.
0:41:21 > 0:41:23ALL: Wow!
0:41:23 > 0:41:27- Oh, that's a fly!- Oh, right!
0:41:27 > 0:41:29Now if we go to the maggot,
0:41:29 > 0:41:32when those eggs hatch and the little fly larvae,
0:41:32 > 0:41:34which are called maggots, hatch out,
0:41:34 > 0:41:36they've got little sharp hooks at the head end
0:41:36 > 0:41:39with which they tear the meat. Look at that.
0:41:39 > 0:41:41- Look. See?- That's horrible.
0:41:41 > 0:41:44And they just rip through the meat.
0:41:44 > 0:41:48Now the great thing about fly maggots is that they can breathe through special holes
0:41:48 > 0:41:51at their rear end called spiracles,
0:41:51 > 0:41:54so we breathe through our mouths, fly larvae haven't got that -
0:41:54 > 0:41:57they breathe through a system of tubes,
0:41:57 > 0:41:59so it can feed and breathe at the same time.
0:41:59 > 0:42:03And the last film is a fly after it's fully-grown,
0:42:03 > 0:42:05after the maggot's eaten all it can eat,
0:42:05 > 0:42:09it then becomes a pupae and it stays in there
0:42:09 > 0:42:12and it emerges as an adult fly and here is a film.
0:42:12 > 0:42:16Look at this. Wow! here is a fly actually emerging,
0:42:16 > 0:42:19and after it's pushed itself out, it dries one wing,
0:42:19 > 0:42:22and then it dries the other wing
0:42:22 > 0:42:23and then it flies off.
0:42:23 > 0:42:25Cool!
0:42:25 > 0:42:27Oh, look, now it's flying.
0:42:27 > 0:42:29Fantastic.
0:42:29 > 0:42:30There you go.
0:42:34 > 0:42:36We're making flytraps
0:42:36 > 0:42:38to see how many flies will smell our rotting fish,
0:42:38 > 0:42:42so that we can have a closer look at them in action.
0:42:51 > 0:42:57That's the trap made. What we have to do now to attract the flies is to put in the bait.
0:42:57 > 0:42:59Now, do you want a head or a tail?
0:42:59 > 0:43:01- A head.- Head. All right. Hold that.
0:43:01 > 0:43:05We should have one head left. Oh, there it is.
0:43:05 > 0:43:06- ALL: Eugh!- Eugh!
0:43:06 > 0:43:09Lovely fishy bait. Smelly, smelly. And then you put that in.
0:43:09 > 0:43:12Stick it in there. So there we are.
0:43:12 > 0:43:16Now, how do you think the trap works?
0:43:16 > 0:43:20The fly goes in that hole and then it gets stuck and then it can't fly out.
0:43:20 > 0:43:25- Yeah, it's like a creel or a lobster pot.- Can't it go out there?
0:43:25 > 0:43:29Some flies could fly out again, but flies are not terribly bright,
0:43:29 > 0:43:32and after they're in there, they tend to fly up,
0:43:32 > 0:43:36so they don't find the hole very easily,
0:43:36 > 0:43:39so although some of them will escape, not many of them escape.
0:43:39 > 0:43:42And there is your completed flytrap.
0:43:42 > 0:43:46- Awesome.- Now where would be the best place to hang them up?
0:43:46 > 0:43:50A bright place, somewhere really warm, so it attracts more flies
0:43:50 > 0:43:53- and the fish gets more rotten. - Absolutely.
0:43:53 > 0:43:57I'll bet you anything, within 30 seconds, there'll be flies in there.
0:43:57 > 0:43:59Oh, look, there's a fly in it already.
0:43:59 > 0:44:01Oh, see how efficient it is.
0:44:01 > 0:44:04Right, let's go.
0:44:07 > 0:44:11Now why do you think the adult flies are attracted to the dead fish?
0:44:11 > 0:44:16Because they want to leave an egg there?
0:44:16 > 0:44:18Absolutely. That's where they lay their eggs.
