Getting ordinary plastic bags to rot away like banana peels would be an environmental dream come true.
After all, we produce 500 billion a year worldwide and they take up to 1,000 years to decompose. They take up space in landfills, litter our streets and parks, pollute the oceans and kill the animals that eat them.
Now a Waterloo teenager has found a way to make plastic bags degrade faster -- in three months, he figures.
Daniel Burd's project won the top prize at the Canada-Wide Science Fair in Ottawa. He came back with a long list of awards, including a $10,000 prize, a $20,000 scholarship, and recognition that he has found a practical way to help the environment.
Daniel, a 16-year-old Grade 11 student at Waterloo Collegiate Institute, got the idea for his project from everyday life.
"Almost every week I have to do chores and when I open the closet door, I have this avalanche of plastic bags falling on top of me," he said. "One day, I got tired of it and I wanted to know what other people are doing with these plastic bags."
The answer: not much. So he decided to do something himself.
He knew plastic does eventually degrade, and figured microorganisms must be behind it. His goal was to isolate the microorganisms that can break down plastic -- not an easy task because they don't exist in high numbers in nature.
First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.
After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.
Six weeks later, he weighed the strips of plastic. The control strips were the same. But the ones that had been in the live bacterial culture weighed an average of 17 per cent less.
That wasn't good enough for Burd. To identify the bacteria in his culture, he let them grow on agar plates and found he had four types of microbes. He tested those on more plastic strips and found only the second was capable of significant plastic degradation.
Next, Burd tried mixing his most effective strain with the others. He found strains one and two together produced a 32 per cent weight loss in his plastic strips. His theory is strain one helps strain two reproduce.
Tests to identify the strains found strain two was Sphingomonas bacteria and the helper was Pseudomonas.
A researcher in Ireland has found Pseudomonas is capable of degrading polystyrene, but as far as Burd and his teacher Mark Menhennet know -- and they've looked -- Burd's research on polyethelene plastic bags is a first.
Next, Burd tested his strains' effectiveness at different temperatures, concentrations and with the addition of sodium acetate as a ready source of carbon to help bacteria grow.
At 37 degrees and optimal bacterial concentration, with a bit of sodium acetate thrown in, Burd achieved 43 per cent degradation within six weeks.
The plastic he fished out then was visibly clearer and more brittle, and Burd guesses after six more weeks, it would be gone. He hasn't tried that yet.
To see if his process would work on a larger scale, he tried it with five or six whole bags in a bucket with the bacterial culture. That worked too.
Industrial application should be easy, said Burd. "All you need is a fermenter . . . your growth medium, your microbes and your plastic bags."
The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide -- each microbe produces only 0.01 per cent of its own infinitesimal weight in carbon dioxide, said Burd.
"This is a huge, huge step forward . . . We're using nature to solve a man-made problem."
Burd would like to take his project further and see it be used. He plans to study science at university, but in the meantime he's busy with things such as student council, sports and music.
"Dan is definitely a talented student all around and is poised to be a leading scientist in our community," said Menhennet, who led the school's science fair team but says he only helped Burd with paperwork.
Sciguy
05-25-2008, 02:28 PM
This is not the good news dream that it is represented to be. The problem with scientific discoveries is that they are applied by elites with their own agendas for making money in all kinds of ways that most of us would not like. Look at gunpowder, the weapons of war, all the greenwashing that misrepresents high-consumption as "ecological", the biofuel boondoggle, all those other discoveries that turn into products for domination and control. Clearly this is one more such.
The production elites are clear. They want us to all keep on making plastic bags out of petroleum or some other inappropriate raw material, such as food, and having barrels full of them used at every market.
No matter what happens to the current design of plastic bags, we all need to keep in mind that they are SINGLE USE PRODUCTS and therefore abominations from an environmental standpoint. Having a way to destroy any single use product after one use is NEVER a boon, except to the people who want to make more and more of them. It makes no difference if the destruction is carried out by melting or burning or composting or bacterial chomping. These are still single use products.
It has become common to emphasize only the most visually obvious drawbacks of products and to ignore all the more subtle but perhaps more important drawbacks. Single use falls into the category of subtle. Plastic bags on trees and in the ocean are the obvious ones. The common response, even among otherwise environmentally sophisticated folks is the dominator one. "Kill the plastic bags!" "Destroy them!" "Call them waste (preferably hazardous waste) and declare license to eliminate them by any means possible". Making biofuels out of so-called "agricultural waste" is another such idea. No matter that this way of framing essential soil nutrients and soil amendments i.e. as waste, is only one viewpoint and not a very sophisticated one at that. Similarly, framing lightweight plastic bags as waste and "a problem" is not where we need to go.
