Study On ROS Production And Pollutants Degradation By Marine Bacterial Biofilms

ROS（Reactive Oxygen Species,ROS）,including H₂O₂,O₂^·-,·OH,etc.,play an important role in the transformation of various pollutants in aquatic environments.Marine microorganisms,which can produce ROS,are inferred as source of ROS for marine aphotic zones.Therefore,it’s reasonable to speculate that biological sources of ROS have vital effects on the fate of emerging pollutants.However,in the actual Marine environment.However,in the actual marine environment,microorganisms have the tendency to form into biofilms,and the effect of biofilm on ROS production has not been reported.In this study,ROS production characteristics of Pseudoalteromonas sp.GCY biofilm were investigated.The degradation characteristics and pathways of Bisphenol A（BPA）,an endocrine disruptor commonly detected in Marine environment,was also studied.Firstly,the effect of GCY biofilm on ROS production and its mechanism were studied.Both carbon foam and scallop have no toxic effects on the growth of strain GCY,and both carriers can promote the production of extracellular O₂^·-,and the carbon foam can promote the production of extracellular H₂O₂.At the same time,according to the results,the extracellular H₂O₂,O₂^·-and·OH production of GCY biofilm was higher than that of free cells.Extracellular H₂O₂ production and extracellular O₂^·-production was 3.10 times and 3.56 times higher than that of free cells,respectively.And·OH production was 1.44 times as high as that of the free cells.Meanwhile,the activities of L-amino acid oxidase,DHA and ETSA were also increased.Compared with free cells,polysaccharide and protein contents in EPS components were both increased.The total EPS production increased by 149 mg·L^-1,which enhanced cell adhesion and reduced ROS-induced damage to cells.As a typical environmental micropollutant,Bisphenol A（BPA）has been widely concerned for its endocrine disrupting effects.However,the degradation of BPA by marine bacterial biofilms has not been studied.In this study,Pseudoalteromonas sp.GCY biofilms were cultured with carbon foam to investigate the degradation of BPA by biofilms.The degradation characteristics and degradation pathways of GCY biofilms for emerging pollutants represented by BPA were studied.The results showed that compared with the free cells,the degradation efficiency of BPA in the biofilm system was improved at 72 h.And the degradation in two systems both fit the pseudo-first-order kinetics.The degradation rate constant（k）was 0.0425 by GCY biofilm,which was higher than that of free cells.The production of H₂O₂,O₂^·-and·OH by biofilms were higher than those by free cells at the same time.The activities of LAAO,iron carrier,dehydrogenase and ETSA in the biofilm systems were higher than those in the free cells systems at the same time.In the process of degradation of BPA by GCY biofilm,5 intermediates were detected,and it was inferred that the main degradation pathway of BPA was isopropyl fracture.In summary,this study confirmed that marine bacterial biofilms have higher ROS production and greater pollutant degradation efficiency,providing a new perspective for biologically derived ROS in the marine aphotic zone,and provides the basis for the comprehensive evaluation of the trend and transformation of pollutants in marine environment.