Investigation of tRNA-based relatedness within the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) superphylum: a comparative analysis.

The PVC superphylum is a diverse group of prokaryotes that require stringent growth conditions. RNA is a fascinating molecule to find evolutionary relatedness according to the RNA World Hypothesis. We conducted tRNA gene analysis to find evolutionary relationships in the PVC phyla. The analysis of genomic data (P = 9, V = 4, C = 8) revealed that the number of tRNA genes varied from 28 to 90 in Planctomycetes and Chlamydia, respectively. Verrucomicrobia has whole genomes and the longest scaffold (3 + 1), with tRNA genes ranging from 49 to 53 in whole genomes and 4 in the longest scaffold. Most tRNAs in the E. coli genome clustered with homologs, but approximately 43% clustered with tRNAs encoding different amino acids. Planctomyces, Akkermansia, Isosphaera, and Chlamydia were similar to E. coli tRNAs. In a phylum, tRNAs coding for different amino acids clustered at a range of 8 to 10%. Further analysis of these tRNAs showed sequence similarity with Cyanobacteria, Proteobacteria, Viridiplantae, Ascomycota and Basidiomycota (Eukaryota). This indicates the possibility of horizontal gene transfer or, otherwise, a different origin of tRNA in PVC bacteria. Hence, this work proves its importance for determining evolutionary relatedness and potentially identifying bacteria using tRNA. Thus, the analysis of these tRNAs indicates that primitive RNA may have served as the genetic material of LUCA before being replaced by DNA. A quantitative analysis is required to test these possibilities that relate the evolutionary significance of tRNA to the origin of life.

Prokaryotic communities adapted to microhabitats on the Indian lotus (Nelumbo nucifera) growing in the high-altitude urban Dal Lake.

Indian lotus (Nelumbo nucifera) is one of the dominant aquatic plants cultivated in Dal Lake, situated at 1586 m above mean sea level (MSL) in the northeast of Srinagar, Kashmir. Despite their economic and ecological role, the microbial communities associated with the lotus plant are still unexplored. In this study, we investigated the prokaryotic communities on surfaces of different lotus microhabitats (roots, rhizome, leaves, flowers, and fruits), lake water, and sediments using 16S rRNA gene amplicon sequencing. Overall, prokaryotic diversity decreased significantly on the surface of lotus microhabitats in comparison to the lake water and sediments. Among the microhabitats of lotus, roots and leaves harbored more diverse communities in comparison to rhizomes, fruits, and flowers. A total of 98 genera were shared by lotus and the Dal Lake sediments and water. However, significant differences were found in their relative abundance; for example, Pseudomonas was the most dominant genus on the majority of lotus microhabitats. On the other hand, Flavobacterium was highly abundant in the lake water, while a higher abundance of Acinetobacter was recorded in sediments. Additionally, we also noted the presence of potential human pathogenic genera including Escherichia-Shigella, Enterobacter, Pantoea, Raoultella, Serratia, and Sphingomonas on the lotus microhabitats. Predicted functions of prokaryotic communities revealed a higher abundance of genes associated with nutrient uptake in the microhabitats of the lotus. This study offered first-hand information on the prokaryotic communities harbored by lotus plants and water and sediments of the Dal Lake and demonstrated the adaptation of diverse communities to microhabitats of lotus.

Colonization with non-mycorrhizal culturable endophytic fungi enhances orchid growth and indole acetic acid production.

BACKGROUND: Symbiotic associations of endophytic fungi have been proved by possessing an ability to produce hormones and metabolites for their host plant. Members of the Orchidaceae are obligate mycorrhizal species but a non-mycorrhizal association needs more investigation for their ability to promote plant growth and produce plant growth hormones. In the present study, endophytic fungi were isolated from the roots of Dendrobium longicornu Lindl., to investigate the root colonizing activity and role in plant growth and development. RESULTS: Among 23 fungal isolates were identified both by morphological and molecular technique as Penicillium sp., Fusarium sp., Coniochaeta sp., Alternaria sp., and Cladosporium sp. The dominate species were Coniochaeta sp. and Cladosporium sp. The dominant species as per the isolation was Coniochaeta sp. These fungal strains were screened for growth-promoting activity of Cymbidium aloifolium (plantlet) consider as cross genus interaction and Dendrobium longicornu (protocorms) as a host plant in in-vitro condition. Importantly, Cladosporium sp., and Coniochaeta sp. showed successful colonization and peloton formation with roots of C. aloifolium. Moreover, it also enhanced acclimatization of plantlets. Fungal elicitors from nine fungal isolates enhanced the growth of the in vitro grown protocorms of D. longicornu. Key bioactive compounds detected in the fungal colonized plant extract were 2H-pyran-2-one, Cyclopropanecarboxylic acid, Oleic Acid and d-Mannitol, which may have a potential role in plant-microbe interaction. All fungal endophytes were able to synthesize the indole acetic acid (IAA) in presence of tryptophan. Moreover, fungal extract DLCCR7 treated with DL-tryptophan yielded a greater IAA concentration of 43 µg per ml than the other extracts. The iaaM gene involved in IAA synthesis pathway was amplified using iaaM gene primers successfully from Alternaria sp., Cladosporium sp., and Coniochaeta sp. CONCLUSIONS: Hence, this study confirms the production of IAA by endophytes and demonstrated their host as well as cross-genus plant growth-promoting potential by producing metabolites required for the growth of the plant.