What we do need to do is to recognize the legitimate function that these bags serve (to carry bought products and other things conveniently) and find other ways to serve that same function using other methods THAT INVOLVE NO DISCARD AT ALL. We need some kind of robust bag or carrier OR IT COULD BE A DIFFERENT WAY OF FRAMING THE PROBLEM OF MOVING PRODUCTS NOT INVOLVING BAGS SUCH AS STORE DELIVERIES, without using single use products. Remember, single use means the constant waste of precious resources. Let's make the non-discard replacement that can be used for at least a hundred years. There is talk about seven generations - isn't that about a hundred or a hundred and forty years?
The simple and obvious replacement is a robust and specially designed bag (probably not these low grade quick bags that are popping up at stores without any basic design). Remember though that the FIRST IDEA for a better way is not usually the BEST IDEA.
This kind of analysis is called ZERO WASTE redesign. We need to redesign all of our products and processes from a non-discard point of view. Designing in single use plus quick destruction is not an answer. We need to become sophisticated enough to reject resource destruction no matter what form it raises its ugly head in.
Getting ordinary plastic bags to rot away like banana peels would be an environmental dream come true.
This is not the dream that it is represented to be. The problem with scientific discoveries is that they are applied by elites with their own agendas for making money in all kinds of ways that most of us would not like. Look at gunpowder, the weapons of war, all the greenwashing that misrepresents high-consumption as "ecological", all those other discoveries that turn into products for domination and control. Clearly this is one more such.
The production elites are clear. They want us to all keep on making plastic bags out of petroleum or some other inappropriate raw material, such as food, and having barrels full of them used at every market.
No matter what happens to the current design of plastic bags, we all need to keep in mind that they are SINGLE USE PRODUCTS and therefore abominations from an environmental standpoint. Having a way to destroy any single use product after one use is NEVER a boon, except to the people who want to make more and more of them. It makes no difference if the destruction is carried out by melting or burning or composting or bacterial chomping. These are still single use products.
It has become common to emphasize only the most visually obvious drawbacks of products and to ignore all the more subtle but perhaps more important drawbacks. Single use falls into the category of subtle. Plastic bags on trees and in the ocean are the obvious ones. The common response, even among otherwise environmentally sophisticated folks is the dominator one. "Kill the plastic bags!" "Destroy them!" "Call them waste (preferably hazardous waste) and declare license to eliminate them by any means possible. Making biofuels out of so-called "agricultural waste" is another such idea. No matter that this way of framing essential soil nutrients and soil amendments i.e. as waste, is only one viewpoint and not a very sophisticated one at that. Similarly, framing lightweight plastic bags as waste and "a problem" is not where we need to go.
What we do neet to do is to recognize the legitimate function that these bags serve (to carry bought products and other things conveniently) and find other ways to serve that same function using other methods THAT INVOLVE NO DISCARD AT ALL. We need some kind of robust bag or carrier OR IT COULD BE A DIFFERENT WAY OF FRAMING THE PROBLEM OF MOVING PRODUCTS NOT INVOLVING BAGS SUCH AS STORE DELIVERIES, without using single use products. Remember, single use means the constant waste of precious resources. Let's make the non-discard replacement that can be used for at least a hundred years. There is talk about seven generations - isn't that about a hundred or a hundred and forty years?
This kind of analysis is called ZERO WASTE redesign. We need to redesign all of our products and processes from a non-discard point of view. Designing single use plus quick destruction is not an answer. We need to become sophisticated enough to reject resource destruction no matter what form it raises its ugly head in.
Sciguy
After all, we produce 500 billion a year worldwide and they take up to 1,000 years to decompose. They take up space in landfills, litter our streets and parks, pollute the oceans and kill the animals that eat them.
Now a Waterloo teenager has found a way to make plastic bags degrade faster -- in three months, he figures.
Daniel Burd's project won the top prize at the Canada-Wide Science Fair in Ottawa. He came back with a long list of awards, including a $10,000 prize, a $20,000 scholarship, and recognition that he has found a practical way to help the environment.
Daniel, a 16-year-old Grade 11 student at Waterloo Collegiate Institute, got the idea for his project from everyday life.
