A new moderately halophilic methanotroph of the genus Methylobacter

摘要

The occurrence of methanotrophic bacteria in the sediment microflora of saline water bodies of Ukraine and Buryatia was shown by the polymerase chain reaction (PCR) technique, A new moderately halophilic methanotroph (strain 10S) capable of growing at NaCl concentrations from 0.2 to 9% was isolated from mud of Lake Sasyk (the Crimea) with a salinity of 14% NaCl. Cells of this strain are gram-negative monotrichous rods with the intracytoplasmic membranes of morphotype I. The bacterium is a mesophitic, neutrophilic obligate methanotroph possessing the ribulose monophosphate pathway of formaldehyde assimilation: its tricarboxylic acid cycle is blocked at the level of the 2-oxoglutarate dehydrogenase complex; the glyoxylate cycle is lacking. Peculiarities of the bacterium are formation of an S layer and a high content of C_(16:0) fatty acids (more than 70%). The G+C content of DNA is 46.2 mol %. Data obtained by PCR performed with the genus-specific primers mb 1007r and mm 1007r allow strain 10S to be assigned to the genus Methylobacter. Based on pheno- and genotypic characteristics, we propose a species name Methylobacter modestohalophilus for this strain. A taxonomic description of the new species is presented.