Screening And Diversity Analysis Of Natural Polymer Organic Matter Degrading Bacteria In Offshore Marine Environment

Marine bacteria play an important role in the mineralization of organic matter and the earth's carbon cycle.Offshore is the connection zone between the land and the ocean.Although the area is much smaller than that of the ocean,the biogeochemical processes occurring in it are more complicated than that of the ocean.When Marine plants and animals die,hard-to-degrade tissue components may end up buried in sediments,and what groups of bacteria are involved in their degradation in the in-situ Marine environment is an urgent question to be addressed.To answer this question,we selected five macromolecular polymers or natural tissues of Marine animals and plants: shrimp shells,fish scales,kelp leaves,chitin and chitosan.Through the screening of organic-degrading bacteria,abundant resources and high proportion of new species were obtained.Enrichment was carried out in seawater surface and sediment,samples were taken regularly,and the diversity of bacteria was analyzed by high-throughput sequencing.The results showed that the diversity of bacteria enriched by different organics in situ was significantly different,and the biodegradability of the same substrates in seawater surface and sediment was significantly different.After 30 days of sample enrichment,the species diversity of fish scale samples in the surface environment was the most abundant,while the diversity of kelp samples in the sediments was the lowest.In addition to the dominant bacteria of kelp outside the door of Thermophore,the remaining samples were mainly Proteobacteria,and Desulfobacteraceae,Flavobacteriaceae,Desulfovibrionaceae and Vibrioaceae accounted for a large proportion.The abundance of Desulfobacteraceae bacilli was higher in all samples,while that of Flavobacteriaceae was dominant in seawater surface environment samples,and that of Vibrioaceae in sediment samples was highest in chitin and chitosan,which were 26.3% and 7.5%,respectively.The microbiota structures of fish scale samples after different enrichment time were also compared.It was found that Marinifilum had the highest abundance in fish scale samples,and the abundance gradually decreased with the increase of enrichment time.There were significant differences in the flora structure and abundance of fish scale samples at different stages,in which the abundance of Proteobacteria increased with the enrichment time,while the abundance of clostridium decreased.At the same time,we also used organic matter as the only carbon source to carry out enrichment analysis of its flora structure under laboratory conditions,and obtained that the enrichment results in laboratory were significantly different from those in situ.This study enriched the offshore bacterial resources by selecting culturable bacteria from enriched samples.The results of high-throughput sequencing analysis reflect the characteristics of the flora involved in the degradation of organic compounds,which will help us understand the bacterial mineralization process of refractory macromolecules of natural organic compounds in the offshore environment,and provide references for the evaluation of the role of organic compounds mineralization and Marine carbon cycle.