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 less than 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.

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With increasing number of novel bacteria being isolated from the human gut ecosystem, there is a greater need to study their role in the gut ecosystem and their effect on the host health. In the present study, we carried out in silico genome-wide analysis of two novel Megasphaera sp. isolates NM10 (DSM25563) and BL7 (DSM25562), isolated from feces of two healthy individuals and validated the key features by in vitro studies. The analysis revealed the general metabolic potential, adaptive features and the potential effects of these isolates on the host. The comparative genome analysis of the two human gut isolates NM10 and BL7 with ruminal isolate Megasphaera elsdenii (DSM20460) highlighted the differential adaptive features for their survival in human gut. The key findings include features like bile resistance, presence of various sensory and regulatory systems, stress response systems, membrane transporters and resistance to antibiotics. Comparison of the “glycobiome” based on the genomes of the ruminal isolate with the human gut isolates NM10 and BL revealed the presence of diverse and unique sets of Carbohydrate-Active enzymes (CAZymes) amongst these isolates, with a higher collection of CAZymes in the human gut isolates. This could be attributed to the difference in host diet and thereby the environment, consequently suggesting host specific adaptation in these isolates. In silico analysis of metabolic potential predicted the ability of these isolates to produce important metabolites like short chain fatty acids (butyrate, acetate, formate, and caproate), vitamins and essential amino acids, which was further validated by in vitro experiments. The ability of these isolates to produce important metabolites advocates for a potential healthy influence on the host. Further in vivo studies including transcriptomic and proteomic analysis will be required for better understanding the role and impact of these Megasphaera sp. isolates NM10 and BL7 on the human host.

An extended incubation strategy to culture slow growing members of anaerobic fungi resulted in the isolation of a novel anaerobic fungus from the rumen of a goat after 15 days. The novel genus, represented by type strain G1SC, showed filamentous monocentric thallus development and produced uniflagellate zoospores, hence, showing morphological similarity to the genera Piromyces, Buwchfawromyces, Oontomyces and Pecoramyces. However, strain G1SC showed genetic similarity to the genus Anaeromyces, which, though produces uniflagellate zoospore, also exhibits polycentric thallus development. Moreover, unlike Anaeromyces, strain G1SC did not show hyphal constrictions, instead produced a branched, determinate and anucleate rhizoidal system. This fungus also displayed extensive sporangial variations, both exogenous and endogenous type of development, short and long sporangiophores and produced septate sporangia. G1SC utilised various complex and simple substrates, including rice straw and wheat straw and produced H2, CO2, formate, acetate, lactate, succinate and ethanol. Phylogenetic analysis, using internal transcribed spacer 1 (ITS1) and D1/D2 domain of large-subunit (LSU) rRNA locus, clearly showed a separate lineage for this strain, near Anaeromyces. The ITS1 based geographical distribution studies indicated detection of environmental sequences similar (93–96%) to this strain from cattle faeces. Based on morphological and molecular characterisation results of strain G1SC, we propose a novel anaerobic fungus Liebetanzomycespolymorphusgen. et sp. nov., in the phylum Neocallimastigomycota.

Chickpea pod borer, Helicoverpa armigera, displays resistance to chemical insecticides and transgenics. The potential nontransformative RNAi approach of specific gene silencing by mRNA breakdown through exogenous double-stranded (dsRNA) delivery to Helicoverpa faces problems of degradation by nucleases and insect gut pH. We demonstrate that chitosan nanoparticles (CNPs) effectively mediate specific dsRNA delivery against Helicoverpa armigera juvenile hormone methyltransferase (JHAMT) and acetylcholine esterase (ACHE) target genes. Ionotropically synthesized cationic CNPs (100 nm size, +32 mV charge) loaded dsRNA efficiently and protected it effectively from degradation by nucleases and insect gut pH. Tagging CNPs with Calcofluor fluorescence illustrated its efficient uptake in columnar insect gut cells. The potential of CNPs-mediated dsRNA delivery was elucidated with effective silencing of green fluorescent protein transformed Sf9 cells. Furthermore, CNPs–dsRNA complexes were stable for 5 d on leaf surfaces, and their ingestion with leaf effectively silenced H. armigera JHAMT and ACHE genes to suppress related enzyme activities and caused 100% insect mortality. Further, in planta bioassay with CNPs–dsRNA spray confirmed the RNAi induced insect mortality. Moreover, CNPs–dsRNA fed nontarget insects Spodoptera litura and Drosophila melanogaster were unaffected, and no toxicity was observed for CNPs in cell line studies. Remarkably, only two low dose (0.028 g/ha) topical CNPs-ache-dsRNA sprays on chickpea displayed reduced pod damage with high yields on par with chemical control in the field, which was followed by CNPs-jhamt-dsRNA nanoformulation. These studies can pave the way for the development of topical application of CNPs–dsRNA spray as a safe, specific, innovative insecticide for sustainable crop protection.