The School of Chemical Engineering at Tianjin University has developed a mixed-bacteria system capable of “eating” plastic

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Source: Wenjin Author: Jiang Shan Reporter at Wenjin: Jiang Shan Empty mineral water bottles and plastic waste in the oceans… these are all types of waste that are difficult to decompose in nature, and they pose a threat to the Earth’s environment. Traditional methods for dealing with plastic waste are energy-intensive and cause significant pollution. Recently, a team of undergraduates from the School of Chemical Engineering at Tianjin University developed an \"efficient biological plastic degradation system based on a mixed-bacteria approach\", which enables the on-site decomposition of plastic waste by feeding bacteria to consume the plastic. This research achievement recently won the gold award at the 2016 International Genetically Engineered Machine Competition (iGEM), hosted by MIT in the United States. 　　A mixed-bacteria system is an artificially designed bacterial organization, akin to a \"small society\" of bacteria, where different species perform their respective roles. Some of the bacteria in the system break down the large molecules in plastic into smaller ones, while other bacteria either absorb these smaller molecules or convert them into other useful substances. 　　“It’s easy to say, but it’s not possible for humans to ‘communicate’ directly with bacteria; there’s no way to tell them when they should exhibit the functions designed by humans. Moreover, the survival capabilities of different bacterial strains vary greatly, and often the dominant strains will steal nutrients from other strains, eliminating them all and resulting in a situation where one strain dominates everything. ”The project members said. 　　Through hundreds of mixed-bacteria experiments to continuously explore the conditions for bacterial cultivation, the students ultimately succeeded in developing a mixed-bacteria system that allows different bacterial species to coexist peacefully. They ingeniously designed a metabolic pathway in the mixed microbial system, reducing competition among the microbes for nutrients and thereby achieving stability in the system. “This mixed microbial system is capable of completely breaking down common plastics used in daily life; by releasing this microbial mixture into the natural environment, it can effectively degrade polyester plastics that would otherwise remain unchanged for thousands of years, offering the potential for on-site decomposition of plastic waste. ”The project members said. 　　Ask the Editor, Zhao Ying