Brevibacillus humidisoli sp. nov., a moderately thermoalkaliphilic and halotolerant species isolated from riverside soil

Abstract

A Gram-stain-positive, aerobic, rod-shaped, motile, and endospore-forming bacterial strain designated MMS20-4M-10-YT was isolated from riverside soil and subjected to taxonomic characterization. Strain MMS20-4M-10-YT was moderately thermophilic, alkaliphilic and halotolerant, as the strain grew at 25–50 °C (optimum, 45 °C), at pH 7.0–10.0 (optimum, pH 8.0) and in the presence of 0–6 % NaCl (optimum, 0 %). Analysis of 16S rRNA gene sequences indicated that MMS20-4M-10-YT fell into a phylogenetic cluster belonging to the genus Brevibacillus . Strain MMS20-4M-10-YT showed the highest 16S rRNA gene sequence similarity to Brevibacillus marinus SCSIO 07484T (96.7 %). Based on the reults of orthologous average nucleotide identity analysis, MMS20-4M-10-YT was again mostly related to B. marinus SCSIO 07484T with 78.0 % identity, which also shared the highest average nucleotide identity of 68.0 %. In contrast, the digital DNA–DNA relatedness analysis indicated that Aneureibacillus migulanus DSM 2895T was the closest species with 29.5 % similarity. The genome-based analyses indicated that all compared species showed low genomic relatedness with MMS20-4M-10-YT. The major fatty acids of the strain were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0 and iso-C17 : 0, the major respiratory quinone was MK-7, the diagnostic polar lipids were phosphatidyl-N-methylethanolamine, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol, and diagnostic cell-wall diamino acid was meso-diaminopimelic acid, which was consistent with the general chemotaxonomic features of the genus. The total length of the genome was 4.91 Mbp and the DNA G+C content was 51.8 mol%. Based on both phenotypic and phylogenetic evidence, strain MMS20-4M-10-YT should be classified as representing a novel species of the genus Brevibacillus , for which a name Brevibacillus humidisoli sp. nov. (type strain=MMS20-4M-10-YT=KCTC 43333T=LMG 32359T) is proposed.