Plastics Will Be Toast, Thanks To Moonlighting Microbes

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Petroleum stakeholders have been seeking safe haven in plastics and other petrochemicals now that global demand for fossil fuel is crashing. However, science is about to crash the gate with new bio-based alternatives. In the latest development, researchers have discovered that certain microbes can moonlight as refineries. They can produce ethylene, a building block for all sorts of plastics as well as glues, coolants, and other products that currently rely on oil and gas.

biobased plastics renewable bioenergy crops
A new breakthrough in bio-based plastics aims a dagger at the heart of petrochemicals and fossil fuels, too (image via ORNL).

Bio-based Plastics From Tiny Little Bugs

The research is significant because it could hold the key to a sustainability twofer. In addition to demonstrating a bio-based alternative to fossil plastics, the research team also unlocked the mystery of how and why oxygen-deprived soils can damage crops.

Ethylene is necessary for plant growth in small quantities, but in higher levels it can be lethal. The new research shows that the problem occurs in oxygen-deprived (aka anaerobic) soil. That typically occurs when conditions are waterlogged, causing the bacteria to become starved for sulfur. Their metabolism goes into overdrive trying to scavenge it, and that results in an over-production of ethylene.

With the new knowledge in hand, researchers may be able to find ways to prevent crop damage and grow healthier crops even under oxygen-poor conditions.

Actually, make that a three-for. Everybody knows that bacteria can produce the powerful greenhouse gas methane, but they can do it in different ways. In recent years scientists have been discovering some of those previously unknown ways. The new research adds to the body of knowledge by unveiling yet another different pathway, which could lead to new strategies for reducing methane emissions from landfills and other bio-based sources.

What’s In A Name?

The new research comes from a team based at the Energy Department’s Oak Ridge National Laboratory and Ohio State University, where the scientists have been studying how photosynthetic bacteria fix carbon and metabolize nitrogen and sulfur. With the help of cutting edge analytical tools for characterizing microbial systems, they poked around until they settled on a bug called Rhodospirillum rubrum and several others in the same family.

You can get all the details from the study, “A nitrogenase-like enzyme system catalyzes methionine, ethylene, and methane biogenesis,” newly published in the journal Science.

For those of you on the go, that word “nitrogenase-like” hints at one of the most significant findings of the study. The researchers culled through thousands of protein samples to pinpoint the ones connected to sulfur pathway, and they were quite surprised to find that the key was a family of nitrogenase-like proteins. They were surprised because the name nitrogenase-like indicates that these proteins are connected to a different pathway, in which microbes convert atmospheric nitrogen to ammonia.

It seems that for quite a while now, researchers interested in the sulfur component have largely ignored that particular group because the name indicates it is not particularly relevant. Now that the confusion has been cleared up, there may be quite a few more studies rippling out.

That’s going to spell more bad news for fossil fuel stakeholders. The research is specifically focused on preventing damage to switchgrass and other biofuel crops, so there’s that.

Bio-based Plastics, Just In The Nick Of Time

The next step in the research is to scale up the labwork, so it will be quite a long time before ranks of hopped-up microbes are enlisted to spit out bio-based plastics for the commercial market.

They better act fast. Fossil stakeholders are eyeballing growth markets in Asia and elsewhere to keep the demand for oil and gas afloat.

On the other hand, one need not wait for the microbes. Other types of bio-based plastics have been on the market for many years, and it looks like the sector is primed for growth.

In newly released report on biodegradable plastics, analysts with the firm MarketStudyReport LLC are forecasting strong growth in that sector, which they attribute to “rising adoption of CSR (corporate social responsibility) practices among various enterprises and focus towards reducing the dependency on synthetic resources,” along with plastic bag bans and other government actions. Consumer awareness about global warming also comes into play.

On the downside, petroleum producers can take advantage of lower prices to counterbalance the interest in bio-based plastics. That cost advantage has been exacerbated by the economic fallout from the COVID-19 outbreak. The financial pressure has left manufacturers with less wiggle room to include more costly sources in their supply chain.

One Word: Starch

COVID or not, the new report is still looking at significant growth in bioplastics, and they are zeroing in on starch.

The product landscape of global biodegradable plastics market is split into PBS, PHA, PLA, starch blends and others. Estimates claim that starch blends segment is expected to hold the largest market share by the end of the forecast period,” they explain.

That’s partly because starch-based plastics do double duty, both as packaging and as as edible films.

They also point out that starch-based bioplastics are expanding beyond packaging and into other major areas. One leading example is agriculture, where starch-based plastics are beginning to gain a foot hold as an additive for fertilizers.

Dark Clouds Ahead For Conventional Plastics

There is much more to the report, but growth in the bioplastics sector is not the only factor keeping petrochemical fans up at night.

The ocean pollution crisis has sparked more interest in reclaiming and recycling old plastic, and next-generation recycling methods are beginning to reach beyond simple melting or shredding to reach deep into the molecular level. The result is a high quality product that can be indistinguishable from virgin feedstocks.

Shell, for one, appears to see the market for fossil fuels and petrochemicals shrinking. The company has been moving forward with a new petrochemical plant in the US, but it is also hedging its bets with a new  pyrolysis-based recycling method.

Aside from recycling, the less-is-more sensibility is seeping into public consciousness, and manufacturers are responding to the growth in consumer interest over eliminating single-use plastics altogether, whether bio-based or not.

Another factor is the movement toward refillable packaging by leading consumer products firms, one good example being the Japanese company Kao.

The zero waste movement also appears to be gathering steam. Last year a company called The Loop began a delivery service for household products based on the “milk person” model of refillable containers, in partnership with UPS. It has already attracted the interest of conventional brands including Glad, Oral B, and Tide, along with Seventh Generation and other sustainability-focused companies.

Then there’s the threat from other packaging materials that could be recycled more economically than plastic. Recycled glass, for one, is getting a high tech makeover from a company called Pace Glass, so stay tuned for more on that.

Circling back around to those ethylene-producing microbes, other microbial pathways for bio-based plastics are also emerging, including our old friends cyanobacteria and E. coli.

Also, did we mention a new global sustainability initiative called the Plastics Pact, which just enlisted the US as a member.

It sure looks like the petrochemical  industry better get moving on those growth markets before they evaporate.

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Image (cropped): “Scientists have discovered how microbes in waterlogged soils produce high levels of ethylene, which can adversely affect agricultural crops and bioenergy feedstocks like switchgrass. This new knowledge can be used to develop treatments for healthier crops (credit: Andy Sproles/ORNL, U.S. Dept. of Energy).

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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

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