"Almost every week I have to do chores and when I open the closet door, I have this avalanche of plastic bags falling on top of me," he said. "One day, I got tired of it and I wanted to know what other people are doing with these plastic bags."
The answer: not much. So he decided to do something himself.
He knew plastic does eventually degrade, and figured microorganisms must be behind it. His goal was to isolate the microorganisms that can break down plastic -- not an easy task because they don't exist in high numbers in nature.
First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.
After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.
Six weeks later, he weighed the strips of plastic. The control strips were the same. But the ones that had been in the live bacterial culture weighed an average of 17 per cent less.
That wasn't good enough for Burd. To identify the bacteria in his culture, he let them grow on agar plates and found he had four types of microbes. He tested those on more plastic strips and found only the second was capable of significant plastic degradation.
Next, Burd tried mixing his most effective strain with the others. He found strains one and two together produced a 32 per cent weight loss in his plastic strips. His theory is strain one helps strain two reproduce.
Tests to identify the strains found strain two was Sphingomonas bacteria and the helper was Pseudomonas.
A researcher in Ireland has found Pseudomonas is capable of degrading polystyrene, but as far as Burd and his teacher Mark Menhennet know -- and they've looked -- Burd's research on polyethelene plastic bags is a first.
Next, Burd tested his strains' effectiveness at different temperatures, concentrations and with the addition of sodium acetate as a ready source of carbon to help bacteria grow.
At 37 degrees and optimal bacterial concentration, with a bit of sodium acetate thrown in, Burd achieved 43 per cent degradation within six weeks.
The plastic he fished out then was visibly clearer and more brittle, and Burd guesses after six more weeks, it would be gone. He hasn't tried that yet.
To see if his process would work on a larger scale, he tried it with five or six whole bags in a bucket with the bacterial culture. That worked too.
Industrial application should be easy, said Burd. "All you need is a fermenter . . . your growth medium, your microbes and your plastic bags."
The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide -- each microbe produces only 0.01 per cent of its own infinitesimal weight in carbon dioxide, said Burd.
"This is a huge, huge step forward . . . We're using nature to solve a man-made problem."
Burd would like to take his project further and see it be used. He plans to study science at university, but in the meantime he's busy with things such as student council, sports and music.
"Dan is definitely a talented student all around and is poised to be a leading scientist in our community," said Menhennet, who led the school's science fair team but says he only helped Burd with paperwork.
Lenny
05-25-2008, 06:50 PM
Dear Sci Guy, you scare me. They are only plastic bags. I sense a zeal (great) out of proportion to what the issue is. The youngster found a way to dissolve them so maybe he could get a hurray, instead of a gloom/doom, no? Yours is the approach that gives Progressives a tough time in marketing the ideas to the rest of US. I know you don't give a fig, and that is OK, but for those of us trying to get across, give it a rest. Besides, what you wrote is not bad science, but bad economics and politics. You mention gunpowder, etc. You might as well mention fire. Fire bad, eh? Now I realize you would want to go and have us all grow our own and discard, out of hand, our chemicals. That would doom about all of the peoples of Africa, quite a bit of South East Asia, as a matter of fact, probably about 80% of the planet's population. You scare me. You a vegetarian, too?
Hummingbear
05-26-2008, 12:52 AM
No matter what happens to the current design of plastic bags, we all need to keep in mind that they are SINGLE USE PRODUCTS and therefore abominations from an environmental standpoint. Having a way to destroy any single use product after one use is NEVER a boon, except to the people who want to make more and more of them.
I support zero-waste policies, and I agree that people should use alternative bags that are reused rather than discarded (as I generally do).
But meanwhile, in real life, we have a Texas-sized flotilla of plastic crap in the middle of the Pacific, killing huge areas of marine habitat. We desperately need a tool to return this crap to its organic components so it stops being destructive. But you say that finding a way to do this is not good news?
Sorry, I think you are missing the point. Gaining this technical tool is absolutely priceless. Manifesting the social conscience needed to use it properly, rather than in the service of continued abuse of resources, is even more important, but that's a totally separate process.
Hummingbear
Sciguy
05-26-2008, 01:21 AM
Hummingbear:
Destroying EXISTING flotillas of plastic bags would be desirable. But the people who are in charge are going to pooh-pooh that use, while they try to apply destruction technologies to their single use methods in markets immediately. We have seen the cynical way they have cast about to use recycling (quite inappropriate) or biodegradable bags to try to keep the river of plastic bags flowing into garbage.
