Polyphasic characterization of and genomic insights into a haloalkali-tolerant Saccharibacillus alkalitolerans sp. nov., that produces three cellulase isozymes and several antimicrobial compounds

• Published in: Antonie van Leeuwenhoek 2021-07, Vol.114 (7), p.1043-1057
• Main Authors: Darji, Himanshu, Verma, Neha, Lugani, Yogita, Mehrotra, Priyam, Sindhu, Dev Kant, Vemuluri, Venkata Ramana
• Format: Article
• Language: English
• Subjects: Antiinfectives and antibacterials; Antimicrobial agents; Biomedical and Life Sciences; Carboxymethylcellulase; Cardiolipin; Catalase; Cellulase; Fatty acids; Genes; Genomes; Isoenzymes; Life Sciences; Lipids; Medical Microbiology; Microbiology; New species; Original Paper; Phosphatidylethanolamine; Phosphatidylglycerol; Phylogeny; Plant Sciences; Quinones; rRNA 16S; Salinity tolerance; Sodium chloride; Soil Science & Conservation; Streptococcus infections; Urease
• ISSN: 0003-6072; 1572-9699
• DOI: 10.1007/s10482-021-01575-x

A cellulase producing novel bacterial strain VR-M41 T was isolated from an open-air vegetable and fruit market. Cells are found to be rod-shaped, endospore forming, positive for Gram’s stain and negative for catalase, oxidase and urease. Strain VR-M41 T  was halotolerant (upto 8.0% NaCl, w/v), motile and facultative anaerobe. It grew at wide range of pH (6.0–10.0) and temperatures (20–40 °C). Strain VR-M41 T produced three isozymes of Carboxymethylcellulase. The 16S rRNA gene sequence of strain VR-M41 T  was 97.3% similar to both  Saccharibacillus kuerlensis  DSM 22868 T and  Saccharibacillus sacchari  DSM 19268 T , and less than 96.4% with the rest of the valid species of the genus Saccharibacillus . Whole-genome ANI, dDDH and genome phylogenetic tree analysis revealed that strain VR-M41 T significantly differed from Saccharibacillus kuerlensis  DSM 22868 T and  Saccharibacillus sacchari  DSM 19268 T (ANI 79.6–79.7% and dDDH 23.1%). The strain comprised of MK-7 and anteiso-C 15:0 (42.2%) as predominant isoprenoid quinone and fatty acid respectively. Major polar lipids were found to be diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The draft genome of strain VR-M41 T consisted of 5,386,426 base pairs with 5103 annotated genes, out of which 2147 corresponded to hypothetical proteins and 2956 with functional assignments. Pan-genome analysis revealed the presence of 2998 core genes, 828 accessory genes, and 1131 unique genes of Saccharibacillus . Strain VR-M41 T produced antimicrobials against Staphylococcus aureus , Streptococcus pneumoniae , Micrococcus luteus and Shigella flexneri . Significant phenotypic and genotypic differentiating characteristics from closely related species, indicated that strain VR-M41 T is a novel species of the genus  Saccharibacillus, for which the name  Saccharibacillus alkalitolerans  sp. nov., is proposed. The type strain is VR-M41 T (= KCTC 43183 T =NBRC 114337 T ). Graphic Abstract