Brevicillin, a novel lanthipeptide from the genus Brevibacillus with antimicrobial, antifungal, and antiviral activity.

AIM: This study was aimed to determine antimicrobial and antiviral activity of a novel lanthipeptide from a Brevibacillus sp. for disinfectant application. METHODS AND RESULTS: The antimicrobial peptide (AMP) was produced by a bacterial strain AF8 identified as a member of the genus Brevibacillus representing a novel species. Whole genome sequence analysis using BAGEL identified a putative complete biosynthetic gene cluster involved in lanthipeptide synthesis. The deduced amino acid sequence of lanthipeptide named as brevicillin, showed >30% similarity with epidermin. Mass determined by MALDI-MS and Q-TOF suggested posttranslational modifications like dehydration of all Ser and Thr amino acids to yield Dha and Dhb, respectively. Amino acid composition determined upon acid hydrolysis is in agreement with core peptide sequence deduced from the putative biosynthetic gene bvrAF8. Biochemical evidence along with stability features ascertained posttranslational modifications during formation of the core peptide. The peptide showed strong activity with 99% killing of pathogens at 12 µg ml-1 within 1 minute. Interestingly, it also showed potent anti-SARS-CoV-2 activity by inhibiting ∼99% virus growth at 10 µg ml-1 in cell culture-based assay. Brevicillin did not show dermal allergic reactions in BALB/c mice. CONCLUSION: This study provides detailed description of a novel lanthipeptide and demonstrates its effective antibacterial, antifungal and anti-SARS-CoV-2 activity.

Taxonomic and genomic characterization of Sporosarcina cyprini sp. nov., moderately tolerant of Cr+6 and Cd+2 isolated from the gut of invasive fish Cyprinus carpio var. communis (Linn., 1758).

A Gram-stain-positive, motile, and rod-shaped bacterium, designated as strain MB25T, was isolated from the gut of Cyprinus carpio from the highly polluted river Yamuna, India. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain MB25T belonged to the genus Sporosarcina, sharing the highest sequence similarity with S. luteola Y1T (98.98%) and S. koreensis S-K12T (98.91%). Digital DNA-DNA hybridization and average nucleotide identity values of strain MB25T with strain Y1T and S-K12T were 18.9, 77.69, and 18.2, 76.80 respectively. Genome analysis of strain MB25T revealed its biotechnological properties such as tolerance to potent heavy metals, genes for the production of carbohydrate-active enzymes, antimicrobial compounds, and also degradation of aromatic compounds. The G + C content of strain MB25T genome was 45%. Growth observed at 10-40 °C (optimum, 28-30 °C), pH 6.0-8.5 (optimum pH 7.5-8.0); NaCl concentrations up to 6.0% (w/v). The dominant respiratory quinone was MK-7, cell wall peptidoglycan is of the A-4 type containing amino acids Lys-Glu and the major fatty acids are anteiso-C11:0 and iso-C15: 0. The major polar lipids of strain MB25T are diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. On the basis of phenotypic, chemotaxonomic, phylogenetic, and phylogenomic data, strain MB25T represents a novel species of the genus Sporosarcina, for which the name Sporosarcina cyprini sp. nov. is proposed. The type strain is MB25T (= MCC 4366 T = JCM 34521 T = CCM 9113 T).

Lysobacter arvi sp. nov. Isolated from Farmland Soil.

