In situ cultivation of deep-sea water with bicarbonate fueled a different microbial community

Some deep-sea microbes may incorporate inorganic carbon to reduce CO2 emission to upper layer and atmosphere. How the microbial inhabitants can be affected under addition of bicarbonate has not been studied using in situ fixed and lysed samples. In this study, we cultivated 40 L natural bottom water at ∼1 000 m depth with a final concentration of 0.1 mmol/L bicarbonate for 40 min and applied multiple in situ nucleic acids collection (MISNAC) apparatus for nucleic acids extraction from the cultivation. Our classification result of the cultivation sample showed a distinct microbial community structure, compared with the samples obtained by Niskin bottle and six working units of MISNAC. Except for notable enrichment of Alteromonas, we detected prevalence of Asprobacter, Ilumatobacter and Saccharimonadales in the cultivation. Deep-sea lineages of Euryarchaeota, SAR406, SAR202 and SAR324 were almost completely absent from the cultivation and Niskin samples. This study revealed the dominant microbes affected by bicarbonate addition and Niskin sampling, which suggested rapid responses of deep-sea microbes to the environmental changes.