Engineered Bacteria Process Converts Bio-Wastes to Plastics

(Agricultural Research Service/USDA)

A Ph.D. candidate at Delft University of Technology (TU Delft) in the Netherlands has discovered a process for engineering bacteria to more efficiently convert agricultural wastes into industrial-quality plastics. Jean-Paul Meijnen presented the findings in his dissertation, which he defends at TU Delft on Monday 22 November.

Lignocellulose, the complex combination of lignin and cellulose present in the stalks and leaves of plants that gives them their rigidity, is also found in plentiful quantities as unused waste that provides the raw material for bioplastics. Breaking down the long sugar chains that form the backbone of this material releases the individual sugar molecules that can be further processed by bacteria and other micro-organisms into chemicals that can be used as the basis for bioplastics.

Three of those sugars — glucose, xylose, and arabinose — make up about eighty per cent of the sugars in bio-waste. Meijnen found that the bacteria he was using could ingest only the glucose, which accounted for about a quarter of the available raw material. He then genetically engineered the bacteria to produce more enzymes that digested xylose and arabinose.

Through accelerated evolution and the introduction of genes from other bacteria, Meijen was then able to engineer and select enough organisms to digest the sugars from bio-wastes in sufficient quantities. This process led to production in the lab of a member of the class of chemicals known as parabens that are widely used as preservatives in the cosmetics and pharmaceutical industries.

Meijnen’s study was financed by the Bio-based Sustainable Industrial Chemistry Consortium (B-Basic) and the Netherlands Association for Scientific Research. B-Basic is a group of Dutch universities, research institutes, and companies for the sustainable production of energy and chemicals.

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