Besides which, that flotilla is in salt water and there is no indication in the article that any salt water bacteria were even considered.
My letter was about SINGLE USE being joined to DESTRUCTION. It has implications for every kind of single use product in our ecomomy. Plastic bags were not the main focus. I was responding to the concept that a destruction technique is the dream gift we are waiting for. I disagree. Destruction of resources is a nightmare. We have quite enough of that thank you in all of the garbage dumps. Torrents of planned obsolescence single use products is far more important and long term than the flotillas of plastic in the ocean. The sun will slowly solve the ocean problem, but only if we stop adding to the mass. Sympathy for fish is wonderful but it is being cynically used to generate sympathy for destruction, ostensibly to solve problems that no one with power cares about. After all, how many tears is Exxon crying over the devastation of their Exxon Valdez spill, even eleven years later? Or Dow over their Bhopal explosion? They can live with dying fish or people but they can't live without their plastic markets.
You must have noticed how the oil companies and the pharmaceutical companies (and all others) constantly pull a switcheroo when they are arguing for subsidies and tax relief and justifying their profits. The profits for officers and shareholders are never mentioned. Instead, they only talk about jobs - as though social good was the only concern on their mind. In the same way, environmental problems are used as a smokescreen to get the public behind dreadful, anti-environmental plans that, just coincidentally, are going to make lots of money for the producers. Planned obsolescence (single use) is sold this way. Plastic bags are "more energy efficient". Plastic water bottles "save on transportation costs". Recycling "creates jobs". Nuclear plants create "years of construction jobs". We need to look behind the easy justifications for feel-good solutions and become aware of the core economics that is being pushed.
Sciguy
I support zero-waste policies, and I agree that people should use alternative bags that are reused rather than discarded (as I generally do).
But meanwhile, in real life, we have a Texas-sized flotilla of plastic crap in the middle of the Pacific, killing huge areas of marine habitat. We desperately need a tool to return this crap to its organic components so it stops being destructive. But you say that finding a way to do this is not good news?
Sorry, I think you are missing the point. Gaining this technical tool is absolutely priceless. Manifesting the social conscience needed to use it properly, rather than in the service of continued abuse of resources, is even more important, but that's a totally separate process.
Hummingbear
Zeno Swijtink
05-26-2008, 09:31 PM
Dear Sci Guy, you scare me. They are only plastic bags. I sense a zeal (great) out of proportion to what the issue is. The youngster found a way to dissolve them so maybe he could get a hurray, instead of a gloom/doom, no? Yours is the approach that gives Progressives a tough time in marketing the ideas to the rest of US. I know you don't give a fig, and that is OK, but for those of us trying to get across, give it a rest. Besides, what you wrote is not bad science, but bad economics and politics. You mention gunpowder, etc. You might as well mention fire. Fire bad, eh? Now I realize you would want to go and have us all grow our own and discard, out of hand, our chemicals. That would doom about all of the peoples of Africa, quite a bit of South East Asia, as a matter of fact, probably about 80% of the planet's population. You scare me. You a vegetarian, too?
Following up on you, not contradicting you, but really raising a question for Paul Palmer:
My thinking is confused at this point, bear with me if you can. My thinking is: zero-waste is a tautology. Meaning, in nature nothing is wasted, eventually. Life forms will emerge, or have emerge already, that feast on what another life form has excreted. Sometimes they form symbiotic relations, as in the following story. This opens up evolutionary pathways for creatures with stomachs that can digest plastics.
****
US Studies Show Germs Help Species Evolve (https://www.planetark.com/dailynewsstory.cfm/newsid/48464/story.htm)
May 23, 2008
WASHINGTON - The germs that help cattle eat grass and gorillas gorge on leaves may have been the secret weapon that let mammals populate the planet, researchers reported on Thursday.
Two separate teams of researchers reported on the bacteria living in and on the bodies of humans and other animals, and found they are surprisingly well-adapted to their hosts -- so well that they may have helped different species evolve.
"We have evolved together with our bacteria," Dr. Julie Segre of the National Human Genome Research Institute said in a telephone interview.
Both teams looked at the DNA of the bacteria, as opposed to trying to painstakingly grow them in lab dishes. They said this method helped them find species missed by older techniques.
Not only have the microbes evolved with us, but perhaps animals that have made good use of bacteria have been able to evolve further, one team of US researchers said.
In another study, Segre's team found more than 130 different species living on the skin, many that no one knew were there before.