A bacterial strain designated as UC was isolated from farmland soil. Strain UCT formed a pale yellow colony on nutrient agar. Cell morphology revealed it as the rod-shaped bacterium that stained Gram-negative. The 16S rRNA gene sequence analysis identified strain UCT as a member of the genus Lysobacter that showed high identity with L. soli DCY21T (99.5%), L. panacisoli CJ29T (98.7%), and L. tabacisoli C8-1T (97.9%). It formed a distinct cluster with these strains in the neighbor-joining phylogenetic tree. A similar tree topology was observed in TYGS-based phylogenomic analysis. However, genome sequence analyses of strain UCT showed 87.7% average nucleotide identity and 34.7% digital DNA-DNA hybridization similarity with the phylogenetically closest species, L. soli DCY21T. The similarity was much less with other closely related strains of the genus Lysobacter. The G + C content of strain UCT was 68.1%. Major cellular fatty acids observed were C14:0 iso (13.4%), C15:0 iso (13.6%), and C15:0 anteiso (14.8%). Quinone Q-8 was the major respiratory ubiquinone. Predominant polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol. Production of xanthomonadin pigment was observed. Based on phenotypic differences and phylogenomic analysis, strain UCT represents a novel species of the genus Lysobacter, for which the name Lysobacter arvi is proposed. The type strain of the novel species is UCT (= KCTC 92613T = JCM 23757T = MTCC 12824T).

Evaluation of Human Dental Plaque Lactic Acid Bacilli for Probiotic Potential and Functional Analysis in Relevance to Oral Health.

Members of the lactic acid bacillus group are well-known probiotics and primarily isolated from fermented food, dairy products, intestinal and gut environment of human. Since probiotics from the human source are preferred, there exists a huge repertoire of lactobacilli in the human oral cavity which could prove a much better niche to be exploited for these beneficial microorganisms. Therefore, in this study, four lactobacilli strains, including strain DISK7, reported earlier, isolated from dental plaque samples of a healthy humans were evaluated for their probiotic potential. Strains displayed 99.9% of 16S rRNA gene sequence identity with species of the genera Lactobacillus and Limosilactobacillus. All strains showed lactic acid production, tolerance to low pH and antibiotic sensitivity. Variations were observed among strains in their aggregation ability, biofilm formation, bile salt resistance and cholesterol degradation. Further, we analyzed the interaction of strains with other oral commensals and opportunistic pathogens in co-culture experiments. Isolates DISK7 and DISK26 exhibited high co-aggregation (> 70%) with secondary colonizers, Streptococcus pyogenes and Veillonella parvula, respectively, but their aggregation ability was decreased with opportunistic pathogens. Furthermore, strains showed a substantial increase in biofilm in co-culture with other Lactobacillus isolates, indicating their ability to proliferate commensal bacteria in the oral environment. These microbes continually evolve in terms of niche adaptation as evidenced in genome analysis. The highlight of the investigation is the isolation and evaluation of the probiotic lactobacilli from the human oral cavity, which could prove a much better niche to be exploited for the effective commercialization of these beneficial microbes. Taken together, probiotic properties and interaction with commensal bacteria, these isolates exhibit the huge potential to be developed as alternative bioresource agents for maintenance of oral health. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01108-2.

Pedobacter fastidiosus sp. nov., isolated from glacial habitats of maritime Antarctica.

Strains P8930T and 478 were isolated from Antarctic glaciers located on James Ross Island and King George Island, respectively. They comprised Gram-stain-negative short rod-shaped cells forming pink pigmented colonies and exhibited identical 16S rRNA gene sequences and highly similar MALDI TOF mass spectra, and hence were assigned as representatives of the same species. Phylogenetic analysis based on 16S rRNA gene sequences assigned both isolates to the genus Pedobacter and showed Pedobacter frigidisoli and Pedobacter terrae to be their closest phylogenetic neighbours, with 97.4 and 97.2 % 16S rRNA gene sequence similarities, respectively. These low similarity values were below the threshold similarity value of 98.7%, confirming the delineation of a new bacterial species. Further genomic characterization included whole-genome sequencing accompanied by average nucleotide identity (ANI) and digital DNA-DNA hybridization calculations, and characterization of the genome features. The ANI values between P8930T and P. frigidisoli RP-3-11T and P. terrae DSM 17933T were 79.7 and 77.6 %, respectively, and the value between P. frigidisoli RP-3-11T and P. terrae DSM 17933T was 77.7 %, clearly demonstrating the phylogenetic distance and the novelty of strain P8930T. Further characterization included analysis of cellular fatty acids, quinones and polar lipids, and comprehensive biotyping. All the obtained results proved the separation of strains P8930T and 478 from the other validly named Pedobacter species, and confirmed that they represent a new species for which the name Pedobacter fastidiosus sp. nov. is proposed. The type strain is P8930T (=CCM 8938T=LMG 32098T).