Cultivable microbial diversity in speleothems using MALDI-TOF spectrometry and DNA sequencing from Krem Soitan, Krem Lawbah, Krem Mawpun, Khasi Hills, Meghalaya, India.

The microbial diversity in the Indian caves is inadequately characterized. This study reports on the culturable microbial communities in caves from the Indian sub-continent. This study aims to expand the current understanding of bacterial diversity in the speleothems and wall deposits from Krem Soitan, Krem Lawbah, Krem Mawpun in Khasi Hills, Meghalaya, India. A culture-dependent approach was employed for elucidating the community structure in the caves using MALDI-TOF spectrometry and 16S rRNA gene sequencing. A high bacterial diversity and a greater bacterial taxonomic diversity is reported using MALDI-TOF spectrometry and 16S rRNA gene sequencing. High microbial enumerations were observed on dilute nutrient agar (5.3 × 103 to 8.8 × 105) followed by M9 minimal medium (4 × 104 to 1.7 × 105) and R2A medium (1.0 × 104 to 5.7 × 105). A total of 826 bacterial isolates were selected and preserved for the study. 295 bacterial isolates were identified using MALDI-TOF spectrometry and the isolates which showed no reliable peaks were further identified by 16S rRNA gene sequencing. A total 91% of the bacterial diversity was dominated by Proteobacteria (61%) and Actinobacteria (30%). In addition, bacterial phyla include Firmicutes (7.45%), Deinococcus-Thermus (0.33%) and Bacteroidetes (0.67%) were found in the samples. At the genus level, Pseudomonas (55%) and Arthrobacter (23%) were ubiquitous followed by Acinetobacter, Bacillus, Brevundimonas, Deinococcus, Flavobacterium, Paenibacillus, Pseudarthrobacter. Multivariate statistical analysis indicated that the bacterial genera formed separate clusters depending on the geochemical constituents in the spring waters suitable for their growth and metabolism. To the best of our knowledge, there are no previous geomicrobiological investigations in these caves and this study is a pioneering culture dependent study of the microbial community with many cultured isolates.

Mining the landfill soil metagenome for denitrifying methanotrophic taxa and validation of methane oxidation in microcosm.

In the present study, the microbial community residing at different depths of the landfill was characterized to assess their roles in serving as a methane sink. Physico-chemical characterization revealed the characteristic signatures of anaerobic degradation of organic matter in the bottom soil (50-60 cm) and, active process of aerobic denitrification in the top soil (0-10 cm). This was also reflected from the higher abundance of bacterial domain in the top soil metagenome represented by dominant phyla Proteobacteria and Actinobacteria which are prime decomposers of organic matter in landfill soils. The multiple fold higher relative abundances of the two most abundant genera; Streptomyces and Intrasporangium in the top soil depicted greater denitrifying taxa in top soil than the bottom soil. Amongst the aerobic methanotrophs, the genera Methylomonas, Methylococcus, Methylocella, and Methylacidiphilum were abundantly found in the top soil metagenome that were essential for oxidizing methane generated in the landfill. On the other hand, the dominance of archaeal domain represented by Methanosarcina and Methanoculleus in the bottom soil highlighted the complete anaerobic digestion of organic components via acetoclasty, carboxydotrophy, hydrogenotrophy, methylotrophy. Functional characterization revealed a higher abundance of methane monooxygenase gene in the top soil and methyl coenzyme M reductase gene in the bottom soil that correlated with the higher relative abundance of aerobic methanotrophs in the top soil while methane generation being the active process in the highly anaerobic bottom soil in the landfill. The activity dependent abundance of endogenous microbial communities in the different zones of the landfill was further validated by microcosm studies in serum bottles which established the ability of the methanotrophic community for methane metabolism in the top soil and their potential to serve as sink for methane. The study provides a better understanding about the methanotrophs in correlation with their endogenous environment, so that these bacteria can be used in resolving the environmental issues related to methane and nitrogen management at landfill site.

