Cellulolytic potential of mangrove bacteria Bacillus haynesii DS7010 and the effect of anthropogenic and environmental stressors on bacterial survivability and cellulose metabolism

Cellulose degrading bacterial diversity of Bhitarkanika mangrove ecosystem, India, was uncovered and the cellulose degradation mechanism in Bacillus haynesii DS7010 under the modifiers such as pH (pCO2), salinity and lead (Pb) was elucidated in the present study. The abundance of cellulose degrading heterotrophic bacteria was found to be higher in mangrove sediment than in water. The most potential strain, B. haynesii DS7010 showed the presence of endoglucanase, exoglucanase and β-glucosidase with the maximum degradation recorded at 48 h of incubation, with 1% substrate concentration at 41 °C incubation temperature. Two glycoside hydrolase genes, celA and celB were confirmed in this bacterium. 3D structure prediction of the translated CelA and CelB proteins showed maximum similarities with glycoside hydrolase 48 (GH48) and glycoside hydrolase 5 (GH5) respectively. Native PAGE followed by zymogram assay unveiled the presence of eight isoforms of cellulase ranged from 78 kDa to 245 kDa. Among the stressors, most adverse effect was observed under Pb stress at 1400 ppm concentration, followed by pH at pH 4. This was indicated by prolonged lag phase growth, higher reactive oxygen species (ROS) production, lower enzyme activity and downregulation of celA and celB gene expressions. Salinity augmented bacterial metabolism up to 3% NaCl concentration. Mangrove leaf litter degradation by B. haynesii DS7010 indicated a substantial reduction in cellulolytic potential of the bacterium in response to the synergistic effect of the stressors. Microcosm set up with the stressors exhibited 0.97% decrease in total carbon (C%) and 0.02% increase in total nitrogen (N%) after 35 d of degradation while under natural conditions, the reduction in C and the increase in N were 4.05% and 0.2%, respectively. The findings of the study suggest the cellulose degradation mechanism of a mangrove bacterium and its resilience to the future consequences of environmental pollution and climate change.

Culture-dependent and -independent analyses of bacterial compositions and its contributions to formation of γ-aminobutyric acid and poly-γ-glutamic acid in Cheonggukjang

This study was performed to unveil bacterial compositions and their contributions to the formation of γ-aminobutyric acid (GABA) and poly-γ-glutamic acid (γ-PGA) in Cheonggukjang. To predict possible key factors contributing to the content of the bioactive compounds in Cheonggukjang, commercial products were analyzed for various parameters. The content of GABA and γ-PGA showed a negative (R2 = 0.61 - 0.73) and positive correlation (R2 = 0.53 - 0.96) with antioxidative activity. Consistently, GABA content showed a moderate negative correlation with γ-PGA content (R2 = 0.58). Among the physicochemical and microbial parameters, only salinity showed a moderate negative correlation with γ-PGA content (R2 = 0.75), which might be due to the inhibition of bacterial growth. It was also suggested that multiple factors (including bacterial species) were involved in the formation of GABA and γ-PGA in Cheonggukjang. To reveal dominant bacterial species and further presume their contributions to the bioactive compound formation in Cheonggukjang, both culture-independent (metagenomic) and -dependent (culturomic) methods were used. Culture-independent method showed that Bacillus piscis was dominant (23.37 - 94.89 %), followed by B. hisashii (0.00 - 62.45 %) and B. coagulans (0.00 - 13.82 %). Considering the quantitative speciation data on the bioactive compound content in Cheonggukjang (and bacterial production capability) together, it was further elucidated that B. piscis contributed primarily to the bioactive compound formation. Unlike this, culture-dependent analysis revealed that B. licheniformis and B. subtilis were dominant (30.0 - 47.6 and 17.5 - 39.5 %, respectively). Based on the quantitative speciation data on the bacterial production capability of GABA and γ-PGA, B. subtilis was the primarily contributing bacterial species to the bioactive compound formation. Consequently, it was observed that the bacterial compositions and their contributions to the bioactive compound formation determined by the two methods differed considerably, i.e., B. piscis and B. subtilis were identified to be prominent bacterial contributors, respectively, depending on the method used.