A comparative study of in-vitro and in-silico anti-candidal activity and GC-MS profiles of snow mountain garlic vs. normal garlic.

AIM: The study aimed to profile the volatile phytocomposition of snow mountain garlic (SMG) compared to normal garlic and investigate the anti-Candida efficacy against clinically relevant multi-drug resistant isolates of Candida species. METHODS AND RESULTS: Herein, SMG has shown significantly superior fungicidal power at 2x-MIC dose against C. albicans and C. glabrata in killing kinetic evaluation unlike the fungistatic effect of normal garlic. GC-MS headspace-based profiling of SMG showed 5 unique volatile compounds and a 5-fold higher content of saponins than normal garlic. In an in-silico analysis, cholesta-4,6-dien-3-ol,(3-beta) was uniquely identified in SMG as a potential inhibitor with high binding affinity to the active site of exo-1,3-betaglucan synthase, an established anti-candida drug target crucial for the biofilm matrix formation, thus suggesting a plausible anti-Candida mechanism. CONCLUSION: The in-vitro and in-silico studies have demonstrated the Candida-cidal and anti-biofilm activities of SMG, distinguishing it from the Candida-static efficacy of normal garlic. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report that identifies several phytochemical signatures of SMG along with a potential anti-Candida compound, that is cholesta-4,6-dien-3-ol,(3-beta)-, which appears worthy of detailed studies in the future to explore the utility of SMG as a fungal phytotherapy agent, especially against drug-resistant Candida sp.

Lacrimispora defluvii PI-S10-B5AT sp. nov., an Obligate Anaerobe, Isolated from an Industrial Waste and Reclassification of Hungatella xylanolytica as Lacrimispora xylanolytica and Clostridium indicum as Lacrimispora indica Comb. nov.

A bacterial strain was isolated from the waste slurry of an industrial effluent treatment plant near Patancheru, Hyderabad, India, and designated as PI-S10-B5AT. It was an obligately anaerobic, spore-forming, rod-shaped, motile bacterium that stained Gram-positive. The strain revealed high 16S rRNA gene sequence identity with Hungatella xylanolytica DSM 3808T (99.4%) followed by members of the genus Lacrimispora (98.8-93.3%). However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization of genome sequence exhibited similarity in the range of 94.3-68.7% and 57.4-18.8%, respectively, with all closely related strains. A multi-gene phylogenetic analysis of strain PI-S10-B5AT was performed to investigate the taxonomic affiliation, which revealed formation of a coherent cluster with the members of the genus Lacrimispora. The DNA G + C content was 41.8 mol%. Major polar lipids were glyco- and phospholipids. The fatty acids analysis showed C16:0 to be the major fatty acid. The predominant respiratory quinone was menaquinone-7 (MK-7). Based on phenotypic, chemotaxonomic, and whole-genome phylogenetic analysis, strain PI-S10-B5AT is assigned as a novel species of the genus Lacrimispora, for which the name Lacrimispora defluvii is proposed. The type strain of the novel species is PI-S10-B5AT (= MTCC 12280T; = DSM 24980T) isolated from waste slurry of effluent treatment plant. The genomic analysis of type strains of C. indicum PI-S10-A1BT and H. xylanolytica DSM 3808T showed ANI and AAI values consistent with members of the genus Lacrimispora. Therefore, these strains are ascertained to the genus Lacrimispora and reclassified as Lacrimispora indica and Lacrimispora xylanolytica comb. nov.

Xanthomonas sontii sp. nov., a non-pathogenic bacterium isolated from healthy basmati rice (Oryza sativa) seeds from India.

