Bacillus ligniniphilus sp. nov., an alkaliphilic and halotolerant bacterium isolated from sediments of the South China Sea.

An alkaliphilic and halotolerant Gram-stain-positive bacterium, which was isolated from sediment samples from the South China Sea, was subjected to a taxonomic study. The isolate, strain L1T, grew well at a wide range of temperatures and pH values, 10.0-45.0 °C and pH 6-11, with optima at 30 °C and pH 9.0, respectively. The growth of strain L1T occurred at total salt concentrations of 0-10% (w/v) with an optimum at 2% (w/v). Phylogenetic analysis based on 16S rRNA sequence comparison indicated that the isolate represented a member of the genus Bacillus. The strains most closely related to strain L1T were Bacillus nanhaiisediminis JCM 16507T, Bacillus halodurans DSM 497T and Bacillus pseudofirmus DSM 8715T, with 16S rRNA similarities of 96.5%, 95.9% and 95.7%, respectively. DNA-DNA hybridization of strain L1T with the type strains of the most closely related species, B. nanhaiisediminis JCM 16507T, B. halodurans DSM 497T and B. pseudofirmus DSM 8715T, showed reassociation values of about 21.7%, 14.3% and 13.9%, respectively. The DNA G+C content of strain L1T was 40.76 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant cellular fatty acids of strain L1T were iso-C14 : 0 and anteiso-C15:0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Based on the phenotypic and phylogenetic characteristics, it is proposed that strain L1T (=JCM 18543T=DSM 26145T) should be classified as the type strain of Bacillus ligniniphilus sp. nov.

Bacterial community composition of South China Sea sediments through pyrosequencing-based analysis of 16S rRNA genes.

BACKGROUND: Subseafloor sediments accumulate large amounts of organic and inorganic materials that contain a highly diverse microbial ecosystem. The aim of this study was to survey the bacterial community of subseafloor sediments from the South China Sea. METHODOLOGY/PRINCIPAL FINDINGS: Pyrosequencing of over 265,000 amplicons of the V3 hypervariable region of the 16S ribosomal RNA gene was performed on 16 sediment samples collected from multiple locations in the northern region of the South China Sea from depths ranging from 35 to 4000 m. A total of 9,726 operational taxonomic units (OTUs; between 695 and 2819 unique OTUs per sample) at 97% sequence similarity level were generated. In total, 40 bacterial phyla including 22 formally described phyla and 18 candidate phyla, with Proteobacteria, Firmicutes, Planctomycetes, Actinobacteria and Chloroflexi being most diverse, were identified. The most abundant phylotype, accounting for 42.6% of all sequences, belonged to Gammaproteobacteria, which possessed absolute predominance in the samples analyzed. Among the 18 candidate phyla, 12 were found for the first time in the South China Sea. CONCLUSIONS: This study provided a novel insight into the composition of bacterial communities of the South China Sea subseafloor. Furthermore, abundances and community similarity analysis showed that the compositions of the bacterial communities are very similar at phylum level at different depths from 35-4000 m.

Genome Sequence of the Alkaliphilic Bacterial Strain Bacillus ligninesis L1, a Novel Degrader of Lignin.

Bacillus ligninesis strain L1, isolated from seafloor sediment, was able to grow on medium with lignin as its sole carbon source. Here, we report a 3.8-Mbp high-quality genome sequence for this bacterium. The genes involving ectoine and glycine betaine synthesis, as well as those involved in the degradation of lignin, were identified.