Research of a Piezotolerant Bacteria and its Extracellular Proteases from the Deep-sea Water of the South China Sea

The deep ocean piezosphere accounts for approximately 75% of the total ocean volume, hosts active and diverse microbial communities which play a significant role in the global ocean carbon cycle. Evidence obtained thus far suggests that piezophilic microorganisms play an important role in depolymerization of marine macromolecules—transformation of particulate organic matter and production of dissolved organic matter during the slowly sinking of particulates from the surface ocean. In our research, we isolated and cultivated a mesophilic and piezotolerant bacteria. The organism's optimal growth pressure was 0.1 MPa which was lower than that at the depth of isolation and its optimal growth temperature was higher than that at the depth of isolation. What is more, when cultivated on plates composed of gelatin and starch separately, the colonies showed hydrolytic zone. Importantly, the organism showed different hydrolytic activity under different hydrostatic pressures. Our goal is to address the important biogeochemical processes in the deep ocean carbon cycle.