MicFunPred: A conserved approach to predict functional profiles from 16S rRNA gene sequence data.

The 16S rRNA gene amplicon sequencing is a popular technique that provides accurate characterization of microbial taxonomic abundances but does not provide any functional information. Several tools are available to predict functional profiles based on 16S rRNA gene sequence data that use different genome databases and approaches. As variable regions of partially-sequenced 16S rRNA gene cannot resolve taxonomy accurately beyond the genus level, these tools may give inflated results. Here, we developed 'MicFunPred', which uses a novel approach to derive imputed metagenomes based on a set of core genes only, thereby minimizing false-positive predictions. On simulated datasets, MicFunPred showed the lowest False Positive Rate (FPR) with mean Spearman's correlation of 0.89 (SD = 0.03), while on seven real datasets the mean correlation was 0.75 (SD = 0.08). MicFunPred was found to be faster with low computational requirements and performed better or comparable when compared with other tools.

A prospectus of plant growth promoting endophytic bacterium from orchid (Vanda cristata).

BACKGROUND: A plant growth-promoting endophytic bacterium PVL1 isolated from the leaf of Vanda cristata has the ability to colonize with roots of plants and protect the plant. PVL1 was isolated using laboratory synthetic media. 16S rRNA gene sequencing method has been employed for identification before and after root colonization ability. RESULTS: Original isolated and remunerated strain from colonized roots were identified as Bacillus spp. as per EzBiocloud database. The presence of bacteria in the root section of the plantlet was confirmed through Epifluorescence microscopy of colonized roots. The in-vitro plantlet colonized by PVL1 as well as DLMB attained higher growth than the control. PVL1 capable of producing plant beneficial phytohormone under in vitro cultivation. HPLC and GC-MS analysis suggest that colonized plants contain Indole Acetic Acid (IAA). The methanol extract of Bacillus spp., contains 0.015 µg in 1 µl concentration of IAA. PVL1 has the ability to produce antimicrobial compounds such as ethyl iso-allocholate, which exhibits immune restoring property. One-way ANOVA shows that results were statistically significant at P ≤ 0.05 level. CONCLUSIONS: Hence, it has been concluded that Bacillus spp. PVL1 can promote plant growth through secretion of IAA during root colonization and ethyl iso-allocholate to protect plants from foreign infections. Thus, this study supports to support Koch's postulates of bacteria establishment.

Disruptions in oral and nasal microbiota in biomass and tobacco smoke associated chronic obstructive pulmonary disease.

Chronic exposures to tobacco and biomass smoke are the most prevalent risk factors for COPD development. Although microbial diversity in tobacco smoke-associated COPD (TSCOPD) has been investigated, microbiota in biomass smoke-associated COPD (BMSCOPD) is still unexplored. We aimed to compare the nasal and oral microbiota between healthy, TSCOPD, and BMSCOPD subjects from a rural population in India. Nasal swabs and oral washings were collected from healthy (n = 10), TSCOPD (n = 11), and BMSCOPD (n = 10) subjects. The downstream analysis was performed using QIIME pipeline (v1.9). In nasal and oral microbiota no overall differences were noted, but there were key taxa that had differential abundance in either Healthy vs COPD and/or TSCOPD vs. BMSCOPD. Genera such as Actinomyces, Actinobacillus, Megasphaera, Selenomonas, and Corynebacterium were significantly higher in COPD subjects. This study suggests that microbial community undergoes dysbiosis which may further contribute to the progression of disease. Thus, it is important to identify etiological agents for such a polymicrobial alterations which contribute highly to the disease manifestation.

Contrasting Composition, Diversity and Predictive Metabolic Potential of the Rhizobacterial Microbiomes Associated with Native and Invasive Prosopis Congeners.

