Dhiraj P. Dhotre

Molecular analysis of gut microbiota in obesity among Indian individuals

Obesity is a consequence of a complex interplay between the host genome and the prevalent obesogenic factors among the modern communities. The role of gut microbiota in the pathogenesis of the disorder was recently discovered; however, 16S-rRNA-based surveys revealed compelling but community-specific data. Considering this, despite unique diets, dietary habits and an uprising trend in obesity, the Indian counterparts are poorly studied. Here, we report a comparative analysis and quantification of dominant gut microbiota of lean, normal, obese and surgically treated obese individuals of Indian origin. Representative gut microbial diversity was assessed by sequencing fecal 16S rRNA libraries for each group (n = 5) with a total of over 3000 sequences. We detected no evident trend in the distribution of the predominant bacterial phyla, Bacteroidetes and Firmicutes. At the genus level, the bacteria of genus Bacteroides were prominent among the obese individuals, which was further confirmed by qPCR (P < 0.05). In addition, a remarkably high archaeal density with elevated fecal SCFA levels was also noted in the obese group. On the contrary, the treated-obese individuals exhibited comparatively reduced Bacteroides and archaeal counts along with reduced fecal SCFAs. In conclusion, the study successfully identified a representative microbial diversity in the Indian subjects and demonstrated the prominence of certain bacterial groups in obese individuals; nevertheless, further studies are essential to understand their role in obesity.

Characterization of bacterial community shift in human Ulcerative Colitis patients revealed by Illumina based 16S rRNA gene amplicon sequencing

BackgroundThe healthy human intestine is represented by the presence of bacterial communities predominantly belonging to obligate anaerobes; however disparity and dysanaerobiosis in intestinal microflora may lead to the progression of ulcerative colitis (UC). The foremost aim of this study is to consider and compare the gut microbiota composition in patients suffering from different stages of UC.MethodsThis study represents data from the biopsy samples of six individuals suffering from UC. The samples were collected by colonoscopy and were processed immediately for isolation of DNA. Mucosal microbiota was analyzed by means of 16S rRNA gene-based Illumina high throughput sequencing. Quantitative real-time PCR (qPCR) was performed to determine total bacterial abundances.ResultsAnalysis of 23,927 OTUs demonstrated a significant reduction of bacterial diversity consistently from phylum to species level (p < 0.05) for individuals suffering from severe stage of UC. Significant increase in abundance of unusual aerobes and facultative anaerobes, including members from the phylum Proteobacteria (p- = 0.031) was also observed. A 10 fold increase in the total bacterial count was detected in patients suffering from severe inflammatory stage (2.98 +/-0.49 E + 09/ml) when compared with patients with moderate (1.03+/-0.29 E + 08/ml) and mild (1.76 +/-0.34 E + 08/ml) stages of inflammation.ConclusionThe reduction of bacterial diversity with an increase in the total bacterial count indicates a shift of bacterial communities which signifies dysbiosis and dysanaerobiosis at the mucosal level for patients suffering from UC.

Molecular Characterization and Meta-Analysis of Gut Microbial Communities Illustrate Enrichment of Prevotella and Megasphaera in Indian Subjects

The gut microbiome has varied impact on the wellbeing of humans. It is influenced by different factors such as age, dietary habits, socio-economic status, geographic location, and genetic makeup of individuals. For devising microbiome-based therapies, it is crucial to identify population specific features of the gut microbiome. Indian population is one of the most ethnically, culturally, and geographically diverse, but the gut microbiome features remain largely unknown. The present study describes gut microbial communities of healthy Indian subjects and compares it with the microbiota from other populations. Based on large differences in alpha diversity indices, abundance of 11 bacterial phyla and individual specific OTUs, we report inter-individual variations in gut microbial communities of these subjects. While the gut microbiome of Indians is different from that of Americans, it shared high similarity to individuals from the Indian subcontinent i.e., Bangladeshi. Distinctive feature of Indian gut microbiota is the predominance of genus Prevotella and Megasphaera. Further, when compared with other non-human primates, it appears that Indians share more OTUs with omnivorous mammals. Our metagenomic imputation indicates higher potential for glycan biosynthesis and xenobiotic metabolism in these subjects. Our study indicates urgent need of identification of population specific microbiome biomarkers of Indian subpopulations to have more holistic view of the Indian gut microbiome and its health implications.

Determination of Wolbachia diversity in butterflies from Western Ghats, India, by a multigene approach.