0:44:18 > 0:44:20Now adult flies don't live very long -
0:44:20 > 0:44:23they only live about five or six days,
0:44:23 > 0:44:24so when they're adult,
0:44:24 > 0:44:27the only job they have is to mate and to lay their eggs.
0:44:27 > 0:44:31I'm going to hang my trap up on this bolt over here,
0:44:31 > 0:44:34- and then we'll hang yours up on those trees, OK?- Mm-hm.
0:44:45 > 0:44:47'A few hours later,
0:44:47 > 0:44:50'and we're back at the traps to see if they're a success.'
0:44:50 > 0:44:53Right, let's see who's caught the most flies.
0:44:53 > 0:44:55- Whose trap is this one? - Me and Rosie.
0:44:55 > 0:44:59Right, well, you've got four flies on the inside,
0:44:59 > 0:45:03quite a few on the outside and you've got lots of eggs on the head,
0:45:03 > 0:45:04so that's really good.
0:45:04 > 0:45:06Look, we nearly got one!
0:45:06 > 0:45:09Let me see. Oh, you have got small ones on the outside.
0:45:09 > 0:45:12You've got one fly at the back there
0:45:12 > 0:45:14and no eggs.
0:45:14 > 0:45:16Mmm?
0:45:17 > 0:45:19And now, my trap...
0:45:20 > 0:45:22..ooh, look at that.
0:45:22 > 0:45:26- ALL: Oh-h!- There's at least one, two, three, four, five, six, seven flies in there -
0:45:26 > 0:45:29three species and lots of eggs. Look at that.
0:45:29 > 0:45:32You can see all the eggs over the mouth
0:45:32 > 0:45:36and in the mouth and on the head end, see? It could all change,
0:45:36 > 0:45:39- because there might be more flies in your traps tomorrow.- Yeah.
0:45:43 > 0:45:49After five weeks, the Rot Box has begun to look like a giant flytrap.
0:45:49 > 0:45:52There are now up to 10,000 flies trapped inside.
0:45:55 > 0:45:59Outside in the real world, these flies would have escaped
0:45:59 > 0:46:02out of a open window, but because the box is sealed,
0:46:02 > 0:46:07they've got nowhere to go and food is running out fast.
0:46:08 > 0:46:13I'm worried this huge number of flies will upset the balance of life in the box,
0:46:13 > 0:46:17so I've decided to go in and take control.
0:46:23 > 0:46:27Well, there are just now simply too many flies in here.
0:46:27 > 0:46:29It's becoming quite unpleasant,
0:46:29 > 0:46:30and it's causing a problem,
0:46:30 > 0:46:33because of the flyspeck, that's their excrement,
0:46:33 > 0:46:36which they leave on the surfaces inside the glass everywhere,
0:46:36 > 0:46:40so it's time I tried to reduce them a little bit...
0:46:41 > 0:46:43..manually.
0:46:43 > 0:46:47The trouble is, they're flying quite low
0:46:47 > 0:46:51and they're sitting on surfaces - it's actually very hard to get them.
0:46:57 > 0:46:59It's no wonder flies are so hard to capture.
0:46:59 > 0:47:02Their compound eyes give them all-round vision,
0:47:02 > 0:47:07so they can respond to movement in a fraction of a second.
0:47:09 > 0:47:11I'm never going to win this fly hunt.
0:47:16 > 0:47:19'The team and I are taking the fly hunt outside.'
0:47:19 > 0:47:22Right, well, we've been quite lucky with the rain.
0:47:22 > 0:47:23Yep.
0:47:24 > 0:47:27Oh, look at this. Look what I've found.
0:47:27 > 0:47:28Look.
0:47:30 > 0:47:34- Oh, wow!- Look at that.- Aw-w!
0:47:34 > 0:47:36Who knows what that is?
0:47:36 > 0:47:38- A pheasant.- Yeah, it's a female pheasant
0:47:38 > 0:47:40and I think it's probably been hit by a car, actually.
0:47:40 > 0:47:44In the real world, everything dies at some point,
0:47:44 > 0:47:49and when they do, bacteria start to act on them, breaking it down.
