[Biodegradation of Polystyrene by Geobacillus stearothermophilus]

Biodegradation is the most sustainable treatment method for waste polystyrene (PS). Thermophiles possess highly efficient biotransformation capabilities that could enhance the biodegradation efficiency of organic solid wastes. However, detailed research on the degradation of PS plastics by thermophile is scarce. Here, the degradation performance of a strain of Geobacillus stearothermophilus FAFU011 (FAFUA011) isolated from compost was examined. The results showed that strain FAFUA011 could utilize PS as the sole carbon source for growth and formed a stable biofilm on the surface of PS fragments. During 56 days of degradation, FAFU0011 caused a total mass loss of PS of 4.2% and decrease in molecular weight of 17.4%-18.2%. Based on SEM observations, FAFUA011 causes erosion hollows on the surface of PS, thus increasing the type and number of oxygen-containing structures that alter its hydrophilic properties. These changes facilitate the colonization of other microorganisms and further promote biodegradation. Based on 2D-COS analysis, the chronological order of the change in functional groups during the degradation process were identified as follows:1491 cm^-1(C-H) > 1450 cm^-1(C-H) > 1601 cm^-1(C=C) > 1027 cm^-1(C-O) > 1068 cm^-1(C=O) > 1366 cm^-1(C-OH). Overall, these results reveal that FAFU011 could promote the thermophilic bio-oxidative degradation of PS plastic.