Invasive plants are known to alter the soil microbial communities; however, the effects of co-occurring native and invasive congeners on the soil bacterial diversity and their predictive metabolic profiles are not known. Here, we compared the rhizosphere bacterial communities of invasive Prosopis juliflora and its native congener Prosopis cineraria using high-throughput sequencing of the 16S rRNA gene. Unweighted Pair Group Method with Arithmetic mean (UPGMA) based dendrogram revealed significant variation in the communities of these co-occurring Prosopis species. Additionally, Canonical Correspondence Analysis (CCA) based on microbial communities in addition to the soil physiochemical parameters viz. soil pH, electrical conductivity, moisture content and sampling depth showed ~ 80% of the variation in bacterial communities of the rhizosphere and control soil. We observed that Proteobacteria was the predominant phylum of P. juliflora rhizosphere and the control soil, while P. cineraria rhizosphere was dominated by Cyanobacteria. Notably, the invasive P. juliflora rhizosphere showed an enhanced abundance of bacterial phyla like Actinobacteria, Chloroflexi, Firmicutes and Acidobacteria compared to the native P. cineraria as well as the control soil. Predictive metagenomics revealed that the bacterial communities of the P. juliflora rhizosphere had a higher abundance of pathways involved in antimicrobial biosynthesis and degradation, suggesting probable exposure to enemy attack and an active response mechanism to counter it as compared to native P. cineraria. Interestingly, the higher antimicrobial biosynthesis predicted in the invasive rhizosphere microbiome is further corroborated by the fact that the bacterial isolates purified from the rhizosphere of P. juliflora belonged to genera like Streptomyces, Isoptericola and Brevibacterium from the phylum Actinobacteria, which are widely reported for their antibiotic production ability. In conclusion, our results demonstrate that the co-occurring native and invasive Prosopis species have significantly different rhizosphere bacterial communities in terms of composition, diversity and their predictive metabolic potentials. In addition, the rhizosphere microbiome of invasive Prosopis proffers it a fitness advantage and influences invasion success of the species.

Integrated Genomic and Functional Characterization of the Anti-diabetic Potential of Arthrobacter sp. SW1.

For decades, bacterial natural products have served as valuable resources for developing novel drugs to treat several human diseases. Recent advancements in the integrative approach of using genomic and functional tools have proved beneficial in obtaining a comprehensive understanding of these biomolecules. This study presents an in-depth characterization of the anti-diabetic activity exhibited by a bacterial isolate SW1, isolated from an effluent treatment plant. As a primary screening, we assessed the isolate for its potential to inhibit alpha-amylase and alpha-glucosidase enzymes. Upon confirmation, we further utilized LC-MS, ESI-MS/MS, and NMR spectroscopy to identify and characterize the biomolecule. These efforts were coupled with the genomic assessment of the biosynthetic gene cluster involved in the anti-diabetic compound production. Our investigation discovered that the isolate SW1 inhibited both α-amylase and α-glucosidase activity. The chemical analysis suggested the production of acarbose, an anti-diabetic biomolecule, which was further confirmed by the presence of biosynthetic gene cluster "acb" in the genome. Our in-depth chemical characterization and genome mining approach revealed the potential of bacteria from an unconventional niche, an effluent treatment plant. To the best of our knowledge, it is one of the first few reports of acarbose production from the genus Arthrobacter.

Human gut-derived commensal suppresses generation of T-cell response to gliadin in humanized mice by modulating gut microbiota.

The human intestinal tract is colonized by a large number of diverse microorganisms that play various important physiologic functions. In inflammatory gut diseases including celiac disease (CeD), a dysbiotic state of microbiome has been observed. Interestingly, this perturbed microbiome is normalized towards eubiosis in patients showing recovery after treatment. The treatment has been observed to increase the abundance of beneficial microbes in comparison to non-treated patients. In this study, we investigated the effect of Prevotella histicola or Prevotella melaninogenica, isolated from the duodenum of a treated CeD patient, on the induction and maintenance of oral tolerance to gliadin, a CeD associated subgroup of gluten proteins, in NOD.DQ8.ABo transgenic mice. Conventionally raised mice on a gluten free diet were orally gavaged with bacteria before and after injection with pepsin trypsin digested gliadin (PTD-gliadin). P. histicola suppressed the cellular response to gliadin, whereas P. melaninogenica failed to suppress an immune response against gliadin. Interestingly, tolerance to gliadin in NOD.DQ8.ABo mice may be associated with gut microbiota as mice gavaged with P melaninogenica harbored a different microbial diversity as compared to P. histicola treated mice. This study provides experimental evidence that gut microbes like P. histicola from treated patients can suppress the immune response against gliadin epitopes.

