Research On Influencing Factors Of Biofilm Formation And Adhesion Mechanism Of Marine Bacteria

Marine biofouling has caused huge economic losses,and biofilm plays an important role in biofouling.Marine bacteria are affected by the environment during the formation of biofilm processes.Bacterial biofilm begins with the adhesion of bacteria,after the bacteria adhesion to the surface of the object can secrete extracellular polymer to enhance their adhesion,so that the bacteria firmly adhere to the substrate.At present,the research on biofilm is mainly focused on medicine,and there are few studies on the adhesion of marine bacteria and the formation of marine bacterial biofilm.In this paper,we isolated and tested the biofilm-forming capacity of marine bacteria,and the bacteria with strong capacity of forming biofilm were screened to analyze the effect of different factors on the capacity of biofilm formation.From biofilm-forming bacteria,we screened out a strain with the strongest adhesion capacity,and analyze the differentially expressed proteins between planktonic and initial adhesion bacteria,to explore the initial adhesion mechanism of the bacteria.Research results may help to analysis the bacteria on the response of the different factors in the environment,and interpret the molecular mechanism of marine bacteria adhesion to abiotic surface,and help to find new targets of antifouling agents,provide new ideas for the development of antifouling agent.The main results were shown as followed.1.51 strains of bacteria were isolated and purified from the surface of offshore artificial substrate,and 11 strains of bacteria with strong biofilm-forming capacity were screened.Among them,one OD600 was<1,and six OD600 values were between 1 and 2,there were four OD600 values>2.16S rRNA identification results showed that 1 strain belonging to the genus Leisingera,Rhodobacteraceae with 1 strain,2 strains belonging to Pseudoalteromonas,Alteromonas with 1 strain,Tenacibaculum with 2 strain,Vibrio with 1 strain,Chryseobacterium with 1 strain,Aquimarina,1 strain,Acinetobacter with 1 strain.A strain(W-7)with strong adhesion capacity was obtained from 11 strains which belonged to Pseudoalteromonas.The density was 2.4*106 cm-2 when adhesion to coverslips in 3 h with bacteria concentration of 107 mL-1.2.The effects of different temperature,salinity,pH and Cu2+ concentration on the biofilm-forming capacity of 11 bacteria were studied.It was found that these four factors could affect the formation of biofilm,but the effect on different bacteria was different.When the temperature was low,the temperature increased to promote the biofilm formation of 8 strains of bacteria,when the temperature was higher,only four strains of bacteria were inhibited;salinity increased have inhibitory effect on the biofilm formation of four strains,and all bacteria can achieve the strongest biofilm-forming capacity within 30 degrees of salinity.The impact of pH at 6.5~8.5 is relatively small,at pH 7.5?8.0 biofilm-forming capacity can reach the strongest.When Cu2+ concentration is low,the majority of bacterial biofilm-forming capacity is promoted or has no effect,When Cu2+ concentration is 1.5 mM,more than half of the bacteria can not grow normally.The response of different bacteria biofilm-forming process to the environment is different,revealing the complexity of the bacterial response to the environment.3.The results of W-7 differential protein analysis showed that 163 proteins were differentially expressed,among which 43 were up-regulated and 120 were down-regulated.GO functional analysis showed that the differentially expressed proteins were mainly distributed in the cellular processes,metabolic processes,single-organism processes,established of localization and localization under biological processes,UTP-glucose-1-phosphate uridylyltransferase,acetyltransferase component of pyruvate dehydrogenase complex,outer membrane protein and so on may play an important role in the adhesion of bacteria.