Bacillus cellulasensis sp. nov., isolated from marine sediment

Isolation and identification of antifungal, antibacterial and nematocide agents from marine bacillus gottheilii MSB1

Pathogenic fungi employ numerous strategies to colonize plants, infect them, reduce crop yield and quality, and cause significant losses in agricultural production. The increasing use of chemical pesticides has led to various ecological and environmental issues, including the emergence of resistant weeds, soil compaction, and water pollution, all negatively impacting agricultural sustainability. Additionally, the extensive development of synthetic fungicides has adverse effects on animal and human health, prompting the exploration of alternative approaches and green strategies for phytopathogen control. Microorganisms living in sponges represent a promising source of novel bioactive secondary metabolites, potentially useful in developing new nematicidal and antimicrobial agents. This study focuses on extracting bioactive compounds from endosymbiotic bacteria associated with the marine sponge Hyrtios erect sp. (collected from NIOF Station, Hurghada, Red Sea, Egypt) using various organic solvents. Bacillus sp. was isolated and identified through 16 S rRNA gene sequencing. The biocidal activity of Bacillus gotheilii MSB1 extracts was screened against plant pathogenic bacteria, fungi, and nematodes. The n-butanol extract showed significant potential as a biological fungicide against Alternaria alternata and Fusarium oxysporum. Both n-hexane and ethyl acetate extracts exhibited negative impacts against the plant pathogenic bacteria Erwinia carotovora and Ralstonia solanacearum, whereas the n-butanol extract had a positive effect. Regarding nematicidal activity, ethyl acetate and n-butanol extracts demonstrated in-vitro activity against the root-knot nematode Meloidogyne incognita, which causes serious vegetable crop diseases, but the n-hexane extract showed no positive effects. The findings suggest that bioactive compounds from endosymbiotic bacteria associated with marine sponges, particularly B. gotheilii MSB1, hold significant potential as alternative biological control agents against plant pathogens. The n-butanol extract, in particular, displayed promising biocidal activities against various plant pathogenic fungi, bacteria, and nematodes. These results support further exploration and development of such bioactive compounds as sustainable, environmentally friendly alternatives to synthetic pesticides and fungicides in agricultural practices.

Secondary Metabolites from Marine-Derived Bacillus: A Comprehensive Review of Origins, Structures, and Bioactivities

The marine is a highly complex ecosystem including various microorganisms. Bacillus species is a predominant microbialflora widely distributed in marine ecosystems. This review aims to provide a systematic summary of the newly reported metabolites produced by marine-derived Bacillus species over recent years covering the literature from 2014 to 2021. It describes the structural diversity and biological activities of the reported compounds. Herein, a total of 87 newly reported metabolites are included in this article, among which 49 compounds originated from marine sediments, indicating that marine sediments are majority sources of productive strains of Bacillus species Therefore, marine-derived Bacillus species are a potentially promising source for the discovery of new metabolites.

Phylogeny of the Bacillus altitudinis Complex and Characterization of a Newly Isolated Strain with Antilisterial Activity

ABSTRACT

Bacillus strain UTK D1-0055 was isolated from a laboratory environment and appeared to have antilisterial activity. The genome was sequenced, the strain was identified as Bacillus altitudinis, and a high-quality complete annotated genome was produced. The taxonomy was evaluated for this and related Bacillus species (B. aerophilus, B. pumilus, B. safensis, B. stratosphericus, and B. xiamenensis) because the taxonomy is unclear and contains errors in public databases such as NCBI. The included strains grouped into seven clusters based on average nucleotide identity. Strains designated as B. aerophilus, B. altitudinis, and B. stratosphericus grouped together in the cluster containing the B. altitudinis type strain, suggesting that these three species should be considered a single species, B. altitudinis. The antimicrobial activity of UTK D1-0055 was evaluated against a panel of 15 Listeria strains (nine Listeria monocytogenes serotypes, Listeria innocua, and Listeria marthii), other foodborne pathogens (six Salmonella enterica serotypes and Escherichia coli), and three representative fungi (Saccharomyces cerevisiae, Botrytis cinerea, and Hyperdermium pulvinatum). Antibacterial activity was observed against all Listeria strains, but no antibacterial effects were found against the other tested bacterial and fungal strains. Biosynthetic gene clusters were identified in silico that may be related to the observed antibacterial activity, and these clusters included genes that putatively encode bacteriocins and nonribosomally synthesized peptides. The B. altitudinis strain identified in this investigation had a broad range of antilisterial activity, suggesting that it and other related strains may be useful for biocontrol in the food industry.