Bacterial Communities Associated with the Biofilms Formed in High-Altitude Brackish Water Pangong Tso Located in the Himalayan Plateau.

Pangong Tso is a long and narrow lake situated at an altitude of ~ 4266 m amsl in the Himalayan Plateau on the side of the India/China border. Biofilm has been observed in a small area near the shore of Pangong Tso. Bacterial communities of the lake sediment, water and biofilms were studied using amplicon sequencing of V3-V4 region of the 16S rRNA gene. The standard QIIME pipeline was used for analysis. The metabolic potential of the community was predicted using functional prediction tool Tax4Fun. Bacterial phyla Proteobacteria, followed by Bacteroidetes, Acidobacteria, Planctomycetes, Actinobacteria, and Firmicutes, were found to be dominant across these samples. Shannon's and Simpson's alpha diversity analysis revealed that sediment communities are the most diverse, and water communities are the least diverse. Principal Coordinates based beta diversity analysis showed significant variation in the bacterial communities of the water, sediment and biofilm samples. Bacterial phyla Verrucomicrobia, Deinococcus-Thermus and Cyanobacteria were explicitly enriched in the biofilm samples. Predictive functional profiling of these bacterial communities showed a higher abundance of genes involved in photosynthesis, biosynthesis of secondary metabolites, carbon fixation in photosynthetic organisms and glyoxylate and dicarboxylate metabolism in the biofilm sample. In conclusion, the Pangong Tso bacterial communities are quite similar to other saline and low-temperature lakes in the Tibetan Plateau. Bacterial community structure of the biofilm samples was significantly different from that of the water and sediment samples and enrichment of saprophytic communities was observed in the biofilm samples, indicating an important succession event in this high-altitude lake.

Diversity of Onygenalean Fungi in Keratin-Rich Habitats of Maharashtra (India) and Description of Three Novel Taxa.

Extensive survey was carried out in the state of Maharashtra, India, as part of a 3-year project to explore keratinophilic fungal diversity for conservation and biotechnological potential. A total of 578 soil samples were collected from keratin-rich habitats across 24 districts of Maharashtra State. Hair-baiting technique and micro-dilution drop-trail method were employed for isolation and purification of keratinophilic fungi from soil. A total of 66 species belonging to 17 genera of order Onygenales were recorded in hair baits. Eleven taxa were found to be new to science, most of which were rare as they were recorded in only one sample out of the > 500 samples analyzed. Three novel taxa have been characterized at morphological and molecular level and described here as new to science. These taxa include Currahmyces indicus gen. et sp. nov., Canomyces reticulatus gen. et sp. nov., Ctenomyces indicus sp. nov. All these novel taxa are morphologically and phylogenetically distinct from known taxa of order Onygenales. The study indicates that systematic sampling of a larger area is needed to uncover the hidden (unknown) diversity of keratinophilic fungi which is overlooked in sporadic samplings as evident from previous studies.

Bacterial load and defective monocyte-derived macrophage bacterial phagocytosis in biomass smoke-related COPD.

Lower airway colonisation with species of potentially pathogenic bacteria (PPB) is associated with defective bacterial phagocytosis, in monocyte-derived macrophages (MDMs) and alveolar macrophages, from tobacco smoke-associated chronic obstructive pulmonary disease (S-COPD) subjects. In the developing world, COPD among nonsmokers is largely due to biomass smoke (BMS) exposure; however, little is known about PPB colonisation and its association with impaired innate immunity in these subjects.We investigated the PPB load (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Pseudomonas aeruginosa) in BMS-exposed COPD (BMS-COPD) subjects compared with S-COPD and spirometrically normal subjects. We also examined the association between PPB load and phagocytic activity of MDMs and lung function. Induced sputum and peripheral venous blood samples were collected from 18 healthy nonsmokers, 15 smokers without COPD, 16 BMS-exposed healthy subjects, 19 S-COPD subjects and 23 BMS-COPD subjects. PPB load in induced sputum and MDM phagocytic activity were determined using quantitative PCR and fluorimetry, respectively.Higher bacterial loads of S. pneumoniae, H. influenzae and P. aeruginosa were observed in BMS-COPD subjects. Increased PPB load in BMS-exposed subjects was significantly negatively associated with defective phagocytosis in MDMs and spirometric lung function indices (p<0.05).Increased PPB load in airways of BMS-COPD subjects is inversely associated with defective bacterial phagocytosis and lung function.