0:47:49 > 0:47:52They produce smells, bad odours which attract organisms,
0:47:52 > 0:47:55and if you remember back to your flytraps,
0:47:55 > 0:47:58the flies were attracted to the decaying fish pretty quickly,
0:47:58 > 0:48:00and the same thing will happen here.
0:48:00 > 0:48:04Now what would happen if we didn't have flies laying their eggs in it,
0:48:04 > 0:48:07and maggots eating it and other animals taking it away?
0:48:07 > 0:48:10- What would happen?- There'd be, like, loads of dead animals everywhere
0:48:10 > 0:48:12- and it would smell.- Exactly.
0:48:12 > 0:48:16Flies and other things that recycle dead animals
0:48:16 > 0:48:19really perform a fantastic job for us.
0:48:19 > 0:48:23Flies, particularly, are one of the most important recycling animals.
0:48:23 > 0:48:24Right, let's go.
0:48:32 > 0:48:35Back at the Rot Box, the cycle of life continues.
0:48:36 > 0:48:39Female flies are attracted to the rotting food,
0:48:39 > 0:48:42laying up to 300 eggs at a time.
0:48:43 > 0:48:46The eggs hatch into larvae called maggots.
0:48:46 > 0:48:50Maggots are amazing feeders. They use sharp hooks to eat
0:48:50 > 0:48:55and breathe through air holes called spiracles in their rear end.
0:48:55 > 0:48:57The maggots then become pupae
0:48:57 > 0:49:02from which young flies emerge and the whole cycle will begin again.
0:49:02 > 0:49:05So even though flies spread bacteria and mould
0:49:05 > 0:49:06by landing on fresh food,
0:49:06 > 0:49:10they have a very important job as recyclers.
0:49:17 > 0:49:20Inside this large glass box
0:49:20 > 0:49:23something extraordinary is happening.
0:49:23 > 0:49:30Food is being left to rot for eight weeks in our own unique laboratory.
0:49:33 > 0:49:38This is an investigation into nature's biggest and best recycler...
0:49:39 > 0:49:40..decay,
0:49:40 > 0:49:42and it's being done on a scale
0:49:42 > 0:49:47that has never been tried before.
0:49:47 > 0:49:48I'm Dr George McGavin.
0:49:48 > 0:49:52I'm a biologist with a particular passion for insects.
0:49:52 > 0:49:56The Rot Box detectives, Iona, Rosie,
0:49:56 > 0:50:00Ruaridh, Mram and Jamie
0:50:00 > 0:50:06are going to help me investigate the amazing world of rot and decay.
0:50:08 > 0:50:10'There's mound...'
0:50:10 > 0:50:14The melon's just incredible. It's really been hammered. Look at that.
0:50:14 > 0:50:15'..flies...'
0:50:15 > 0:50:19The number of flies has absolutely skyrocketed.
0:50:19 > 0:50:20'..and bacteria.'
0:50:28 > 0:50:31As well as food, there's a compost heap in the Rot Box,
0:50:31 > 0:50:34which includes vegetable waste and leaves.
0:50:36 > 0:50:41This is a great place to see decomposition in action.
0:50:41 > 0:50:44We've been adding green material to the top,
0:50:44 > 0:50:47but if we clear the top layers down, what's been happening in here
0:50:47 > 0:50:52is lots and lots of woodlice, worms beetles have been working away
0:50:52 > 0:50:55at the green material, breaking it down,
0:50:55 > 0:50:57decomposing it into smaller material,
0:50:57 > 0:50:59smaller particles,
0:50:59 > 0:51:01and that is then available for use
0:51:01 > 0:51:05by the billions of bacteria and fungi which are also in here.
0:51:05 > 0:51:10We'll be back to have a much more detailed look at these later on.
0:51:15 > 0:51:17Back at Rot Box Detective HQ,
0:51:17 > 0:51:20we are collecting leaves for our compost bin.
0:51:20 > 0:51:25It's the best place to see natural recycling at work.
0:51:29 > 0:51:34Right, let's come over to the compost bin.
0:51:34 > 0:51:35Let me take that.
0:51:35 > 0:51:40- Now do any of you do recycling? - Yeah, I do.
0:51:40 > 0:51:42Glass, paper and cardboard.