"I thought it was amazing that there were a million bacteria per square centimeter. The bacterial cells outnumber us," said Segre, whose study is published in the journal Genome Research.
Jeffrey Gordon of Washington University in St. Louis and colleagues looked at the droppings of 60 different species of mammals and found meat-eaters, plant-eaters and omnivores such as humans each have their own unique set of gut bacteria.
Writing in the journal Science, they said the ability of mammals to acquire new symbiotic bacteria in their digestive systems may have helped so many different species evolve.
"This could account for the spectacular success of mammals and herbivores in particular," they wrote.
DIGESTIVE AIDS
Animals, and especially mammals, make use of bacteria to help digest their food. Gordon's team found that herbivores had the most diverse species of bacteria in their faeces -- a not surprising finding given that the bugs are needed to break down the tough cellulose found in grasses and other plants.
Carnivores had the fewest number of different species and omnivores fell in the middle. Human poop bacteria looked much like that of other omnivores, they said.
Members of the same species living in the wild and in zoos had similar gut bacteria. And a strict vegetarian human had similar bacterial residents to the meat-eating people.
A team at The Institute for Genomic Research in Maryland found in 2006 found that the number of bacteria in the human gut outnumber the cells in our bodies, and proposed that many be classified as true symbionts with Homo sapiens.
Segre's team took samples from the insides of the elbows -- a place known to be prone to eczema, a flaking skin disorder. Psoriasis, another skin disease, is found on the outside of the elbow and she believes bacterial and fungal populations may play a role.
Learning how to manipulate bacteria may hold the secret to treating these diseases, Segre said. Bacteria that break down the sebaceous output of tiny skin glands help turn the waxy substance into natural moisturizer and learning more about how they do this could form the basis of an entire new beauty industry.
"I think we do really need to change the language about thinking about bacteria as pathogenic," Segre said. "We should appreciate bacteria as helping our health."
***
https://www.sciencemag.org/cgi/content/full/320/5879/1001
Science 23 May 2008:
Vol. 320. no. 5879, p. 1001
NEWS OF THE WEEK
MICROBIOLOGY:
Bacteria Are Picky About Their Homes on Human Skin
Elizabeth Pennisi
Julie Segre is touring the microbial landscape of our body's biggest organ, the skin. In anticipation of a $115 million, 5-year effort by the U.S. National Institutes of Health (NIH), she's traveling from head to toe, conducting a census of some of the trillions of bacteria that live within and upon human skin. Although their project is just getting off the ground, Segre, a geneticist at the National Human Genome Research Institute (NHGRI) in Bethesda, Maryland, and her colleagues have already uncovered a surprising diversity and distribution among skin bacteria. And a few oddities have emerged, too: Microbes known mostly from soils like healthy human skin, living in harmony with us; and the space between our toes is a bacterial desert compared to the nose and belly button.
Segre's work on what bacteria live where "is cool stuff," says Steven Salzberg, a bio-informaticist at the University of Maryland, College Park. "We need to increase our own and the public's awareness of the diversity and quantity of bacterial species on our own skin. The more people are aware, the more we can do to control infection."
Bacteria and other microbes that colonize our skin and other tissues outnumber the human body's cells 10 to 1, forming dynamic communities that influence our ability to develop, fight infection, and digest nutrients. "We're an amalgamation of the human and microbial genomes," says Segre. Recognizing this, NIH last year designated the Human Microbiome Project as one of its two Roadmap initiatives (Science, 2 June 2006, p. 1355). Researchers will sequence the genomes of about 600 bacteria identified as human inhabitants and get a handle on the 99% of bacteria that defy culturing but thrive in the skin, nose, gut, mouth, or vagina. "You have to understand what is the normal flora in the healthy skin to understand the impact of flora on disease," says Kevin Cooper, a dermatologist at Case Western Reserve University in Cleveland, Ohio.
As a first step, Segre, NHGRI postdoctoral fellow Elizabeth Grice, and their colleagues have studied five healthy volunteers, swabbing the insides of their right and left elbows. The site chosen isn't as unusual as it sounds; people with eczema often develop symptoms there. To survey the full thickness of skin, the researchers also used a scalpel to scrape off the top cel ls. And to reach even deeper, they took small "punches" of skin, a procedure akin to removing a mole.