Diversity and Succession of Microbiota during Fermentation of the Traditional Indian Food Idli.

Idli, a naturally fermented Indian food, is prepared from a mixture of rice and black gram (lentil). To understand its microbial community during fermentation, detailed analysis of the structural and functional dynamics of the idli microbiome was performed by culture-dependent and -independent approaches. The bacterial diversity and microbial succession were assessed at different times of fermentation by 16S rRNA amplicon sequencing. Results highlighted that most microbiota belonged to phylum Firmicutes (70%) and Proteobacteria (22%). Denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) analysis confirmed the diversity and succession involved therein. A culture-dependent approach revealed that the microbially diverse populations were conserved across different geographical locations. The fermentation was primarily driven by lactic acid bacteria as they constitute 86% of the total bacterial population, and genus Weissella emerged as the most important organism in fermentation. The natural microbiota of the grains mainly drives the fermentation, as surface sterilized grains did not show any fermentation. Growth kinetics of idli microbiota and physicochemical parameters corroborated the changes in microbial dynamics, acid production, and leavening occurring during fermentation. Using a metagenomic prediction tool, we found that the major metabolic activities of these microbial fermenters were augmented during the important phase of fermentation. The involvement of the heterofermentative hexose monophosphate (HMP) pathway in batter leavening was substantiated by radiolabeled carbon dioxide generated from d-[1-14C]-glucose. Hydrolases degrading starch and phytins and the production of B vitamins were reported. Moreover, culturable isolates showing beneficial attributes, such as acid and bile tolerance, hydrophobicity, antibiotic sensitivity, and antimicrobial activity, suggest idli to be a potential dietary supplement.IMPORTANCE This is a comprehensive analysis of idli fermentation employing modern molecular tools which provided valuable information about the bacterial diversity enabling its fermentation. The study has demonstrated the relationship between the bacterial population and its functional role in the process. The nature of idli fermentation was found to be more complex than other food fermentations due to the succession of the bacterial population. Further studies using metatranscriptomics and metabolomics may enhance the understanding of this complex fermentation process. Moreover, the presence of microorganisms with beneficial properties plausibly makes idli a suitable functional food.

Mining the Core Gut Microbiome from a Sample Indian Population.

Human gut microbiome studies are increasing at a rapid pace to understand contributions of the prokaryotic life to the innate workings of their eukaryotic host. Majority of studies focus on the pattern of gut microbial diversity in various diseases, however, understanding the core microbiota of healthy individuals presents a unique opportunity to study the microbial fingerprint in population specific studies. Present study was undertaken to determine the core microbiome of a healthy population and its imputed metabolic role. A total of 8990, clone library sequences (> 900 bp) of 16S rRNA gene from fecal samples of 43 individuals were used. The core gut microbiota was computed using QIIME pipeline. Our results show the distinctive predominance of genus Prevotella and the core composition of genera Prevotella, Bacteroides, Roseburia and Megasphaera in the Indian gut. PICRUSt analysis for functional imputation of the microbiome indicates a higher potential of the microbiota for carbohydrate metabolism. The presence of core microbiota may indicate key functions played by these microbes for the human host.

Comparative genome analysis reveals key genetic factors associated with probiotic property in Enterococcus faecium strains.

BACKGROUND: Enterococcus faecium though commensal in the human gut, few strains provide a beneficial effect to humans as probiotics while few are responsible for the nosocomial infection. Comparative genomics of E. faecium can decipher the genomic differences responsible for probiotic, pathogenic and non-pathogenic properties. In this study, we compared E. faecium strain 17OM39 with a marketed probiotic, non-pathogenic non-probiotic (NPNP) and pathogenic strains. RESULTS: E. faecium 17OM39 was found to be closely related with marketed probiotic strain T110 based on core genome analysis. Strain 17OM39 was devoid of known vancomycin, tetracycline resistance and functional virulence genes. Moreover, E. faecium 17OM39 genome was found to be more stable due to the absence of frequently found transposable elements. Genes imparting beneficial functional properties were observed to be present in marketed probiotic T110 and 17OM39 strains. Genes associated with colonization and survival within gastrointestinal tract was also detected across all the strains. CONCLUSIONS: Beyond shared genetic features; this study particularly identified genes that are responsible for imparting probiotic, non-pathogenic and pathogenic features to the strains of E. faecium. Higher genomic stability, absence of known virulence factors and antibiotic resistance genes and close genomic relatedness with marketed probiotics makes E. faecium 17OM39 a potential probiotic candidate. The work presented here demonstrates that comparative genome analyses can be applied to large numbers of genomes, to find potential probiotic candidates.