0:51:42 > 0:51:45- OK.- We recycle the garbage in our garden.- Right.
0:51:45 > 0:51:50- Oh, you do? So you've got a brown bin, have you?- Yeah.
0:51:50 > 0:51:55I've got a brown bin so I put, like, hedge cuttings and grass cuttings in it.
0:51:55 > 0:51:58- So all the waste from the garden ends up in here?- Yeah.- Yeah.
0:51:58 > 0:52:01That's what we're going to with the leaves we've raked up,
0:52:01 > 0:52:06but before we empty it in, put your hand in there, tell me what you feel.
0:52:06 > 0:52:08- Leaves.- Nothing.- Oh, it's warm.
0:52:08 > 0:52:09It's warm!
0:52:09 > 0:52:11- Oh, yeah.- Wow!
0:52:11 > 0:52:14Well, that's the bacteria breaking the stuff down.
0:52:14 > 0:52:18- Right, empty the leaves in.- Will there be enough room?- Oh, yeah.
0:52:18 > 0:52:23- Oh, yeah.- There we are.- Sorry. - Right.
0:52:23 > 0:52:24Who knows where this goes?
0:52:24 > 0:52:28Once you've filled up your brown bin, where does it go?
0:52:28 > 0:52:31- Bin lorry.- Ah, well, I'm going to show you.
0:52:47 > 0:52:52The leaves that we collected in the garden, we raked them up into the brown bin.
0:52:52 > 0:52:54The brown bin gets picked up by the truck,
0:52:54 > 0:52:58and the trucks all come here and there's one arriving now.
0:52:58 > 0:53:01They open the back, all the green material gets pushed out,
0:53:01 > 0:53:05and then a scoop comes and takes it to a shredder.
0:53:05 > 0:53:07That's where the whole process begins.
0:53:07 > 0:53:12It falls through these two huge rotating bars.
0:53:12 > 0:53:14It grinds it all up
0:53:14 > 0:53:16and it spits it out the bottom onto a bed
0:53:16 > 0:53:19and then it gets carried out there into a pile
0:53:19 > 0:53:21and the reason they do that is to break up
0:53:21 > 0:53:24all that material into smaller bits,
0:53:24 > 0:53:27so that it has a larger surface area,
0:53:27 > 0:53:28so the bacteria can get to work on it.
0:53:41 > 0:53:44Right, now, this... is where it all comes.
0:53:44 > 0:53:47So, once it's been through the shredder,
0:53:47 > 0:53:49it gets piled up in these long rows.
0:53:49 > 0:53:52Now, the reason they don't pile it in one great pile
0:53:52 > 0:53:56is if they had it in one huge pile, it would go all slimy,
0:53:56 > 0:53:57there'd be no oxygen in the middle.
0:53:57 > 0:53:59It would go all horrible.
0:53:59 > 0:54:02So they have it in these rows so they get lots of air in there
0:54:02 > 0:54:04and the air helps the bacteria and the decomposition.
0:54:04 > 0:54:09And what happens next is they put this through a screen or a sieve,
0:54:09 > 0:54:13it's like a giant sieve, and they take out all the big bits.
0:54:13 > 0:54:16So all you're left with is fine compost.
0:54:16 > 0:54:19- How hot do you think it is in there? - 20 degrees?- No.
0:54:19 > 0:54:22- 40?- No. Hotter than that.
0:54:22 > 0:54:24- 50 degrees? - Hotter than that.
0:54:24 > 0:54:29- 85 degrees.- That's a pretty good estimate. Let's see how hot it is.
0:54:29 > 0:54:33'I'm using a thermal probe to measure the heat inside the pile.'
0:54:34 > 0:54:36Let's see exactly how hot it is.
0:54:42 > 0:54:4547, 49...50...
0:54:46 > 0:54:48Going up!
0:54:49 > 0:54:51- Will it make 60?- Yes, it will.
0:54:51 > 0:54:55- It will, it will!- 59.9...
0:54:55 > 0:54:5660!
