Phenotypic Characterization and Genome Analysis of a Novel Isolate of the Spiral-Shaped Methanotroph “Methylospira mobilis”

Abstract

Taxon “Methylospira mobilis” accommodates micro-aerobic, spiral-shaped methanotrophic bacteria, which are widely distributed in low-oxygen habitats. Due to difficulties of cultivation, these methanotrophs remained represented by a single isolate, strain Shm1, which was obtained from a boreal peat bog of European Russia. This study reports isolation of a novel member of this candidate genus, strain SPMX, obtained from a subarctic wetland. The 16S rRNA gene sequence of strain SPMX was identical to that in strain Shm1. The complete genome sequence of strain SPMX was 4.6 Mb in size and displayed 99.5% average nucleotide identity to the genome sequence of strain Shm1, thus suggesting affiliation of these bacteria to one methanotroph species. In contrast to strain Shm1, the new isolate was more tolerant to low temperatures and was less growth-dependent on the presence of СО₂. The genomes of both spiral-shaped methanotrophs encoded form II ribulose bisphosphate carboxylase, which makes them different from the majority of other type X methanotrophs that possess form I of this enzyme.