Effect of different depressurization process on cultivable bacterial community composition of deep-sea water

Abstract:

[Objective] The aim of this study was to compare the effect of pressure change styles on cultivable bacteria in deep-sea water sample by controlling the different pressure change process, and discuss the cultivable bacteria abundance and community composition of Mariana trench deep-sea water sample under different depressurization process. [Methods] We sampled the uncontaminated deep-sea water at the depth of 6001 m without depressurization. Then, samples were treated with short-time fast depressurization and long-time slow depressurization. After that, bacteria were enriched in the 2216E or 2216E media added trimethylamine N-oxide (TMAO). The 16S rRNA gene of cultivable bacteria and their abundance were analyzed. [Results] Deep-sea water treated with slow and fast depressurization differed greatly in diversity and abundance of cultivable bacteria. In sample treated with slow depressurization process, the average abundance was approximately 190 CFU/mL and Bacillus was the dominant group (96% of total colonies). However, the average abundance of fast depressurized sample was approximately 437 CFU/mL, and diverse groups including Bacillus (27.8%), Achromobacter (24.4%), Microbacterium (34.4%) and Pseudomonas (13.7%) were observed. Noticeable, addition of TMAO had little effect on abundance of cultivable bacteria of both different depressurization samples, but the diversity of both samples increased and abundance of some species obviously changed.[Conclusion] Depressurization process could change the composition and abundance of cultivable bacteria in deep-sea water sample, addition of TMAO during the enrichment could increase the isolated bacterial species. These results made a solid foundation for further in-depth study of deep-sea bacteria.

Key words:deep-sea;depressurization process;cultivable bacteria;diversity;pressure-retained sampling