Natural chalcopyrite mitigates nitrous oxide emissions in sediment from coastal wetlands

Coastal wetlands are one of the most important natural sources of nitrous oxide (N2O). Previous studies have shown that copper-containing chemicals are able to reduce N2O emissions from these ecosystems. However, these chemicals may harm organisms present in coastal waters and sediment, and disturb the ecological balance of these areas. Here, we first investigated the physiological characteristics and genetic potential of denitrifying bacteria isolated from coastal wetlands. Based on an isolated denitrifier carrying a complete denitrification pathway, we tested the effect of the natural mineral chalcopyrite on N2O production by the bacteria. The results demonstrated that chalcopyrite addition lowers N2O emissions from the bacteria while increasing its N2 production rate. Among the four denitrification genes of the isolate, only nosZ gene expression was significantly upregulated following the addition of 2 mg L-1 chalcopyrite. Furthermore, chalcopyrite was applied to coastal wetland sediments. The N2O flux was significantly reduced in 50-100 mg L-1 chalcopyrite-amended sets relative to the controls. Notably, the dissolved Cu concentration in chalcopyrite-amended sediment remained within the limit set by the National Sewage Treatment Discharge Standard. qPCR and metagenomic analysis revealed that the abundance of N2O-reducing bacteria with the nosZ or nirK + nosZ genotype increased significantly in the chalcopyrite-amended groups relative to the controls, suggesting their active involvement in the reduction of N2O emissions. Our findings offer valuable insights for the use of natural chalcopyrite in large-scale field applications to reduce N2O emissions.

Similarities and differences of nano-sized levan synthesized by Bacillus haynesii at low and high temperatures: Characterization and bioactivity

Levan is a biopolymer with many different uses. Temperature is an important parameter in biopolymer synthesis. Herein, levan production was carried out from Bacillus haynesii, a thermophilic microorganism, in the temperature range of 4 °C-95 °C. The highest levan production was measured as 10.9 g/L at 37 °C. The synthesized samples were characterized by FTIR and NMR analysis. The particle size of the levan samples varied between 153 and 824.4 nm at different temperatures. In levan samples produced at high temperatures, the water absorption capacity is higher in accordance with the particle size. Irregularities were observed in the surface pores at temperatures of 60 °C and above. The highest emulsion capacity of 83.4 % was measured in the sample synthesized at 4 °C. The antioxidant activity of all levan samples synthesized at different temperatures was measured as 84 % on average. All synthesized levan samples showed antibacterial effect on pathogenic bacteria. In addition, levan synthesized at 45 °C showed the highest antimicrobial effect on E. coli ATCC 35218 with an inhibition zone of 21.3 ± 1.82 mm. Antimicrobial activity against yeast sample C. albicans, was measured only in levan samples synthesized at 80 °C, 90 °C, 95 °C temperatures. Levan synthesized from Bacillus haynesii at low and high temperatures showed differences in characterization and bioactivity.

Bacillus changyiensis sp. nov., isolated from coastal sediment

Two Gram-stain-positive, facultatively anaerobic, motile, endospore-forming, rod-shaped bacteria, designated CLL-3-40T and CLL-7-23, were isolated from coastal sediment sampled in Changyi, Shandong Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains were related to the genus Bacillus and close to six type strains of species within the Bacillus licheniformis group. In phenotypic characterization tests, strain CLL-3-40T could grow at 15-50 °C (optimum, 37 °C) and in media with pH 5-9 (optimum pH 7.0), and tolerate up to 12 % (w/v) NaCl. The fermentation broth supernatant extracted by ethyl acetate of strain CLL-3-40T could inhibit aquaculture pathogenic vibrios. The predominant cellular fatty acids of strain CLL-3-40T were anteiso-C15 : 0 (30.7 %) and iso-C15 : 0 (31.5 %); the peptidoglycan from cell-wall contained meso-diaminopimelic acid; the predominant quinone was menaquinone 7; and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, an unidentified glycolipid and two unidentified phospholipids. The digital DNA-DNA hybridization values and average nucleotide identities among strains CLL-3-40T and CLL-7-23 and their close type strains were less than 21.9 and 48.4 %, respectively, thereby indicating that strain CLL-3-40T should represent a novel species of the genus Bacillus. The genomic DNA G+C contents were 38.4 mol% in strain CLL-3-40T and 38.3 mol% in strain CLL-7-23. The 12 biosynthetic gene clusters of strain CLL-3-40T were predicted based on results from the online server antiSMASH. Based upon the consensus of phenotypic and genotypic results, strain CLL-3-40T should be classified as representing a novel species of the genus Bacillus, for which the name Bacillus changyiensis sp. nov. is proposed. The type strain is CLL-3-40T (= MCCC 1A14857T=JCM 35755T).

