Halobacillus rhizosphaerae sp. nov., a moderately halophilic bacterium with protease activities isolated from the rhizosphere soil of the mangrove Acanthus ebracteatus

• Published in: Antonie van Leeuwenhoek 2025-01, Vol.118 (1), p.31, Article 31
• Main Authors: Yin, Doudou, Xie, Junjie, Liu, Rui, Song, Chaodong, Liang, Ying, Huang, Hongzhi, Huang, Yihui, Long, Ruiting, Shen, Naikun, Yan, Bing, Zhang, Hongyan
• Format: Article
• Language: English
• Subjects: Acanthaceae - microbiology; Acanthus ebracteatus; Bacterial Typing Techniques; Base Composition; Biomedical and Life Sciences; Cardiolipin; Casein; China; Curing agents; Deoxyribonucleic acid; DNA; DNA sequencing; DNA, Bacterial - genetics; Fatty Acids - analysis; Fatty Acids - metabolism; Gene sequencing; Halobacillus - classification; Halobacillus - genetics; Halobacillus - isolation & purification; Halobacillus - metabolism; Hybridization; Life Sciences; Lipids; Medical Microbiology; Microbiology; New species; Nucleotide sequence; Nucleotides; Original Paper; Peptide Hydrolases - genetics; Peptide Hydrolases - metabolism; Peptidoglycans; Phosphatidylglycerol; Phospholipids; Phospholipids - analysis; Phylogenetics; Phylogeny; Plant Sciences; Protease; Proteinase; Quinones; Rhizosphere; RNA, Ribosomal, 16S - genetics; rRNA 16S; Salinity tolerance; Sequence Analysis, DNA; Sodium chloride; Sodium Chloride - metabolism; Soil bacteria; Soil Microbiology; Soil microorganisms; Soil Science & Conservation; Strain analysis
• ISSN: 0003-6072; 1572-9699; 1572-9699
• DOI: 10.1007/s10482-024-02040-1

A Gram-positive, moderately halophilic, rod-shaped and facultatively anaerobic strain T66 T , was isolated from the rhizosphere soil of mangrove Acanthus ebracteatus in Guangxi, China. Strain T66 T was observed to grow at 15–40 ℃ (optimum 30 ℃), pH 5–8 (optimum 6–7) and with 2–20% (w/v) NaCl (optimum 6%). The phylogenetic tree of the 16S rRNA gene sequences depicted a cluster of strain T66 T to be closely related to Halobacillus litoralis SL-4  T (98.72%), Halobacillus dabanensis D-8  T (98.70%) and Halobacillus campisalis ASL-17  T (98.66%). The phylogenetic analysis based on the 16S rRNA gene sequence showed that strain T66 T belonged to the genus Halobacillus and formed a separate branch. The digital DNA-DNA hybridisation and average nucleotide identify values between strain T66 T and its related species were 17.80–19.80% and 70.78–73.22%, respectively, which were lower than the threshold recommended for species delineation. The genomic DNA G + C content was 40.9%. The predominant isoprenoid quinone was MK-7, the cell-wall peptidoglycan contained meso-diaminopimelic acid, and the major fatty acids that accounted for more than 10.0% were anteiso-C 15:0 (68.4%) and anteiso-C 17:0 (13.4%). Phosphatidylglycerol, diphosphatidylglycerol, three unidentified phospholipids and an unidentified glycolipid were found in the polar lipid extraction. Strain T66 T could hydrolyse casein and contains several genes (e. g. vanY, vpr, pbpG and elpC ) involved in protease. Therefore, strain T66 T is salt-tolerant and produces protease, and it may have development and utilisation value in flavouring agents and food curing. Based on phenotypic, chemotaxonomic data and genotypic characteristics, strain T66 T represents a novel species of the genus Halobacillus , for which the name Halobacillus rhizosphaerae sp. nov. is proposed. The type strain is T66 T (= JCM 36534  T  = MCCC 1K08701 T ).