Scientists just discovered plastic-eating bacteria that can break down PET

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Bon appétit!

This article was written by Mark Lorch from the University of Hull, and was originally published by The Conversation.

We manufacture over 300 million tonnes of plastics each year for use in everything from packaging to clothing. Their resilience is great when you want a product to last. But once discarded, plastics linger in the environment, littering streets, fields and oceans alike. Every corner of our planet has been blighted by our addiction to plastic. But now we may have some help to clean up the mess in the form of bacteria that have been found slowly munching away on discarded bottles in the sludge of a recycling centre.

Plastics are polymers, long thin molecules made of repeating (monomer) building blocks. These are cross-linked to one another to build a durable, malleable mesh. Most plastics are made from carbon-based monomers, so in theory they are a good source of food for microorganisms.

But unlike natural polymers (such as cellulose in plants) plastics aren’t generally biodegradable. Bacteria and fungi co-evolved with natural materials, all the while coming up with new biochemical methods to harness the resources from dead matter.

But plastics have only been around for about 70 years. So microorganisms simply haven’t had much time to evolve the necessary biochemical tool kit to latch onto the plastic fibres, break them up into the constituent parts and then utilise the resulting chemicals as a source of energy and carbon that they need to grow.

Enzyme innovation

Now a team at Kyoto University has, by rummaging around in piles of waste, found a plastic munching microbe. After five years of searching through 250 samples, they isolated a bacteria that could live on poly(ethylene terephthalate) (PET), a common plastic used in bottles and clothing. They named the new species of bacteria Ideonella sakaiensis.

You may think this is the rerun of an old story, as plastic-eating microbes have already been touted as saviours of the planet. But there are several important differences here.

First, previous reports were of tricky-to-cultivate fungi, where in this case the microbe is easily grown. The researchers more or less left the PET in a warm jar with the bacterial culture and some other nutrients, and a few weeks later all the plastic was gone.

Bottle breakdown. Illustration: P. Huey. Reprinted with permission from U.T. Bornscheuer, Science 351:1154 (2016)

Second - and the real innovation - is that the team has identified the enzymes that Ideonella sakaiensis uses to breakdown the PET. All living things contain enzymes that they use to speed up necessary chemical reactions. Some enzymes help digest our food, dismantling it into useful building blocks. Without the necessary enzymes the body can’t access certain sources of food.

For example, people who are lactose intolerant don’t have the enzyme that breaks down the lactose sugar found in dairy produce. And no human can digest cellulose, while some microbes can. Ideonella sakaiensis seems to have evolved an efficient enzyme that the bacteria produces when it is in an environment that is rich in PET.

The Kyoto researchers identified the gene in the bacteria’s DNA that is responsible for the PET-digesting enzyme. They then were able to manufacture more of the enzyme and then demonstrate that PET could be broken down with the enzyme alone.

First real recycling

This opens a whole new approach to plastic recycling and decontamination. At present, most plastic bottles are not truly recycled. Instead they are melted and reformed into other hard plastic products. Packaging companies typically prefer freshly made 'virgin' plastics that are created from chemical starting materials that are usually derived from oil.

The PET-digesting enzymes offer a way to truly recycle plastic. They could be added to vats of waste, breaking all the bottles or other plastic items down into into easy-to-handle chemicals. These could then be used to make fresh plastics, producing a true recycling system.

Manufactured enzymes are already used to great effect in a wide range of everyday items. Biological washing powders contain enzymes that digest fatty stains. The enzymes known as rennet that are used to harden cheese once came from calfs’ intestines but are now manufactured using genetically engineered bacteria. Maybe we can now use a similar manufacturing method to clean up our mess.

Mark Lorch, Senior Lecturer in Biological Chemistry, Associate Dean for Engagement, University of Hull.

This article was originally published by The Conversation. Read the original article.

ORIGINAL: Science Alert

MARK LORCH, THE CONVERSATION

10 MAR 2016

Trend-setting chimp teaches friend to use a straw

ORIGINAL: New Scientist

By Sandrine Ceurstemont, editor, New Scientist TV

31 January 2013

If your friend has a more efficient way of getting food, it makes sense to copy them. Now an experiment is showing for the first time that chimps also come to the same conclusion.