Bacillus Swezeyi B2 Strain: A Novel Alkaliphilic Bacterium Producer of Alkaline-, Thermal, Oxidant-, and Surfactant-Stable Protease, Extremely Efficient in Detergency

Proteolytic enzymes that are currently used to meet industrial demand are usually derived from Bacillus species. They find multiple technical applications, particularly they have been increasingly used as a key bio-additive in detergents. In this study, a novel alkalophilic bacterium was isolated from contaminated soil, exhibiting 1400 U/ml proteolytic activity, and identified as Bacillus swezeyi B2. The crude enzyme likely contained a single extracellular protease. This enzyme revealed optimum activity at pH 10 and 70 °C and was highly alkaline thermostable (7-12.5) and up to 70 °C. The protease activity was completely inhibited by Phenylmethylsulfonyl fluoride (PMSF) suggesting that it belongs to the serine protease group. It was highly stable in the presence of the strong anionic surfactant (SDS) and oxidizing agents (H₂O₂). The supernatant was lyophilized and showed high storage stability retaining 100% of its original activity after one year of conservation at 4 °C. The lyophilized product was evaluated for its detergent efficacy, it revealed excellent compatibility with various laundry detergents keeping its full original activity after incubation for 1 h with seven solid and liquid commercial detergents and it effectively removed chocolate stains at low washing temperature (40 °C) and low supplementation level (125 U/ml). The features of this single alkaline and thermotolerant protease, stable toward surfactants, oxidizing agents, and commercial detergents with stain removal efficacy support its ideal choice for supplementation in detergent formulations.

Suppression of Streptococcosis and Modulation of the Gut Bacteriome in Nile Tilapia (Oreochromis niloticus) by the Marine Sediment Bacteria Bacillus haynesii and Advenella mimigardefordensis

Streptococcosis is one of the major threats to Nile tilapia (Oreochromis niloticus) in most regions of the world. Recently, Enterococcus faecalis has been widely reported to be involved in streptococcosis in O. niloticus in Asia and Africa. This study aimed to isolate beneficial marine bacteria to evaluate their effects on growth, hematological parameters, nonspecific immunity, the gut bacteriome, and streptococcosis prevention efficacy in O. niloticus. A total of 36 marine soil bacteria were isolated, and in vitro screening was conducted to determine their antibacterial activities against fish pathogens. Two antagonistic bacteria were identified based on 16S rRNA gene sequencing, Bacillus haynesii CD223 and Advenella mimigardefordensis SM421. These bacteria were incorporated into fish feed and fed to O. niloticus for 90 days. The application of these strains via incorporation into fish feed significantly promoted growth, improved hematological parameters and immunoglobulin M (IgM) levels, modulated the gut bacteriome by reducing the load of pathogenic Enterococcus spp., and developed disease prevention efficacy in O. niloticus. Furthermore, in vivo assays revealed that the inclusion of extracellular products (ECPs) (at 250 μg mL-1) of CD223 and SM421 with feed significantly enhanced the rate of survival (100%) of O. niloticus from streptococcosis compared to the controls (only 30%). The ECPs of these bacteria also prevented 90 to 100% of fish from developing streptococcosis. These strains could be promising for safe use in O. niloticus farming to prevent and control the emergence of streptococcosis caused by E. faecalis. IMPORTANCE Nile tilapia (Oreochromis niloticus) is one of the most economically important cultured fish species throughout the world. Streptococcosis is a significant threat to global Nile tilapia farming. Enterococcus faecalis has recently emerged as an important pathogen of streptococcosis in Asia and Africa. The application of antibiotics and probiotics and vaccination are the major ways to combat streptococcosis. However, the extensive use of antibiotics leads to the development of antibiotic resistance in pathogenic as well as environmental bacteria, which is a great threat to public health. There is no study on preventing streptococcosis caused by E. faecalis using beneficial bacteria. For the first time, the present study demonstrated that two marine bacteria, Bacillus haynesii strain CD223 and Advenella mimigardefordensis strain SM421, have great potential for controlling streptococcosis in Nile tilapia. These bacteria also enhanced the growth, improved hematological parameters and IgM levels, and positively modulated the gut bacteriome of Nile tilapia.

