Study On The Characteristics Of Attached Bacterial Communities In Coast Of Haikou Bay

Surface-attached marine microorganisms widely adhere on the surfaces of all types of submerged artificial facilities.In addition,the initial adhesion of bacteria on the material surface is an important stage in the process of biofouling and microbial corrosion.In this paper,the in situ experiments of suspending plates were conducted at Haikou Bay(the South China sea).After collecting the samples of bacterial communities on different materials and coatings,high-throughput sequencing technology was used to analyze the community structure.At the level of community,the influence of substrates and the main ecological factors on fouling bacteria were analyzed,and the correlations of macrofoulers attachment and bacterial communities were studied.The main experimental results are as follows:(1)The common maritime engineering materials.polymethylmethacrylate(plexiglass).soda lime glass(slide glass)and fiber reinforced plastic(fiberglass)were used in situ experiments.It was found that the structures of bacterial communities on three substrates were different.The number of operational taxonomic units(OTUs)and species richness were positively correlated with hydrophilicity of materials.The relative abundances of functional genes related to the metabolic pathways of the communities were also different.Compared to slide glass and fiberglass,plexiglass showed the best antifouling effects.(2)Compared to fiberglass,on the two antifouling coatings,the number of OTUs,richness and diversity of bacterial communities were decreased.Methylotenera,Rhodovulum and SM1A02 were the dominant genus of the communities on fiberglass,antifouling coating I and antifouling coating 2,respectively.For the functional prediction of attached bacterial communities,the relative abundance of functional genes which related to cell process and environmental information Processing coating were the highest on antifouling coating 1,while the relative abundance of lipid metabolism and carbohydrate metabolism pathways on antifouling coating 2 were the highest.Compared with that on the fiberglass,the richness and diversity of the bacterial communities on coatings were reduced,and the metabolic functions of the communities were changed,so the two coatings played important roles in the aspect of antifouling.(3)Compared with the area without macrofouling organisms,the richness and diversity of bacterial communities were increased after settlement of Amphibalanus reticulatus or Hyotissa hyotis.After the settlement of Hydroides elegants the diversity of bacterial community was higher than that on the area without settlement on all four substrates,but the richness of bacterial communities on fiberglass was lower.Moreover,on the initial settlement area of the three macrofouling species,similarities between bacterial communities attached to the material surfaces were higher than that on unsettlement area.With the settlement of three kinds of macrofoulers,the relative abundances of Methylotenera were decreased,but Loktanella were increased.The relative abundances of uncultured-bacterium-f-Rhodobacteraceae were increased after attachment of A.reticulatus and H.hyotis.Bacterial community on the surface of the material could provide attach conditions for macrofoulers.The bacterial communities varied with species of macrofouling,and metabolic functions of communities were also varied.(4)Among ecological environmental factors,the contents of dissolved oxygen and chlorophyll a were highly correlated with the species composition of the bacterial communities,but the contents of salinity and nitrate nitrogen were less correlated.The influences of environmental factors on different dominant species of bacterial communities were correlated with the evolutionary distance between species of bacteria.