Aureibacillus halotolerans gen. nov., sp. nov., isolated from marine sediment

A taxonomic note on the order Caryophanales: description of 12 novel families and emended description of 21 families

The order Caryophanales, belonging to class Bacilli, is globally distributed in various ecosystems. Currently, this order comprised 12 families that show vast phenotypic, ecological and genotypic variation. The classification of Caryophanales at the family level is currently mainly based on 16S rRNA gene sequencing analysis and the presence of shared phenotypic characteristics, resulting in noticeable anomalies. Our present study revises the taxonomy of Caryophanales based on 1080 available high-quality genome sequences of type strains. The evaluated parameters included the core-genome phylogeny, pairwise average aa identity, lineage-specific core genes, physiological criteria and ecological parameters. Based on the results of this polyphasic approach, we propose that the order Caryophanales be reclassified into 41 families, which include the existing 12 families, 17 families in a recent Validation List in the IJSEM (Validation List no. 215) and 12 novel families for which we propose the names Aureibacillaceae, Cytobacillaceae, Domibacillaceae, Falsibacillaceae, Heyndrickxiaceae, Lottiidibacillaceae, Oxalophagaceae, Pradoshiaceae, Rossellomoreaceae, Schinkiaceae, Sulfoacidibacillaceae and Sutcliffiellaceae. This work represents a genomic sequence-based and systematic framework for classifying the order Caryophanales at the family level, providing new insights into its evolution.

Bacillales: From Taxonomy to Biotechnological and Industrial Perspectives

For a long time, the genus Bacillus has been known and considered among the most applicable genera in several fields. Recent taxonomical developments resulted in the identification of more species in Bacillus-related genera, particularly in the order Bacillales (earlier heterotypic synonym: Caryophanales), with potential application for biotechnological and industrial purposes such as biofuels, bioactive agents, biopolymers, and enzymes. Therefore, a thorough understanding of the taxonomy, growth requirements and physiology, genomics, and metabolic pathways in the highly diverse bacterial order, Bacillales, will facilitate a more robust designing and sustainable production of strain lines relevant to a circular economy. This paper is focused principally on less-known genera and their potential in the order Bacillales for promising applications in the industry and addresses the taxonomical complexities of this order. Moreover, it emphasizes the biotechnological usage of some engineered strains of the order Bacillales. The elucidation of novel taxa, their metabolic pathways, and growth conditions would make it possible to drive industrial processes toward an upgraded functionality based on the microbial nature.

Litoribacterium kuwaitense gen. nov., sp. nov., isolated from a Kuwait tidal flat

A Gram-stain-positive, strictly aerobic, spore-forming, rod-shaped and non-motile bacterium designated strain SIJ1^T was obtained from tidal flat sediment collected from the northern shore of Kuwait Bay, northwest of the Arabian Gulf. Strain SIJ1^T grew optimally at 30 °C and pH 7–8 in the presence of 6 % (w/v) NaCl. The cell-wall peptidoglycan was based on meso-diaminopimelic acid and an unsaturated menaquinone with seven isoprene units (MK-7) was the predominant respiratory quinone. It contained anteiso-C_15 : 0, iso-C_16 : 0 and iso-C_15 : 0 as the major fatty acids and ribose as the major whole-cell sugar. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipid, an unidentified glycolipid, phosphoglycolipid and an unidentified lipid. Phylogenetic analysis based on 16S rRNA genes revealed that SIJ1^T showed a distinct evolutionary lineage within the Firmicutes. The DNA G+C content was 43.1 mol% and the full genome analysis for strain SIJ1^T showed that it had a genome size of 3 989 945 bp and contained 4085 predicted protein-encoding genes. The SIJ1^T annotated genome showed more stress resistance encoding genes in comparison to its closely related strains. The amino acid identity and average nucleotide identity data for the whole genome proved that strain SIJ1^T does indeed represent a novel genus. The strain was distinguishable from the phylogenetically related genera through differences in several phenotypic properties. On the basis of the phenotypic, phylogenetic and genetic data, strain SIJ1^T represents a novel genus and species in the family Bacillaceae, for which the name Litoribacterium kuwaitense gen. nov., sp. nov. is proposed. The type strain is SIJ1^T (=DSM 28862^T=LMG 28316^T).

Radiobacillus deserti gen. nov., sp. nov., a UV-resistant bacterium isolated from desert soil

A Gram-stain-positive, aerobic, rod-shaped, non-motile, endospore-forming and UV-resistant bacterial strain, designated strain TKL69^T, was isolated from sandy soil sampled in the Taklimakan Desert. The strain grew at 20-50 °C, pH 6-9 and with 0-12 % (w/v) NaCl. The major fatty acids were anteiso-C_15 : 0, iso-C_15 : 0 and C_16 : 0. The only respiratory quinone was MK-7. The cell-wall peptidoglycan was meso-diaminopimelic acid. Diphosphatidyl glycerol, two unidentified aminophospholipids and one unidentified phospholipid were identified as the major polar lipids. Genomic DNA analysis revealed a G+C content of 38.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain TKL69^T has the highest similarity to Salinibacillus xinjiangensis CGMCC 1.12331^T (96.9 %) but belongs to an independent taxon separated from other genera of the family Bacillaceae. Phylogenetic, phenotypic and chemotaxonomic analyses suggested that strain TKL69^T represents a novel species of a new genus, for which the name Radiobacillus gen. nov., sp. nov. is proposed, with the type strain being Radiobacillus deserti TKL69^T (=JCM 33497^T=CICC 24779^T).