Great Abilities of Shinella zoogloeoides Strain from a Landfarming Soil for Crude Oil Degradation and a Synergy Model for Alginate-Bead-Entrapped Consortium Efficiency

Oil contamination is of great concern worldwide and needs to be properly addressed. The present work aimed to contribute to the development of bacterial consortia for oil recovery. We investigated the community structure of a landfarming-treated soil (LF2) by metagenomics to unravel the presence of hydrocarbon degraders. Moreover, we isolated Shinella zoogloeoides LFG9 and Bacillus swezeyi LFS15 from LF2 and combined them with Pseudomonas guguanensis SGPP2 isolated from an auto mechanic workshop soil to form the mixed consortium COG1. Bacterial isolates were tested for biosurfactant production. Additionally, the bioremediation potential of COG1 was studied as free and entrapped consortia by gas chromatography-mass spectrometry, in comparison to the single strains. Results revealed the presence of Actinobacteria (66.11%), Proteobacteria (32.21%), Gammaproteobacteria (5.39%), Actinomycetales (65.15%), Burkholderiales (13.92%), and Mycobacterium (32.22%) taxa, indicating the presence of hydrocarbon degraders in soil LF2. All three isolated strains were biosurfactant producers capable of degrading crude oil components within 14 days. However, Shinella zoogloeoides LFG9 performed best and was retained as candidate for further bioremediation investigation. In addition, COG1 performed better when immobilized, with entrapment effectiveness manifested by increased fatty acids and aromatic compound degradation. Attempt to improve crude oil biodegradation by adding surfactants failed as sodium dodecyl sulfate restrained the immobilized consortium performance.

Optimization and Characterization of a Novel Exopolysaccharide from Bacillus haynesii CamB6 for Food Applications

Extremophilic microorganisms often produce novel bioactive compounds to survive under harsh environmental conditions. Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, are functional biopolymers that act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermophilic Bacillus haynesii CamB6 from a slightly acidic (pH 5.82) Campanario hot spring (56.4 °C) located in the Central Andean Mountains of Chile. Physicochemical properties of the EPS were characterized by different techniques: Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D and 2D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps. GPC and HPLC analysis showed that the EPS is a low molecular weight heteropolymer composed of mannose (66%), glucose (20%), and galactose (14%). FTIR analysis demonstrated the polysaccharide nature (-OH groups, Acetyl groups, and pyranosic ring structure) and the presence of different glycosidic linkages among sugar residues, which was further confirmed by NMR spectroscopic analyses. Moreover, D-mannose α-(1→2) and α-(1→4) linkages prevail in the CamB6 EPS structure. TGA revealed the high thermal stability (240 °C) of the polysaccharide. The functional properties of the EPS were evaluated for food industry applications, specifically as an antioxidant and for its emulsification, water-holding (WHC), oil-holding (OHC), and flocculation capacities. The results suggest that the study EPS can be a useful additive for the food-processing industry.

Agrobacterium cavarae sp. nov., isolated from maize (Zea mays L.) roots

A bacterial strain designated as RZME10^T was isolated from a Zea mays L. root collected in Spain. Results of analysis of the 16S rRNA gene sequence showed that this strain belongs to the genus Agrobacterium with Agrobacterium larrymoorei ATCC 51759^T being the most closely related species with 99.9 % sequence similarity. The similarity values of the rpoB, recA, gyrB, atpD and glnII genes between strain RZME10^T and A. larrymoorei ATCC 51759^T were 93.5, 90.0, 88.7, 87.9 and 90.1 %, respectively. The estimated average nucleotide identity using blast and digital DNA-DNA hybridization values between these two strains were 80.4 and 30.2 %, respectively. The major fatty acids of strain RZME10^T are those from summed feature 8 (C_18 : 1 ω6c/C_18 : 1 ω7c) and C_16 : 0. Pathogenicity tests on tomato and carrot roots showed that strain RZME10^T was not able to induce plant tumours. Based on the results of genomic, chemotaxonomic and phenotypic analyses, we propose that strain RZME10^T represents a novel species named Agrobacterium cavarae sp. nov. (type strain RZME10^T=CECT 9795^T=LMG 31257^T).

