Insights into the Degradation Behavior of Submicroplastics by Klebsiella pneumoniae

In the environment, micro and sub-microplastics are involved in multiple processes; however, information regarding the effect of pathogen microorganisms, or aging on the behavior of microplastics, sub-microplastics and nanoplastics still needs examination. This study examined the degradation properties of sub-microplastics with one of the clinically important pathogens, Klebsiella pneumoniae. Various concentrations of sub-microplastics were aged with K. pneumoniae to improve understanding of the degradation process. Research results revealed that K. pneumoniae broke down the sub-microplastics; functional group indices showed that the most influenced functional groups in the surface were carbonyl, carbon–oxygen and vinyl groups; and the oxygen to carbon ratio were increased while the hydroxyl groups and crystallinity were not significantly affected. The breakdown was obtained in the lower particle sizes and with additive samples. Furthermore, biochemical response of K. pneumoniae was investigated and the optical density results indicated that the tested microorganism was activated with the sub-microplastics (2–43%), except the lowest concentration of S1 and S2 at 40 h aging, and their protein response played a more effective role in the activation than carbohydrate. The results also indicated that particle size, and breakdown particles influenced the activation level.