0:54:56 > 0:54:5960 and rising. Now, the reason it gets really hot in here
0:54:59 > 0:55:02is because there's billions of bacteria in here,
0:55:02 > 0:55:04breaking all the material down
0:55:04 > 0:55:08and as they break it down, they produce large amounts of heat.
0:55:08 > 0:55:09What's the highest?
0:55:09 > 0:55:13Some of these piles have even had fires in them
0:55:13 > 0:55:15cos it's just so hot. That's the power of bacteria.
0:55:19 > 0:55:21Now, once they've taken out all the big bits,
0:55:21 > 0:55:23all the big bits of wood and roots and stuff,
0:55:23 > 0:55:25the end result of all that recycling
0:55:25 > 0:55:28is this beautiful, beautiful compost.
0:55:28 > 0:55:30And that goes straight on your garden.
0:55:30 > 0:55:34Now, we've speeded it up by having it broken down into smaller bits,
0:55:34 > 0:55:38but recycling is happening all the time, all around us.
0:55:42 > 0:55:45Back in the giant Rot Box, we can take a much closer look
0:55:45 > 0:55:48at how recycling is happening in the compost heap.
0:55:54 > 0:55:57As all gardeners know, compost turns dead plants
0:55:57 > 0:56:01into a form of nutrient that new plants can use.
0:56:04 > 0:56:06On the surface, animals like snails, slugs
0:56:06 > 0:56:10and worms begin the process by eating the remains of plants,
0:56:10 > 0:56:13helping to break them into smaller pieces.
0:56:16 > 0:56:18Other small animals, like these mites,
0:56:18 > 0:56:22feed on the waste products these creatures leave behind.
0:56:24 > 0:56:27This process continues down through the compost,
0:56:27 > 0:56:30with ever-smaller organisms reducing the plant waste
0:56:30 > 0:56:35to ever-smaller pieces, until tiny micro-fauna
0:56:35 > 0:56:39and bacteria are able to break down the very cells of the plants.
0:56:41 > 0:56:46A teaspoon of soil contains four billion micro-organisms.
0:56:46 > 0:56:49They finally release the goodness back into the soil
0:56:49 > 0:56:51so that new organic life can grow.
0:56:57 > 0:57:02Composting is happening all around us in the natural world.
0:57:02 > 0:57:06I'm taking the Rot Box Detectives out to see if we can find some.
0:57:06 > 0:57:12Now, over here...is what I like to see. A bit of decaying wood.
0:57:13 > 0:57:16Now, look at this, this is fantastic.
0:57:16 > 0:57:20Now, this is a brilliant habitat for all kinds of stuff.
0:57:20 > 0:57:22This was once a piece of a tree.
0:57:22 > 0:57:24Obviously, it's fallen off
0:57:24 > 0:57:27and the whole of the wood is being eaten away,
0:57:27 > 0:57:29transformed into just...
0:57:29 > 0:57:31Look at that. It's all breaking down.
0:57:33 > 0:57:37The thing I love about decaying wood is it has a wonderful smell.
0:57:41 > 0:57:43Absolutely gorgeous.
0:57:45 > 0:57:48The whole of the wood is being eaten away,
0:57:48 > 0:57:50transformed into just... Look at that.
0:57:50 > 0:57:53It's exactly the same process that we saw earlier.
0:57:53 > 0:57:55It's recycling on a grand scale.
0:58:01 > 0:58:05Composting is nature's wonderful way of recycling.
0:58:05 > 0:58:09Plant and vegetable matter are gradually broken down.
0:58:10 > 0:58:13First, by larger organisms like snails, slugs, worms
0:58:13 > 0:58:19and woodlice, then by ever-smaller micro-organisms and bacteria.
0:58:20 > 0:58:24This process can be speeded up by breaking down the organic matter
0:58:24 > 0:58:28into small pieces, using machines.
0:58:28 > 0:58:30The end result is beautiful compost,
0:58:30 > 0:58:34full of goodness, ready to feed more plants
0:58:34 > 0:58:38so that the whole process of life and growth can begin again.
0:58:58 > 0:59:01Subtitles by Red Bee Media Ltd
0:59:01 > 0:59:04E-mail subtitling@bbc.co.uk