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.

Bacillus pasinlerensis sp. nov., a thermophilic bacterium isolated from a hot spring in Turkey

A Gram-reaction-positive, endospore-forming bacterium, designated strain P1^T, was isolated from water samples collected from Pasinler Hot Spring and characterized using a polyphasic approach to clarify its taxonomic position. Strain P1^T was found to have chemotaxonomic and morphological characteristics consistent with its classification in the genus Bacillus. The strain shared the highest 16S rRNA gene sequence identity values with Bacillus thermolactis R-6488^T (97.6 %) and Bacillus kokeshiiformis MO-04^T (97.2 %) and formed a distinct clade with both type strains in the phylogenetic trees based on 16S rRNA gene sequences. Strain P1^T could grow optimally at 55 °C and in the presence of 2 % NaCl. The organism was found to contain meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The predominant menaquinone was determined to be MK-7. The major cellular fatty acids were identified as iso-C_15 : 0, iso-C_17 : 0 and anteiso-C_17 : 0. Based upon the consensus of phenotypic and phylogenetic analyses, strain P1^T represents a novel species of the genus Bacillus, for which the name Bacillus pasinlerensis sp. nov. is proposed. The type strain is P1^T (=DSM 107529^T=CECT 9885^T=NCCB 100674^T).

High taxonomic diversity of Micromonospora strains isolated from Medicago sativa nodules in Western Spain and Australia

The genus Micromonospora has been found in nodules of several legumes and some new species of this genus were isolated from these plant organs. In this study we analysed the taxonomic diversity of Micromonospora strains isolated from alfalfa nodules in Spain and Australia on the basis of three phylogenetic markers, the rrs and gyrB genes and 16S-23S intergenic spacer (ITS). The genome analysis of selected strains representative of different clusters or lineages found after rrs, gyrB and ITS analyses confirmed the results obtained with these phylogenetic markers. They showed that the analysed strains belong to at least 18 Micromonospora species including previously described ones, such as Micromonospora noduli, Micromonospora ureilytica, Micromonospora taraxaci, Micromonospora zamorensis, Micromonospora aurantiaca and Micromonospora tulbaghiae. Most of these strains belong to undescribed species of Micromonospora showing the high taxonomic diversity of strains from this genus inhabiting alfalfa nodules. Although Micromonospora strains are not able to induce the formation of these nodules, and it seems that they do not contribute to fix atmospheric nitrogen, they could play a role related with the mechanisms of plant growth promotion and pathogen protection presented by Micromonospora strains isolated from legume nodules.

Promotion of Bacillus subtilis subsp. inaquosorum, Bacillus subtilis subsp. spizizenii and Bacillus subtilis subsp. stercoris to species status

Bacillus subtilis currently encompasses four subspecies, Bacillus subtilis subsp. subtilis, Bacillus subtilis subsp. inaquosorum, Bacillus subtilis subsp. spizizenii and Bacillus subtilis subsp. stercoris. Several studies based on genomic comparisons have suggested these subspecies should be promoted to species status. Previously, one of the main reasons for leaving them as subspecies was the lack of distinguishing phenotypes. In this study, we used comparative genomics to determine the genes unique to each subspecies and used these to lead us to the unique phenotypes. The results show that one difference among the subspecies is they produce different bioactive secondary metabolites. B. subtilis subsp. spizizenii is shown conserve the genes to produce mycosubtilin, bacillaene and 3,3'-neotrehalosadiamine. B. subtilis subsp. inaquosorum is shown conserve the genes to produce bacillomycin F, fengycin and an unknown PKS/NRPS cluster. B. subtilis subsp. stercoris is shown conserve the genes to produce fengycin and an unknown PKS/NRPS cluster. While B. subtilis subsp. subtilis is shown to conserve the genes to produce 3,3'-neotrehalosadiamine. In addition, we update the chemotaxonomy and phenotyping to support their promotion to species status.

