Caldicellulosiruptor changbaiensis sp. nov., a cellulolytic and hydrogen-producing bacterium from a hot spring

Abstract

A novel thermophilic bacterial strain, CBS-ZT, was isolated from a terrestrial hot spring in the Changbai Mountains, PR China. Cells of strain CBS-ZT were short straight rods without flagella and had Gram-positive cell walls. Growth was observed at 40–90 °C (optimum 75 °C) and at pH 5.6–8.6 (optimum pH 7.8). The primary end-products from the fermentation of filter paper by strain CBS-ZT were acetate, lactate, H2, and CO2. The main cellular fatty acids were iso-C17 : 0, iso-C14 : 0 3-OH and C16 : 0. The G+C content of the genomic DNA was 36.08 mol%. Multiple sequence alignment of the 16S rRNA gene sequence and phylogenetic analyses indicated that strain CBS-ZT belongs to the genus Caldicellulosiruptor and the most similar micro-organism was Caldicellulosiruptor saccharolyticus DSM 8903T (96.36 % 16S rRNA gene sequence similarity); the 16S rRNA gene sequence similarity of strain CBS-ZT to other species was below 95 %. Based on its phylogenetic and phenotypic characteristics, strain CBS-ZT represents a novel species of the genus Caldicellulosiruptor , for which the name Caldicellulosiruptor changbaiensis sp. nov. is proposed. The type strain is CBS-ZT ( = DSM 26941T = CGMCC 1.5180T).