Spatio-temporal variation of bacterial community structure in two intertidal sediment types of Jiaozhou Bay

Abstract

AbstractThe intertidal sediment environment is dynamic and the biofilm bacterial community within it must constantly adjust, but an understanding of the differences in the biofilm bacterial community within sediments of different types is still relatively limited. In this study, the structure of the bacterial community in Jiaozhou Bay sediment biofilms are described using high-throughput 16S rRNA gene sequencing and the effects of temporal change and different sediment environment types are discussed. The Shannon index was significantly higher in sandy samples than in muddy samples. The co-occurrence network was tighter and more species were involved in community building in sandy samples. The principal coordinates analysis identified a significant separation between different sediment types and between stations (LiCun estuary, LC and ZhanQiao Pier, ZQ). Proteobacteria, which had a relative abundance of approximately 50% at all phylum levels, was significantly more abundant at ZQ, while Campilobacterota and Firmicutes were significantly more abundant at LC. The relative abundances of Bacteroidetes, Campilobacterota, Firmicutes, and Chloroflexi were significantly higher in the muddy samples, while Actinobacteria and Proteobacteria were higher in the sandy samples. There were different phylum-level biomarkers between sediment types at different stations. There were also different patterns of functional enrichment in biogeochemical cycles between sediment types and stations with the former having more gene families that differed significantly, highlighting their greater role in determining bacterial function. The RDA results, where each month’s samples were concentrated individually, showed reduced variation between months when the amplicon sequence variant was replaced by KEGG orthologs, presumably the temporal change had an impact on shaping the intertidal sediment bacterial community, although this was less clear at the gene family level. Random forest prediction yielded a combination of 43 family-level features that responded well to temporal change, reflecting the influence of temporal change on sediment biofilm bacteria.HighlightsSandy sediments have more bacterial species involved in community building.Different substrates from different stations have their own phylum biomarkers.Substrates have a greater influence on shaping bacterial function.Temporal changes have a greater shaping power on bacteria than on gene families.Graphic abstract