Isolation and characterization of a novel thermophile; Bacillus haynesii, applied for the green synthesis of ZnO nanoparticles

The establishment of a benign system for the nanoparticle (NPs) synthesis, is a key in nanotechnology for the environmental and health care industries. Therefore, enrichment of novel biological systems for the green synthesis is in significant demand, to lift up these compounds in the biomedical industries. The present work, reports the green synthesis of ZnO NPs, employing a novel thermophile, identified as Bacillus haynesii (GeneBank: MG822851) isolated from the leaf of date palm plant (Phoenix dactylifera), as an eco-friendly nanobiofactory. Physiochemical characterization of ZnO NPs (50 ± 5 nm in size), was achieved by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), diffuse reflectance UV-Visible spectroscopy (DR UV-Vis spectroscopy), Thermogravimetry analysis (TGA), scanning electron microscopy (SEM) and transmissiom electron microscopy (TEM). The morphogenesis and antimicrobial activity of synthesized ZnO NPs, was studied by evaluating the minimum inhibitory/bactericidal concentration (MIC&MBC) against Escherchia coli (8 and 16 mg/mL) and Staphylococcus aureus (4 and 8 mg/mL), respectively. The present study encourages the use of B. haynesii for the green synthesis of ZnO NP. To the best of our knowledge, this is the first report on the study of thermophilic, B. haynesii for green synthesis of NPs in general and ZnO NPs in particular.

Iturinic Lipopeptide Diversity in the Bacillus subtilis Species Group - Important Antifungals for Plant Disease Biocontrol Applications

Iturins and closely related lipopeptides constitute a family of antifungal compounds known as iturinic lipopeptides that are produced by species in the Bacillus subtilis group. The compounds that comprise the family are: iturin, bacillomycin D, bacillomycin F, bacillomycin L, mycosubtilin, and mojavensin. These lipopeptides are prominent in many Bacillus strains that have been commercialized as biological control agents against fungal plant pathogens and as plant growth promoters. The compounds are cyclic heptapeptides with a variable length alkyl sidechain, which confers surface activity properties resulting in an affinity for fungal membranes. Above a certain concentration, enough molecules enter the fungal cell membrane to create a pore in the cell wall, which leads to loss of cell contents and cell death. This study identified 330 iturinic lipopeptide clusters in publicly available genomes from the B. subtilis species group. The clusters were subsequently assigned into distinguishable types on the basis of their unique amino acid sequences and then verified by HPLC MS/MS analysis. The results show some lipopeptides are only produced by one species, whereas certain others can produce up to three. In addition, four species previously not known to produce iturinic lipopeptides were identified. The distribution of these compounds among the B. subtilis group species suggests that they play an important role in their speciation and evolution.

Bacillus salacetis sp. nov., a slightly halophilic bacterium from Thai shrimp paste (Ka-pi)

A Gram-stain-positive, slightly halophilic, endospore-forming, strictly aerobic, rod-shaped bacterium, designated SKP7-4^T, was isolated from shrimp paste collected from Samut Sakhon province, Thailand. Strain SKP7-4^T grew at pH 6.0-9.0 (optimum, 7.5), at 20-40 °C (37 °C) and in 0-15 % (w/v) NaCl (1-3 %). The diamino acid found in the cell-wall peptidoglycan was meso-diaminopimelic acid. Menaquinone with seven isoprene units was the major isoprenoid quinone. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and three unidentified phospholipids were detected as polar lipids. It contained iso-C15 : 0 and anteiso-C15 : 0 as major cellular fatty acids. On the basis of 16S rRNA gene sequence analysis, strain SKP7-4^T belonged to the genus Bacillus and was closely related to Bacillus vietnamensis JCM 11124^T, Bacillus marisflavi JCM 11544^T, Bacillus aquimaris JCM 11545^T and Bacillusoryzaecorticis JCM 19602^T, with 98.7, 97.9, 97.8 and 97.8 % similarity, respectively. The draft genome of SKP7-4^T was 4.68 Mb with 5208 coding sequences with an average G+C content of 43.2 mol%. The ANIb and ANIm values of strain SKP7-4^T were 70.0 and 84.3 %, respectively, and the digital DNA-DNA hybridization value was 20 % in comparison with the draft genome of B. vietnamensis JCM 11124^T. On the basis of the results of phenotypic, chemotaxonomic and phylogenetic analyses, the strain should represent a novel species of the genus Bacillus and the name Bacillus salacetis sp. nov. is proposed. The type strain is SKP7-4^T (=JCM 33205^T=KCTC 43014^T=TISTR 2596^T).