We report three yellow-pigmented, Gram-negative, aerobic, rod-shaped, motile bacterial isolates designated as PPL1T, PPL2, and PPL3 from healthy basmati rice seeds. Phenotypic and 16S rRNA gene sequence analysis assigned these isolates to the genus Xanthomonas. The 16S rRNA showed a 99.59% similarity with X. sacchari CFBP 4641T, a sugarcane pathogen. Further, biochemical and fatty acid analysis revealed it to be closer to X. sacchari. Still, it differed from other species in general and known rice associated species such as X. oryzae (pathogenic) and X. maliensis (non-pathogenic) in particular. Interestingly, the isolatess in this study were isolated from healthy rice plants but are closely related to species that is pathogenic and isolated from diseased sugarcane. Accordingly, in planta studies revealed that PPL1T, PPL2, and PPL3 are non-pathogenic to rice plants upon leaf inoculation. Taxonogenomic studies based on orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) values with type strains of Xanthomonas species were below the recommended threshold values for species delineation. Whole genome-based phylogenomic analysis revealed that these isolates formed a distinct monophyletic clade with X. sacchari CFBP 4641T as their closest neighbour. Further, pangenome analysis revealed PPL1T, PPL2, and PPL3 isolates to comprise NRPS cluster along with a large number of unique genes associated with the novel species. Based on polyphasic and genomic approaches, a novel lineage and species associated with healthy rice seeds for which the name Xanthomonas sontii sp. nov. is proposed. The type strain for the X. sontii sp. nov. is PPL1T (JCM 33631T = CFBP 8688T = ICMP 23426T = MTCC 12491T) and PPL2 (JCM 33632 = CFBP 8689 = ICMP 23427 = MTCC 12492) and PPL3 (JCM 33633 = CFBP 8690 = ICMP 23428 = MTCC 12493) as other strains of the species.

Improvisation and Evaluation of Laterosporulin Coated Titanium Surfaces for dental Applications: An In Vitro Investigation.

Despite recent improvement in implant survival rates, there remains a significant demand for enhancing the long-term clinical efficacy of titanium (Ti) implants, particularly for the prevention of peri-implantitis. Bioactive substances such as antimicrobial peptides are emerging as effective alternatives for contemporary antimicrobial agents used in dental health care. Current research work was focused to use laterosporulins that are non-haemolytic cationic antimicrobial peptides from Brevibacillus spp. for coating commercially available Ti discs. The coated Ti surfaces were evaluated in vitro for biofilm formation by two dental plaque isolates Streptococcus gordonii strain DIGK25 and S. mutans strain DIGK119 as representatives of commensal and pathogenic streptococci respectively. The biofilm inhibition was ascertained with replicated experiments on hydroxyapatite discs and confirmed by florescence microscopy. The laterosporulin coated Ti discs showed significantly reduced biofilm formation by oral streptococci and displayed promising potential to enhance the antibacterial surface properties. Such improvised Ti surfaces may curb the menace of oral streptococcal biofilm formation on dental implants and the associated implant failures.

Salinicoccus cyprini sp. nov., isolated from the gut of mirror carp, Cyprinus carpio var. specularis.

A novel orange to pink coloured bacterial strain designated as CT19T was isolated from the gastrointestinal tract of mirror carp, Cyprinus carpio var. specularis (Lacepède, 1803) collected from the Gobind Sagar reservoir at village Lathiani, Una, Himachal Pradesh, India. Cells of the strain were found to be aerobic, Gram-stain-positive, non-motile and non-spore-forming coccoids. Based on the 16S rRNA gene sequence, the strain was closely related to Salinicoccus hispanicus J-82T (=DSM 5352T; 97.4 %), followed by S. sesuvii CC-SPL15-2T (=DSM 23267T; 96.4 %), S. amylolyticus JC304T (=KCTC 33661T; 95.6 %) and S. roseus DSM 5351T (95.4 %). Identity with all other members of the genus were <94.5 %. The draft genome of strain CT19T was assembled to 2.4 Mbp with a G+C content of 47.9 mol%. Average nucleotide identity and digital DNA-DNA hybridization values between strain CT19T and S. hispanicus J-82T were found to be 85.9 and 31.3% respectively which is far below the threshold for species delineation. Iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0, C16 : 0 and anteiso-C17 : 0 were the major cellular fatty acids of strain CT19T. Major polar lipids were diphosphatidylglycerol, phosphatidylgylcerol and an unidentified glycolipid. Respiratory quinone system was composed of menaquinone-6 and major cell wall amino acid was l-lysine. Based on phylogenomic, physiological and biochemical characteristics, strain CT19T represents a novel species of the genus Salinicoccus for which the name Salinicoccus cyprini sp. nov. is proposed. The type strain is CT19T (=KCTC 43022T =CCM 8886T=MCC 3834T).

