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Sustainable Bioplastics Produced from Microbes, Algae

Ulva or sea lettuce

Ulva or sea lettuce (H. Krisp, Wikimedia Commons)

26 Dec. 2018. Researchers in Israel showed in lab tests the feasibility of producing biocompatible and degradable plastics from ocean microbes and algae. Environmental science and chemistry groups at University of Tel Aviv describe their process and findings in the January 2019 issue of the journal Bioresource Technology.

The team led by Tel Aviv environmental scientist Alexander Golberg and chemistry professor Michael Gozin are seeking better solutions to a growing ecological problem of plastic accumulations in landfills and oceans. The authors cite data from 2017 showing 320 million metric tons of plastic worldwide are consumed each year, with fewer options available for processing discarded plastic. As reported in Science & Enterprise, China now imports more than 72 percent of the world’s plastic waste, but in 2030, will no longer take in discarded plastic. As a result, alternatives to current plastic products, as well as methods for their production and recycling are urgently needed.

Most common polymer plastics have long been made from petroleum derivatives, but many of these polymers can also be made from non-petroleum organic sources such as plants. These bioplastics, however, still have their environmental price tags, namely the need for arable land and fresh water, which in countries like Israel, are in limited supply. As a result, the researchers investigated alternatives to plant-based bioplastics. “Our new process,” says Golberg in a university statement, “produces ‘plastic’ from marine microorganisms that completely recycle into organic waste.”

The solution devised by Golberg, Gozin, and colleagues uses this process to produce polyhydroxyalkanoates, or PHAs, a polymer derived from biomaterials. But PHAs are also biodegradable, which means they’re ingested and broken down by microbes in soil or water, reducing their imposition on the environment. This biodegradable quality makes PHAs useful as well for sutures and single-use or implanted medical devices. Nonetheless, PHAs have their down sides, namely poor mechanical properties and susceptibility to thermal degradation.

PHAs are made by microorganisms ingesting and fermenting plant matter, so the researchers investigated microbes that feed on seaweed, a common form of marine plant life that neither grows on land nor needs fresh water. The researchers tested 7 types of seaweed consumed by Haloferax mediterranei, a salt-water bacterium found as the name suggests in the Mediterranean. The team found a form of marine algae called ulva produces the most PHA material. Ulva is a simple seaweed algae, also known as sea lettuce, which while edible is sometimes considered a nuisance, when it grows and accumulates around sewage treatment plants.

The Tel Aviv team says it proved the concept and demonstrated the feasibility of making PHAs in a more sustainable way. “We have proved it is possible to produce bioplastic completely based on marine resources in a process that is friendly both to the environment and to its residents,” notes Golberg. “We are now conducting basic research to find the best bacteria and algae that would be most suitable for producing polymers for bioplastics with different properties.”

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