HIGHLIGHTS

Bacillus aerolatus sp. nov., a novel member of the genus Bacillus, isolated from bioaerosols in a school playground

A Gram-positive, endospore-forming, rod-shaped bacterium with a single flagellum, and a motile strain, designated CX253, was isolated from bioaerosols. The isolate is facultatively anaerobic, is able to grow at 25-45 ℃ (optimum 37 ℃) and pH 6.5-10.0 (optimum 7.5), and can tolerate up to 5.0% NaCl (w/v) under aerobic conditions. The diagnostic diamino acid in the cell wall of strain CX253^T is meso-diaminopimelic acid, while major isoprenoid quinone is menaquinone 6 (MK-6) along with a smaller amount of MK-7 (20%). The polar lipid profile is composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids and glycolipids. The major cellular fatty acid is iso-C_15:0 and anteiso-C_15:0. Phylogenetic analysis based on 16S rRNA gene and genome sequence grouped strain CX253^T into the genus Bacillus. The strain was most closely related to Bacillus thermotolerans CCTCC AB 2012108 ^T by comparison of 16S rRNA gene sequence (97.2% similarity) and to Bacillus wudalianchiensis CCTCC AB 2015266 ^T by comparison of gyrB gene sequence (80.1% similarity). The draft genome of strain CX253^T comprised 3,929,195 bp with a G + C content of 43.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain CX253^T and phylogenetically related Bacillus species were lower than 95% and 70%, respectively. Thus, the polyphasic evidence generated through phenotypic, chemotaxonomic and genomic methods confirmed that strain CX253^T (= GDMCC 1.1608 ^T = KACC 21318 ^T) was a novel species of the genus Bacillus, for which the name Bacillus aerolatus sp. nov. is proposed.

Genomic insights into the phylogeny of Bacillus strains and elucidation of their secondary metabolic potential

The genus Bacillus constitutes a plethora of species that have medical, environmental, and industrial applications. While genus Bacillus has been the focus of several studies where genomic data have been used to resolve many taxonomic issues, there still exist several ambiguities. Through the use of in-silico genome-based methods, we tried to resolve the taxonomic anomalies of a large set of Bacillus genomes (n = 178). We also proposed species names for uncharacterized strains and reported genome sequence of a novel isolate Bacillus sp. RL. In the hierarchical clustering on genome-to-genome distances, we observed 11 distinct monophyletic clusters and investigated the functional pathways annotated as the property of these clusters and core-gene content of the entire dataset. Thus, we were able to assert the possible outlier strains (n = 17) for this genus. Analyses of secondary metabolite potential of each strain helped us unravel still unexplored diversity for various biosynthetic genes.

Comparative genomics study reveals Red Sea Bacillus with characteristics associated with potential microbial cell factories (MCFs)

Recent advancements in the use of microbial cells for scalable production of industrial enzymes encourage exploring new environments for efficient microbial cell factories (MCFs). Here, through a comparison study, ten newly sequenced Bacillus species, isolated from the Rabigh Harbor Lagoon on the Red Sea shoreline, were evaluated for their potential use as MCFs. Phylogenetic analysis of 40 representative genomes with phylogenetic relevance, including the ten Red Sea species, showed that the Red Sea species come from several colonization events and are not the result of a single colonization followed by speciation. Moreover, clustering reactions in reconstruct metabolic networks of these Bacillus species revealed that three metabolic clades do not fit the phylogenetic tree, a sign of convergent evolution of the metabolism of these species in response to special environmental adaptation. We further showed Red Sea strains Bacillus paralicheniformis (Bac48) and B. halosaccharovorans (Bac94) had twice as much secreted proteins than the model strain B. subtilis 168. Also, Bac94 was enriched with genes associated with the Tat and Sec protein secretion system and Bac48 has a hybrid PKS/NRPS cluster that is part of a horizontally transferred genomic region. These properties collectively hint towards the potential use of Red Sea Bacillus as efficient protein secreting microbial hosts, and that this characteristic of these strains may be a consequence of the unique ecological features of the isolation environment.

Bacillus iocasae sp. nov., isolated from Pacmanus hydrothermal field, Manus Basin

A novel bacterial strain S36T was isolated from the deep-sea sediment collected from Pacmanus hydrothermal field, Manus Basin. The strain was Gram-stain-positive, aerobic, rod-shaped, endospore-forming, and motile. It was able to grow at 16-50 °C, pH 6.0-10.0, and in the presence of 0-11 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain S36T was a member of genus Bacillus and shares the highest sequence identity with Bacillus herbersteinensis D-1,5aT (97.0 %). The value of DNA-DNA hybridization between strain S36T and B. herbersteinensis D-1,5aT was 22.8 %. The cell wall diagnostic diamino acid of strain S36T was meso-diaminopimelic acid and the polar lipid profile of strain S36T contained diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The predominant respiratory quinine was MK-7. The major cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The genomic DNA G+C content of strain S36T was 43.0 mol%. On the basis of phylogenetic analysis, DNA-DNA hybridization, and phenotypic characteristics, it was concluded that strain S36T represents a novel species of the genus Bacillus, for which the name Bacillus iocasae sp. nov. was proposed. The type strain is S36T (=KCTC 33864T=DSM 104297T=CGMCC 1.16030T).