Pseudomonas karstica sp. nov. and Pseudomonas spelaei sp. nov., isolated from calcite moonmilk deposits from caves.

A taxonomic study of two fluorescent Pseudomonas strains (HJ/4T and SJ/9/1T) isolated from calcite moonmilk samples obtained from two caves in the Moravian Karst in the Czech Republic was carried out. Results of initial 16S rRNA gene sequence analysis assigned both strains into the genus Pseudomonas and showed Pseudomonas yamanorum 8H1T as their closest neighbour with 99.8 and 99.7 % 16S rRNA gene similarities to strains HJ/4T and SJ/9/1T, respectively. Subsequent sequence analysis of rpoD, rpoB and gyrB housekeeping genes confirmed the highest similarity of both isolates to P. yamanorum 8H1T, but phylogeny and sequences similarities implied that they are representatives of two novel species within the genus Pseudomonas. Further study comprising whole-genome sequencing followed by average nucleotide identity and digital DNA-DNA hybridization calculations, repetitive sequence-based PCR fingerprinting with the REP and ERIC primers, automated ribotyping with the EcoRI restriction endonuclease, cellular fatty acid analysis, quinone and polar lipid characterization, and extensive biotyping confirmed clear separation of both analysed strains from the remaining Pseudomonas species and showed that they represent two novel species within the genus Pseudomonas for which the names Pseudomonas karstica sp. nov. (type strain HJ/4T=CCM 7891T=LMG 27930T) and Pseudomonas spelaei sp. nov. (type strain SJ/9/1T=CCM 7893T=LMG 27931T) are suggested.

Hymenobacter terrestris sp. nov. and Hymenobacter lapidiphilus sp. nov., isolated from regoliths in Antarctica.

A group of four psychrotrophic bacterial strains was isolated on James Ross Island (Antarctica) in 2013. All isolates, originating from different soil samples, were collected from the ice-free northern part of the island. They were rod-shaped, Gram-stain-negative, and produced moderately slimy red-pink pigmented colonies on R2A agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, MALDI-TOF MS, rep-PCR analyses, chemotaxonomic methods and extensive biotyping was used to clarify the taxonomic position of these isolates. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates belonged to the genus Hymenobacter. The closest relative was Hymenobacter humicola CCM 8763T, exhibiting 98.3 and 98.9% 16S rRNA pairwise similarity with the reference isolates P5342T and P5252T, respectively. Average nucleotide identity, digital DNA-DNA hybridization and core gene distances calculated from the whole-genome sequencing data confirmed that P5252T and P5342T represent two distinct Hymenobacter species. The menaquinone systems of both strains contained MK-7 as the major respiratory quinone. The predominant polar lipids for both strains were phosphatidylethanolamine and one unidentified glycolipid. The major components in the cellular fatty acid composition were summed feature 3 (C16:1 ω7c/C16:1ω6c), C16:1ω5c, summed feature 4 (anteiso-C17:1 B/iso-C17:1 I), anteiso-C15:0 and iso-C15 : 0 for all isolates. Based on the obtained results, two novel species are proposed, for which the names Hymenobacter terrestris sp. nov. (type strain P5252T=CCM 8765T=LMG 31495T) and Hymenobacter lapidiphilus sp. nov. (type strain P5342T=CCM 8764T=LMG 30613T) are suggested.