ABSTRACT Members of the genus Wolbachia are intracellular bacteria that are widespread in arthropods and establish diverse symbiotic associations with their hosts, ranging from mutualism to parasitism. Here we present the first detailed analyses of Wolbachia in butterflies from India with screening of 56 species. Twenty-nine species (52%) representing five families were positive for Wolbachia. This is the first report of Wolbachia infection in 27 of the 29 species; the other two were reported previously. This study also provides the first evidence of infection in the family Papilionidae. A striking diversity was observed among Wolbachia strains in butterfly hosts based on five multilocus sequence typing (MLST) genes, with 15 different sequence types (STs). Thirteen STs are new to the MLST database, whereas ST41 and ST125 were reported earlier. Some of the same host species from this study carried distinctly different Wolbachia strains, whereas the same or different butterfly hosts also harbored closely related Wolbachia strains. Butterfly-associated STs in the Indian sample originated by recombination and point mutation, further supporting the role of both processes in generating Wolbachia diversity. Recombination was detected only among the STs in this study and not in those from the MLST database. Most of the strains were remarkably similar in their wsp genotype, despite divergence in MLST. Only two wsp alleles were found among 25 individuals with complete hypervariable region (HVR) peptide profiles. Although both wsp and MLST show variability, MLST gives better separation between the strains. Completely different STs were characterized for the individuals sharing the same wsp alleles.

Diversity of Wolbachia in Odontotermes spp. (Termitidae) and Coptotermes heimi (Rhinotermitidae) using the multigene approach.

The intracellular bacteria, Wolbachia, are well known for inducing reproductive alterations in arthropod hosts, especially insects. The ancient origin and huge diversity, combined with the ecological, biological and behavioral plasticity of termites, make the latter exciting candidates for studying the interactions of Wolbachia. In the present study, we investigated the distribution of Wolbachia in populations of Odontotermes spp. and Coptotermes heimi termites occurring in 14 colonies (12 Odontotermes spp. and two C. heimi) from different locations in India. A striking diversity was observed among Wolbachia strains in closely related hosts based on five MLST genes (ftsZ, coxA, fbpA, hcpA and gatB) and the 16S rRNA gene. Wolbachia variants from two supergroups (B and F) were found in both the termite genera under study. This is the first report of Wolbachia infection in the Odontotermes genus. Although F Wolbachia supergroup infection is already reported in Coptotermes lacteus and Coptotermes acinaciformis, in this study, the two C. heimi species exhibited infection by two distinctly different Wolbachia supergroups (B and F).

Generation, annotation, and analysis of ESTs from midgut tissue of adult female Anopheles stephensi mosquitoes

BackgroundMalaria is a tropical disease caused by protozoan parasite, Plasmodium, which is transmitted to humans by various species of female anopheline mosquitoes. Anopheles stephensi is one such major malaria vector in urban parts of the Indian subcontinent. Unlike Anopheles gambiae, an African malaria vector, transcriptome of A. stephensi midgut tissue is less explored. We have therefore carried out generation, annotation, and analysis of expressed sequence tags from sugar-fed and Plasmodium yoelii infected blood-fed (post 24 h) adult female A. stephensi midgut tissue.ResultsWe obtained 7061 and 8306 ESTs from the sugar-fed and P. yoelii infected mosquito midgut tissue libraries, respectively. ESTs from the combined dataset formed 1319 contigs and 2627 singlets, totaling to 3946 unique transcripts. Putative functions were assigned to 1615 (40.9%) transcripts using BLASTX against UniProtKB database. Amongst unannotated transcripts, we identified 1513 putative novel transcripts and 818 potential untranslated regions (UTRs). Statistical comparison of annotated and unannotated ESTs from the two libraries identified 119 differentially regulated genes. Out of 3946 unique transcripts, only 1387 transcripts were mapped on the A. gambiae genome. These also included 189 novel transcripts, which were mapped to the unannotated regions of the genome. The EST data is available as ESTDB at http://mycompdb.bioinfo-portal.cdac.in/cgi-bin/est/index.cgi.Conclusion3946 unique transcripts were successfully identified from the adult female A. stephensi midgut tissue. These data can be used for microarray development for better understanding of vector-parasite relationship and to study differences or similarities with other malaria vectors. Mapping of putative novel transcripts from A. stephensi on the A. gambiae genome proved fruitful in identification and annotation of several genes. Failure of some novel transcripts to map on the A. gambiae genome indicates existence of substantial genomic dissimilarities between these two potent malaria vectors.

