Composition and influencing factors of bacterial communities in ballast tank sediments: Implications for ballast water and sediment management.

This study aims to reveal the composition and influencing factors of bacterial communities in ballast tank sediments. Nine samples were collected and their 16S rRNA gene sequences were analyzed by high-throughput sequencing. The analysis results showed the Shannon index in ballast tank sediments was in the range of 5.27-6.35, which was significantly higher than that in ballast water. Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and Proteobacteria were the dominant phyla and accounted for approximately 80% of all 16S rRNA gene sequences of the samples. Besides, the high contents of sulfate reducing bacteria (SRB) and sulfur oxidizing bacteria were detected in sediments, indicating that the corrosion of metal caused by SRB might occur in ballast tank. In addition, the trace of human fecal bacteria and candidate pathogens were also detected in ballast tank sediments, and these undesirable microbes reduced the effect of ballast water exchange. Furthermore, C and N had significant effects on the bacterial community composition in ballast tank sediments. In conclusion, our findings suggest that the proper management and disposal of the ballast tank sediments should be considered in order to reduce the negative impact and ecological risks related to ballast water and sediments.