Flavobacterial response to organic pollution

Bacteria of the Cytophaga-Flavobacterium-Bacteroides (CFB) group (phylum Bacteroidetes), in particular members of the class Flavobacteria, are among the most prominent heterotrophic organisms in marine pelagic systems. They have also previously been found to be important in the initial biopolymer degradation of sedimentary organic matter. The Flavobacteria community was analysed in inshore, marine sediments subject to regular inputs of highly labile organic carbon in order to understand the importance of this group in carbon degradation. We used denaturing gradient gel electrophoresis and real-time PCR in a statistically robust manner, over 2 consecutive years, to demonstrate that the number of Flavobacteria in the sediment increased and community composition shifted with organic loading. Further community shifts occurred after cessation of organic loading, and population numbers also decreased. Flavobacteria appear to be important in the initial responses of the sediment microbial community to organic loading, regardless of sediment type, but flavobacterial composition was not predictable. The highly dynamic nature and large diversity (functional redundancy) of the Flavobacteria in these sediments may contribute to this unpredictable response.