Characterization of Marine Bacteria for Bioplastic Degradation in Ocean Environments

Plastic pollution is one of the biggest environmental issues, specifically its impact in ocean environments. Nearly 1-2 million tonnes of plastic waste ends up in the ocean every year, harming the environment by disrupting ecosystems, breaking down into microplastics, and releasing toxic chemicals. Bioplastics offer a viable alternative to traditional petroleum plastics because of their ability to biodegrade. However, most bioplastics require specific conditions, such as warm, low oxygen environments, which are not present in marine environments naturally, in order to properly break down. Poly(3-hydroxybutyrate) (PHB) has been discovered as a naturally occurring polymer that can be used as an alternative plastic material. It is produced by bacteria as an energy storage molecule and can be metabolized in the Krebs cycle, therefore does not produce any harmful waste. Moreover, some strains of bacteria have developed the ability to break down PHB produced by other cells. Research has shown that synthetic biology can be used to take advantage of the PHB degrading properties of these strains to accelerate the rate of degradation of ocean plastics. Thus, they continue to be investigated to find possible applications and uses for a sustainable plastic alternative.

PHB-degrading bacteria strains were collected on submersed sample discs off the coast of California in the Santa Barbara Basin and the UCSB Lagoon. These bacteria strains were then analyzed and characterized in order to determine further specific applications. Plate readers were used to determine the growth rate for each strain. A 3D bioprinting technology developed in the Meyer Lab was used to create hydrogel based “biostickers” that allow for stabilization and longevity of the cells, as well as controlled analyses and applications of these strains to PHB products. Additionally, PHB degradation experiments via clear-zone analysis were conducted with the biostickers on PHB-powder agar plates at different temperatures to determine the rate of degradation. To determine the best conditions for performing long term experiments, humidity conditions were varied. The results showed various growth patterns which will allow for different applications of the bacteria, such as use for PHB degradation at different ocean depths or intended lifespan of PHB products. Furthermore, storing the degradation tests in a box with a beaker of autoclaved water has proven to be the best set up to prevent plates from drying out.