Genomic and physiological analyses of an indigenous strain, Enterococcus faecium 17OM39.

The human gut microbiome plays a crucial role in human health and efforts need to be done for cultivation and characterisation of bacteria with potential health benefits. Here, we isolated a bacterium from a healthy Indian adult faeces and investigated its potential as probiotic. The cultured bacterial strain 17OM39 was identified as Enterococcus faecium by 16S rRNA gene sequencing. The strain 17OM39 exhibited tolerance to acidic pH, showed antimicrobial activity and displayed strong cell surface traits such as hydrophobicity and autoaggregation capacity. The strain was able to tolerate bile salts and showed bile salt hydrolytic (BSH) activity, exopolysaccharide production and adherence to human HT-29 cell line. Importantly, partial haemolytic activity was detected and the strain was susceptible to the human serum. Genomics investigation of strain 17OM39 revealed the presence of diverse genes encoding for proteolytic enzymes, stress response systems and the ability to produce essential amino acids, vitamins and antimicrobial compound Bacteriocin-A. No virulence factors and plasmids were found in this genome of the strain 17OM39. Collectively, these physiological and genomic features of 17OM39 confirm the potential of this strain as a candidate probiotic.

Microbacterium telephonicum sp. nov., isolated from the screen of a cellular phone.

A cultivation-based study of the microbial diversity of cellular phone screens led to the isolation of a Gram-stain-positive, aerobic, rod-shaped and non-endospore-forming bacterium, designated S2T63T, exhibiting phenotypic and genotypic characteristics unique to the type strains of closely related species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain is a member of Microbacterium, and most closely related to Microbacterium aurantiacum IFO 15234T and Microbacterium kitamiense Kitami C2T. The DNA-DNA relatedness values of the strain S2T63T to M. aurantiacum KACC 20510T, M. kitamiense KACC 20514Tand Microbacterium laevaniformans KACC 14463T were 65 % (±4), 29.5 % (±3) and 55.9 % (±4), respectively. The genomic DNA G+C content was 71.8 mol%. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0, C16 : 0 and anteiso-C17 : 0. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and two unidentified polar lipids. The peptidoglycan contained the amino acids glycine, lysine, alanine and glutamic acid, with substantial amounts of hydroxy glutamic acid detected, which is characteristic of peptidoglycan type B1α. The predominant menaquinones were MK-12 and MK-13. Rhamnose, fucose and galactose were the whole-cell sugars detected. The strain also showed biofilm production, estimated by using crystal violet assay. Based on the results of the phenotypic and genotypic characterizations, it was concluded that the new strain represents a novel species of the genus Microbacterium, for which the name Microbacteriumtelephonicum is proposed, with S2T63T (=MCC 2967T=KACC 18715T=LMG 29293T) as the type strain.

Characterization of Solibacillus silvestris strain AM1 that produces amyloid bioemulsifier.

Solibacillus silvestris AM1 was the first strain from the genus to be reported for the production of a functional amyloid and its potential use as a surface active agent, a thermostable glycoprotein amyloid bioemulsifier BE-AM1 capable of influencing environment and biofilm formation. Phylogenetic analysis based on 16S rRNA gene, molecular characterization studies on the basis of DNA-DNA hybridization and chemotaxonomic fatty acid methyl ester (FAME) analysis showed that S. silvestris AM1 as a strain matches with the type strain S. silvestris HR3-23. But strain AM1 differs from the type strain HR3-23 in carbon substrate utilization studies along with amyloid bioemulsifier production ability with potential industrial and environmental applications. S. silvestris AM1 exhibited bioemulsifier production at wide range of factors like pH and NaCl concentrations, while temperature influenced the bioemulsifier production indirectly (since it affected the growth). Bioemulsifier production was observed even at oligotrophic conditions (0.5 mg ml-1 ) seen usually in its native environment. In this study, we have characterized the amyloid producing S. silvestris AM1 taxonomically and also analyzed 16S rDNA of 103 sequences of Solibacillus sp. available, which indicated the possibility of new species in this genus and can be studied for industrially and environmentally important biomolecules.