Paraclostridium dentum, a novel species with pathogenic features isolated from human dental plaque sample.

A strictly anaerobic bacterial strain designated as SKVG24 was isolated from subgingival dental plaque samples of patients suffering from periodontitis. Cells were stained Gram-positive, rod shaped with endospore. The strain showed negative reaction to catalase and oxidase enzymes, but positive for gelatinase activity. Optimal growth was observed at 37 °C temperature and 7.0 pH. The 16S rRNA gene sequence BLAST analysis assigned strain SKVG24 to the genus Paraclostridium as it displayed 99.93% identity with P. benzoelyticum JC272T followed by P. bifermentans ATCC 638T (99.79%). However, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) of the whole genome sequence showed <97% and <70% identity, respectively, with type strains of all closely related species. The G + C content of the DNA was 28.7 mol%. Total lipids profile showed presence of glycolipids as major lipids. Pathogenic features like hemolysis, gelatin hydrolysis and production of volatile sulfur compounds exhibited by strain SKVG24T were analogous to those observed in the established oral pathogenic strains. Further, whole genome sequence analysis confirmed the presence of genes encoding virulence factors and provided genomic insights on adaptation of the strain in oral environment. Based on the phenotypic and genetic differences with phylogenetic relatives, strain SKVG24T is proposed to represent a new species of the genus Paraclostridium with potential pathogenic ability, for which the name Paraclostridium dentum sp. nov., is suggested. The proposed type strain is SKVG24T (MTCC 12836T; = JCM 32760T).

Taxonomically Characterized and Validated Bacterial Species Based on 16S rRNA Gene Sequences from India During the Last Decade.

Microbial taxonomy dealing with identification and characterization of prokaryotes like bacteria and archaea has always been a major area of research all over the world. Exploring diversity of microbes and description of novel species with different genes and secondary compounds is of utmost importance for better future and sustenance of life. India having an enormous range of ecosystems and diverse species inhabiting these niches is considered to be one of the richest biodiversity regions of the world. During the last decade, with newer methodologies and better technology, the prokaryotic taxonomy from India has extended our inventory of microbial communities in specific niches. However, there still exist some limitations in classifying the microbes from India as compared to that is done world-over. This review enlists the taxonomic description of novel taxa of prokaryotes from India in the past decade. A total of 378 new bacterial species have been classified from different habitats in India in the last ten years and no descriptions of archaeal species is documented till date.

Bacterial Populations in Subgingival Plaque Under Healthy and Diseased Conditions: Genomic Insights into Oral Adaptation Strategies by Lactobacillus sp. Strain DISK7.

Human oral cavity is a complex habitat comprising about 700 microbial species and represents the most complex microbiota after gastrointestinal tract. In fact, oral microbiota directly influences health, metabolism and immune responses of the host. Metagenomic studies based on 16S rDNA profiling has reported the inhabitant bacteria mainly belonging to phyla Firmicutes, Proteobacteria, Actinobacteria, Fusobacteria, Spirochaetes and Bacteroidetes. Therefore, it is essential to isolate these strains and characterize in detail to understand their interaction. We have isolated strains from subgingival plaque from healthy to diseased individuals and the molecular characterization based on 16S rRNA gene sequence analysis showed predominance of Firmicutes, specifically members of the genus Streptococcus. Species of Lactobacillus and Veillonella were also found in significant number, which are considered as secondary colonizers. However, the population of Lactobacillus was decreased in diseased conditions with the increase in opportunistic pathogenic strains pertaining to genera like Campylobacter, Neisseria, Enterobacter, Pseudomonas and Morococcus. Further, we have also made an attempt to gain genomic insights on adaptation features and interactions of an isolate, Lactobacillus sp. strain DISK7 by performing whole genome sequencing and analysis, subsequently biochemical characterization to explore its functional and metabolic properties for the development as probiotic agent.

Clostridium indicum sp. nov., a novel anaerobic bacterium isolated from the sludge of an industrial effluent.