Draft genome of Ochrobactrum intermedium strain M86 isolated from non-ulcer dyspeptic individual from India

BackgroundOchrobactrum intermedium is an emerging opportunistic pathogen of humans that is closely related to members of the genus Brucella. Earlier, we reported the case of an Indian subject with non-ulcer dyspeptic symptoms whose urease positive gastric biopsy revealed the presence of Helicobacter pylori along with non-Helicobacter like bacteria, eventually cultured and identified as O. intermedium strain M86.ResultsHere, we describe the unclosed draft genome of the strain M86 with a length of 5,188,688 bp and mean G+C content of 57.9%. We have also identified many putative gene clusters that might be responsible for its persistence in the gastric mucosa.Comparative analysis of genomic features of Ochrobactrum intermedium strain M86 and Ochrobactrum intermedium LMG 3301T was also done.ConclusionsThis paper attempts to gain whole-genome based insights into the putative gene determinants of O. intermedium for survival in the highly acidic stomach lumen environment .Identification of genes putatively involved in the various metabolic pathways may lead to a better understanding of the survival of O. intermdedium in acidic condition.

A cross-sectional comparative study of gut bacterial community of Indian and Finnish children

The human gut microbiome plays a crucial role in the compositional development of gut microbiota. Though well documented in western pediatrics population, little is known about how various host conditions affect populations in different geographic locations such as the Indian subcontinent. Given the impact of distinct environmental conditions, our study assess the gut bacterial diversity of a small cohort of Indian and Finnish children and investigated the influence of FUT2 secretor status and birth mode on the gut microbiome of these populations. Using multiple profiling techniques, we show that the gut bacterial community structure in 13–14-year-old Indian (n = 47) and Finnish (n = 52) children differs significantly. Specifically, Finnish children possessed higher Blautia and Bifidobacterium, while genera Prevotella and Megasphaera were predominant in Indian children. Our study also demonstrates a strong influence of FUT2 and birth mode variants on specific gut bacterial taxa, influence of which was noticed to differ between the two populations under study.

Nitrincola alkalisediminis sp. nov., an alkaliphilic bacterium isolated from an alkaline lake

Two Gram-stain-negative, aerobic, alkaliphilic bacteria (strains MEB087T and MEB142) were isolated from sediment and water samples, respectively, collected from the alkaline Lonar Lake in Maharashtra, India. Strains MEB087T and MEB142 shared 99.8 % 16S rRNA gene sequence similarity and were 85 % related on the basis of DNA-DNA hybridization. The 16S rRNA gene sequences of both strains showed close relationship with the genus Nitrincola, and their closest neighbour was Nitrincola lacisaponensis 4CAT with 97.7 % sequence similarity. MEB087T and MEB142 exhibited only 45 % and 54 % DNA-DNA relatedness, respectively, with Nitrincola lacisaponensis DSM 16316T. Both strains were asporogenous, short, non-motile rods capable of utilizing a limited range of organic acids as sole carbon and energy sources. They were oxidase- and catalase-positive, able to reduce nitrate and nitrite; but unable to degrade DNA, urea, gelatin, casein or starch. They grew optimally at pH 9.5 (tolerating up to pH 11) and could withstand up to 0.6 M NaCl. The predominant cellular fatty acids were summed feature 8 comprising C18 : 1ω7c/C18 : 1ω6c (47-49 %) followed by summed feature 3 comprising C16 : 1ω7c/C16 : 1ω6c (28-32 %). The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The DNA G+C content was 49.3-49.7 mol%. On the basis of the phylogenetic analysis and chemotaxonomic characteristics, strains MEB087T and MEB142 represent a novel species in the genus Nitrincola, for which the name Nitrincola alkalisediminis sp. nov. is proposed. The type strain is MEB087T ( = KCTC 42948T = JCM 19317T) with MEB142 ( = KCTC 42949 = JCM 19318) as an additional strain.

Insights into Diversity and Imputed Metabolic Potential of Bacterial Communities in the Continental Shelf of Agatti Island

Marine microbes play a key role and contribute largely to the global biogeochemical cycles. This study aims to explore microbial diversity from one such ecological hotspot, the continental shelf of Agatti Island. Sediment samples from various depths of the continental shelf were analyzed for bacterial diversity using deep sequencing technology along with the culturable approach. Additionally, imputed metagenomic approach was carried out to understand the functional aspects of microbial community especially for microbial genes important in nutrient uptake, survival and biogeochemical cycling in the marine environment. Using culturable approach, 28 bacterial strains representing 9 genera were isolated from various depths of continental shelf. The microbial community structure throughout the samples was dominated by phylum Proteobacteria and harbored various bacterioplanktons as well. Significant differences were observed in bacterial diversity within a short region of the continental shelf (1–40 meters) i.e. between upper continental shelf samples (UCS) with lesser depths (i.e. 1–20 meters) and lower continental shelf samples (LCS) with greater depths (i.e. 25–40 meters). By using imputed metagenomic approach, this study also discusses several adaptive mechanisms which enable microbes to survive in nutritionally deprived conditions, and also help to understand the influence of nutrition availability on bacterial diversity.