Diversity of culturable attached-living bacteria from North Sea sediment
Mayanna, S. (2010). Diversity of culturable attached-living bacteria from North Sea sediment. MSc Thesis. Erasmus Mundus Master of Science in Marine Biodiversity and Conservation (EMBC)/Max Planck Institute for Marine Microbiology: Bremen. 58 pp.
Bacteria may be one of the most abundant and species-rich group of organisms, and they mediate many vital ecosystem processes. Notably, attached-living bacteria are often larger, more versatile and are present in higher local concentrations than free-living bacteria in water. However, lack of sophisticated culture techniques hampers the isolation and diversity of attached-living sediment bacteria. In this study, the microbial community composition of Wadden Sea sediments of the German North Sea coast was investigated by culture-dependent and -independent techniques. Likely to winter condition with ambient temperature below zero, we recovered by direct plating approximately 10^4 CFU mL-1 of sediment, which was 10^4 times lower than previous studies. Analysis of 16S rRNA gene sequences from cultures revealed a high diversity of bacteria affiliated within the Gammaproteobacteria, Bacteroidetes, Alphaproteobacteria and Firmicutes. The most abundant classes of isolates from Wadden Sea sandy sediment were Gammaproteobacteria (61 %) and Alphaproteobacteria (24 %). A novel incubation approach to isolate diverse group of bacterial communities through 16S rRNA gene sequences yielded only a member of the Vibrionaceae. The frequent isolation of fast growing groups of Vibrionaceae suggests an especially efficient adaptation to the rapid temperature shift from below zero to 20 0C. However, our high throughput approach yielded also many slowly growing/less-active isolates and kanamycin resistant yellow or orange pigmented colonies. From 153 yellow or orange pigmented isolates 83 % were affiliated to the family Flavobacteriaceae.
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