A strictly anaerobic bacterial strain, designated as PI-S10-A1B, was isolated from a sludge sample collected from an industrial effluent dump site at Hyderabad, India. Cells stained Gram-positive and contained terminal endospores. Optimal growth was observed at 30 °C and pH 7.0. It showed negative reactions to catalase and oxidase activities. Phylogenetic analysis of the 16S rRNA gene led to strain PI-S10-A1BT being assigned to the genus Clostridium. It displayed high sequence similarity to species of cluster XIVa including Clostridium amygdalinumBR-10T (99.84 %), Clostridium saccharolyticum WM1T (98.93 %) and Clostridium indolis DSM 755T (98.31 %). It formed a coherent cluster with members of cluster XIVa. Despite high 16S rRNA gene sequence similarity, strain PI-S10-A1BT displayed only 25.3 % identity in DNA-DNA hybridization tests with C. amygdalinum BR-10T. A draft genome exhibited low values for average nucleotide identity and in silico DNA-DNA hybridization with strains of cluster XIVa. The DNA G+C content was 42.3 mol%. Major lipids were phosphatidylglycerol and diphosphatidylglycerol, with an abundance of phosphoglycolipids. Further, analysis of the draft genome revealed genomic insights against functional aspects. Considering the phenotypic differences and low genomic identity with phylogenetic relatives, strain PI-S10-A1BT is concluded to represent a new species of the genus Clostridium, for which the name Clostridiumindicum sp. nov. is proposed with type strain PI-S10-A1BT (=MTCC 12282T=DSM 24996T=JCM 32788T).

Virgicin, a novel lanthipeptide from Virgibacillus sp. strain AK90 exhibits inhibitory activity against Gram-positive bacteria.

There is a significant increase in the discovery of new antimicrobial compounds in recent past to combat drug resistant pathogens. Members of the genus Bacillus and related genera have been screened extensively due to their ability to produce wide range of antimicrobial compounds. In this study, we have isolated and characterized a new antimicrobial peptide from a marine bacterium identified as Virgibacillus species. The low molecular mass and stability of the antimicrobial substance pointed towards the bacteriocinogenic nature of the compound. The RAST analysis of genome sequence showed presence of a putative bacteriocin biosynthetic cluster containing genes necessary for synthesis of a lanthipeptide. Translated amino acid sequence of mature C-terminal propeptide showed identity with salivaricin A (52.2%) and lacticin A (33.3%). Accordingly, the mass (2417 Da) obtained by MALDI analysis was in agreement with posttranslational modifications of the leader peptide to yield three methyl lanthionine rings and a disulfide bond between two free cysteine residues. The lanthipeptide was named as virgicin, which selectively inhibited the growth of Gram-positive bacteria and biofilm formation by Enterococcus faecalis. Inhibition of biofilm formation by E. faecalis was also observed in in vitro model experiments using hydroxyapatite discs. Thus, virgicin appears to be a promising new bacteriocin to control oral biofilm formation by selective pathogens.

Psychromicrobium lacuslunae sp. nov., isolated from a high altitude lake.