From all the samples, Grice, Segre, and colleagues pulled out 5300 16S ribosomal RNA genes, which vary from microbe to microbe. After lumping together the most similar 16S genes, they came up with 113 kinds of bacteria and identified these dermal residents by matching the 16S genes to those of known bacteria. (Segre described the results at a recent meeting at Cold Spring Harbor Laboratory, and they are being published online 23 May in Genome Research.) "That's a lot of diversity, a lot of different organisms," says Martin Blaser, a microbiologist at New York University, who has done a similar survey of microbes living on the forearm, also finding a lot of diversity.
Yet just 10 bacteria accounted for more than 90% of the sequences. Almost 60% of the 16S genes came from Pseudomonas, Gram-negative bacteria that flourish in soil, water, and decomposing organic debris. The next most common one, accounting for 20%, was another Gram-negative soil and water bug, Janthinobacterium. Neither had been considered skin microbes before this census. Although there were some differences among the volunteers in the microbes present, their elbows did share a common core set of microbes, the group reports.
The three sampling methods yielded slightly different results, with "punches" revealing a surprising number of bacteria under the skin--1 million bacteria per square centimeter compared with 10,000 from the scrapes. "I would have thought under the skin there would be fewer," says Salzberg.
Segre and her team have also begun sampling 20 other skin sites, including behind the ear and the armpit, from the bodies of volunteers. Skin varies in acidity, temperature, moisture, oil accumulation, and "different environments select for different microbes," says Blaser. Bacteriawise, reports Segre, "no subsite is identical."
Some researchers suspect that shifts in the makeup of skin microbial communities activate the immune system to cause diseases such as eczema. "If you know what the [healthy] flora is, then one strategy is to recolonize the area with the right flora," says Cooper.
--
NOTICE: In accordance with Title 17 U.S.C., section 107, some material is provided without permission from the copyright owner, only for purposes of criticism, comment, scholarship and research under the "fair use" provisions of federal copyright laws. These materials may not be distributed further, except for "fair use," without permission of the copyright owner. For more information go to: https://www.law.cornell.edu/uscode/17/107.shtml
Lenny
05-27-2008, 06:08 AM
Whoa. So it turns out we are a walking smorgasbord for critters?
Zounds!
Thanks for bringing balance to a lopsided discussion.
And thanks for posting the below as well.
Following up on you, not contradicting you, but really raising a question for Paul Palmer:
My thinking is confused at this point, bear with me if you can. My thinking is: zero-waste is a tautology. Meaning, in nature nothing is wasted, eventually. Life forms will emerge, or have emerge already, that feast on what another life form has excreted. Sometimes they form symbiotic relations, as in the following story. This opens up evolutionary pathways for creatures with stomachs that can digest plastics.
****
US Studies Show Germs Help Species Evolve (https://www.planetark.com/dailynewsstory.cfm/newsid/48464/story.htm)
May 23, 2008
WASHINGTON - The germs that help cattle eat grass and gorillas gorge on leaves may have been the secret weapon that let mammals populate the planet, researchers reported on Thursday.
"We have evolved together with our bacteria," Dr. Julie Segre of the National Human Genome Research Institute said in a telephone interview.
"I thought it was amazing that there were a million bacteria per square centimeter. The bacterial cells outnumber us," said Segre, whose study is published in the journal Genome Research.
Jeffrey Gordon of Washington University in St. Louis and colleagues looked at the droppings of 60 different species of mammals and found meat-eaters, plant-eaters and omnivores such as humans each have their own unique set of gut bacteria.
Animals, and especially mammals, make use of bacteria to help digest their food. Gordon's team found that herbivores had the most diverse species of bacteria in their faeces -- a not surprising finding given that the bugs are needed to break down the tough cellulose found in grasses and other plants.
Carnivores had the fewest number of different species and omnivores fell in the middle. Human poop bacteria looked much like that of other omnivores, they said.
Members of the same species living in the wild and in zoos had similar gut bacteria. And a strict vegetarian human had similar bacterial residents to the meat-eating people.
A team at The Institute for Genomic Research in Maryland found in 2006 found that the number of bacteria in the human gut outnumber the cells in our bodies, and proposed that many be classified as true symbionts with Homo sapiens.
***
https://www.sciencemag.org/cgi/content/full/320/5879/1001
Science 23 May 2008:
And a few oddities have emerged, too: Microbes known mostly from soils like healthy human skin, living in harmony with us; and the space between our toes is a bacterial desert compared to the nose and belly button.
l (https://www.law.cornell.edu/uscode/17/107.shtml)