Captured by Shinya Yamamoto from Kyoto University in Japan and colleagues, this video shows how a chimp improves its use of a straw after observing a more proficient companion. At first, it uses the tool almost like an eye-dropper, dipping it in a box to sop up juice. But after it watches its friend drink faster by sucking on the straw, it learns to adopt this new approach. According to the team, which studied nine chimps, once an ape switched to straw-sucking, it never went back to the less efficient dipping technique.

Although it's well known that chimps learn socially, it's the first time they've been shown to improve the way they use a tool, which is a comparatively sophisticated ability. It requires a chimp to differentiate between two techniques involving the same instrument to achieve an identical goal.

The experiment shows that these apes have the mental capacity to evolve their cultural learning. "The limitations might be due to ecological, social and motivational factors rather than cognitive abilities," write the researchers.

If you enjoyed this clip, see how chimps carry corpses to mourn their dead or watch a bonobo genius make stone tools.

Japan researchers say kidney tissue grown from stem cells (Update)

ORIGINAL: MedicalXpress

by Harumi Ozawa in Medical research

January 23, 2013 

A scientist is pictured on August 27, 2010 working on stem cells in a laboratory. Researchers in Japan said Wednesday they have succeeded in growing human kidney tissue from stem cells for the first time in a potential breakthrough for millions with damaged organs who are dependent on dialysis.

Researchers in Japan said Wednesday they have succeeded in growing human kidney tissue from stem cells for the first time, in a potential first step towards helping millions who depend on dialysis. 

Kidneys have a complex structure that is not easily repaired, but the latest findings put scientists on the road to fixing a diseased or distressed organ, they said.

More than 300,000 people in Japan alone rely on dialysis because their kidneys do not function properly. Researchers said the latest breakthrough may one day mean that kidney tissue generated from a patient's own body could markedly improve how a damaged organ works.

Kenji Osafune of Kyoto University said his team had managed to take stem cells—the "blank slates" capable of being programmed to become any kind of cell in the body—and nudge them specifically in the direction of kidney tissue.

"It was a very significant step," he told AFP.

Osafune said they had succeeded in generating intermediate mesoderm tissue from the stem cells, a middle point between the blank slate and the finished kidney tissue.

"There are about 200 types of cells in the human body, but this tissue grows into only three types of cells," namely adrenal cells, reproductive gland cells and kidney cells, he said, adding that as much as 90 percent of cultures in their research developed into viable mesoderm tissue.

This embryonic intermediary can be grown either in test tubes or in a living host into specific kidney cells.

Osafune stressed there are still many hurdles to overcome before applying his work to actual medical treatment. "It is not known yet if simply transplanting regenerated cells would really cure kidney ailment," he said.

He and his team created part of a urinary tubule, a small tube in the kidney that plays a role in the production of urine.

While the research is not aimed at growing an entire working kidney, he said the method his team had developed would help scientists learn more about intermediate mesoderm development and may provide a source of cells for regenerative therapy.

"I would say that we have arrived at the preliminary step on the road to the clinical level," he said.

Stem cell work has been controversial until relatively recently because embryos were the only source, and their harvesting led to the destruction of what some people consider a human life.

This research has used induced Pluripotent Stem (iPS) cells, a bio-technology where a fully-developed adult cell is effectively re-engineered to return it to its infant state.

Last year Shinya Yamanaka, director of the Centre for iPS Cell Research and Application of which Osafune is a part, was a co-recipient of the Nobel Prize for medicine for his pioneering work on the iPS cells.

Yamanaka and Britain's John Gurdon were jointly honoured for work on the key ingredient in the vision of regenerative medicine.

Work involving iPS cells is seen as a way scientists can generate materials either to experiment on, or to use within the body—perhaps as a means of repairing or even replacing damaged or diseased organs.

Osafune's achivement, while significant, brings researchers effectively to the foot of a mountain they must climb if they want to grow a working kidney, warned Takahashi Yokoo, lecturer at Jikei University School of Medicine in Tokyo.

"Yes, a tubule structure was generated, but an enormous amount of research is still necessary to create an orderly structure that produces urine," Yokoo, a kidney expert not involved with Osafune's study, told AFP.

"We must refrain from hyping optimism among patients because to do so is to ignore the most difficult part of the efforts to create kidneys." 

"We are hopeful about the latest achievement. This study puts us at the starting line for a big mission ahead."

Osafune's research is published in online science journal Nature Communications.

Journal reference: Nature Communications

(c) 2013 AFP