The novel strain IHBB 11108T was a psychrotolerant and alkaliphilic bacterium isolated from the subsurface water of Chandra Tal Lake in the Lahaul-Spiti valley located in the Indian trans-Himalayas. Cells were Gram-stain-positive, aerobic, non-motile, catalase-positive and oxidase-negative. The strain grew at 5-37 °C (optimum 28 °C), pH 5.0-12.0 (optimum pH 7.0) and with up to 8 % NaCl (optimum 1 %). The 16S rRNA gene sequence analysis revealed the highest relatedness of strain IHBB 11108T with Psychromicrobium silvestre DSM 102047T (97.5 %), Arthrobacter russicus DSM 14555T (97.4 %) and Renibacterium salmoninarum ATCC 33209T (97.4 %). The strain contained a quinone system with 57.2 % MK-9(H2), 39.1 % MK-10(H2), 3.0 % MK-8(H2) and 0.7 % MK-7(H2). The polar lipids detected were diphosphatidylglycerol, dimannosylglyceride, phosphatidylinositol, phosphatidylglycerol, monogalactosyldiacylglycerol, one unidentified glycolipid and four unidentified lipids. The cell-wall peptidoglycan structure type was A3α l-Lys-l-Thr-l-Ala with substitution of the α-carboxyl group of d-Glu by alanine amide. Anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 were the predominant fatty acids. The genomic DNA G+C content was 59.0 mol%. The DNA-DNA relatedness of strain IHBB 11108T was 46.7±2.2, 43.1±2.5 and 19.1±2.4 % with P. silvestre DSM 102047T, A. russicus DSM 14555T and R. salmoninarum ATCC 33209T, respectively. On the basis of the results of the phenotypic, chemotaxonomic and phylogenetic analyses, IHBB 11108T is considered to represent a novel species of the genus Psychromicrobium for which the name Psychromicrobium lacuslunae sp. nov. is proposed. The type strain is IHBB 11108T (=MTCC 12460T=MCC 2780T=JCM 31143T=KACC 19070T).

Bacteriocins: perspective for the development of novel anticancer drugs.

Antimicrobial peptides (AMPs) from prokaryotic source also known as bacteriocins are ribosomally synthesized by bacteria belonging to different eubacterial taxonomic branches. Most of these AMPs are low molecular weight cationic membrane active peptides that disrupt membrane by forming pores in target cell membranes resulting in cell death. While these peptides known to exhibit broad-spectrum antimicrobial activity, including antibacterial and antifungal, they displayed minimal cytotoxicity to the host cells. Their antimicrobial efficacy has been demonstrated in vivo using diverse animal infection models. Therefore, we have discussed some of the promising peptides for their ability towards potential therapeutic applications. Further, some of these bacteriocins have also been reported to exhibit significant biological activity against various types of cancer cells in different experimental studies. In fact, differential cytotoxicity towards cancer cells as compared to normal cells by certain bacteriocins directs for a much focused research to utilize these compounds as novel therapeutic agents. In this review, bacteriocins that demonstrated antitumor activity against diverse cancer cell lines have been discussed emphasizing their biochemical features, selectivity against extra targets and molecular mechanisms of action.

Bacillus mangrovi sp. nov., isolated from a sediment sample from a mangrove forest.

A facultatively anaerobic, endospore forming, alkali-tolerant, Gram-stain-positive, motile, rod-shaped bacterium, designated strain AK61T, was isolated from a sediment sample collected from Coringa mangrove forest, India. Colonies were circular, 1.5 mm in diameter, shiny, smooth, yellowish and convex with entire margins after 48 h growth at 30 °C. Growth occurred at 15-42 °C, with 0-3 % (w/v) NaCl and at pH 6-9. AK61T was positive for amylase activity and negative for oxidase, catalase, aesculinase, caseinase, cellulase, DNase, gelatinase, lipase and urease activities. The fatty acids were dominated by branched types with iso- and anteiso- saturated fatty acids with a high abundance of iso-C14 : 0, iso-C15 : 0, anteiso-C15 : 0 and iso-C16 : 0; the cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid; and MK-7 was the major menaquinone. DNA-DNA hybridization between AK61T and Bacillus indicus MTCC 4374T and between AK61T and Bacillus indicus KCTC 3880 showed relatedness of 37.99 and 33.32 % respectively. The DNA G+C content of AK61T was 44 mol%. The results of a blast sequence similarity search based on 16S rRNA gene sequences indicated that Bacillus cibi and Bacillus indicus were the nearest phylogenetic neighbours, with a pair-wise sequence similarity of 97.69 and 97.55 % respectively. The results of phylogenetic analysis indicated that AK61T was clustered with Bacillus idriensis and Bacillus indicus. On the basis of its phenotypic characteristics and phylogenetic inference, AK61T represents a novel species of the genus Bacillus, for which the name Bacillus mangrovi sp. nov. is proposed. The type strain is AK61T (=JCM 31087T=MTCC 12015T=KCTC 33872T).