Properties of Hyper-Barophilic Bacteria Isolated from the Mariana Trench at a Depth of 11,000 m

Abstract

Two kinds of obligate barophilic bacteria were isolated from the world’s deepest sediment samples, obtained by a new unmanned submersible “KAIKO” in the Mariana Trench at a depth of 11,000m. The first strain (DB21MT-2) appears to be closely related to the branch of the genus Shewanella defined as the “barophiles branch”. The second strain (DB21MT-5) was closely related to the genus Moritella. The optimal growth pressure conditions of isolates were 70 MPa for strain DB21MT-2 and 80 MPa for strain DB21MT-5, no growth was detected up to 50 MPa in either strain. Thus we call these barophilic strains “hyper-barophilic bacteria”. This is the first evidence of the existence of an obligate barophilic Moritella sp. from the deep-sea environment. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.