Characterization of Acetonitrile-Tolerant Marine Bacterium Exiguobacterium sp SBH81 and Its Tolerance Mechanism

Ajiraporn Kongpol

Katou Junichi

Tajima Takahisa

Alisa S.Vangnai

Microbes and Environments

A Gram-positive marine bacterium, Exiguobacterium sp. SBH81, was isolated as a hydrophilic organic-solvent tolerant bacterium, and exhibited high tolerance to various types of toxic hydrophilic organic solvents, including acetonitrile, at relatively high concentrations (up to 6% [v/v]) under the growing conditions. Investigation of its tolerance mechanisms illustrated that it does not rely on solvent inactivation processes or modification of cell surface characteristics, but rather, increase of the cell size lowers solvent partitioning into cells and the extrusion of solvents through the efflux system. A test using efflux pump inhibitors suggested that secondary transporters, i.e. resistance nodulation cell division (RND) and the multidrug and toxic compound extrusion (MATE) family, are involved in acetonitrile tolerance in this strain. In addition, its acetonitrile tolerance ability could be stably and significantly enhanced by repetitive growth in the presence of toxic acetonitrile. The marked acetonitrile tolerance of Exiguobacterium sp. SBH81 indicates its potential use as a host for biotechnological fermentation processes as well as bioremediation.

organic-solvent tolerant bacteria

organic-solvent tolerant mechanisms

cell adaptation

Exiguobacterium

Biology [ 460 ]

eng

Japanese Society of Microbial Ecology, Department of Bioresource Science

(c) 2012 the Japanese Society of Microbial Ecology (JSME) / the Japanese Society of Soil Microbiology (JSSM). All Rights are Reserved.

[ISSN] 1342-6311

[DOI] 10.1264/jsme2.ME11228

[NCID] AA11551577

[DOI] http://dx.doi.org/10.1264/jsme2.ME11228