title: Composition of humic acid-degrading estuarine and marine bacterial communities.
abstract: We examined the bacterial decomposition of humic acids (HA) in two flow-through culture experiments, one inoculated by marine and one by estuarine bacterial communities. In both experiments, the cultures were fed with HA media of salinities of 28 and 14, close to their ambient and a distinctly different, foreign salinity. HA were decomposed to > 60% of the initial concentration within 70 days, and the foreign salinity yielded the highest decomposition. A detrended correspondence analysis of denaturing gradient gel electrophoresis (DGGE) banding patterns showed that during incubation, the bacterial community composition underwent distinct changes. A phylogenetic analysis of DGGE bands excised and bacteria isolated at the end on HA as the sole carbon source showed that Alphaproteobacteria and Gammaproteobacteria largely dominated the communities in the marine flow-through cultures, whereas Gammaproteobacteria, Actinobacteria and Alphaproteobacteria dominated the estuarine communities. Eleven of 13 isolates obtained from both experiments were able to grow on HA as the sole carbon source, seven on phenol and three, affiliated to the Roseobacter clade, on various aromatic acids. The bacteria retrieved from the flow-through cultures were closely (96-99%) affiliated to organisms capable of degrading humic matter, aromatic and aliphatic compounds and also to other bacteria reported previously from the Wadden Sea and Weser estuary.
authors: Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany.
authors: Dagmar
authors: D
authors: Rocker
authors: Thorsten
authors: T
authors: Brinkhoff
authors: Nico
authors: N
authors: Grüner
authors: Marco
authors: M
authors: Dogs
authors: Meinhard
authors: M
authors: Simon
mesh_terms: D039903:Actinobacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D020561:Alphaproteobacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D044822:Biodiversity; D058645:Denaturing Gradient Gel Electrophoresis; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D006812:Humic Substances / Q000032:analysis / Q000382:microbiology*; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D041904:Roseobacter / Q000145:classification / Q000235:genetics / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D006812:Humic Substances; D012336:RNA, Ribosomal, 16S