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The gut microbial community structure of adult Thrips tabaci collected from 10 different agro-climatically diverse locations of India was characterized by using the Illumina MiSeq platform to amplify the V3 region of the 16S rRNA gene of bacteria present in the sampled insects. Analyses were performed to study the bacterial communities associated with Thrips tabaci in India. The complete bacterial metagenome of T. tabaci was comprised of 1662 OTUs of which 62.25% belong to known and 37.7% of unidentified/unknown bacteria. These OTUs constituted 21 bacterial phyla of 276 identified genera. Phylum Proteobacteria was predominant, followed by Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Additionally, the occurrence of the reproductive endosymbiont, Wolbachia was detected at two locations (0.56%) of the total known OTUs. There is high variation in diversity and species richness among the different locations. Alpha-diversity metrics indicated the higher gut bacterial diversity at Bangalore and lowest at Rahuri whereas higher bacterial species richness at T. tabaci samples from Imphal and lowest at Jhalawar. Beta diversity analyses comparing bacterial communities between the samples showed distinct differences in bacterial community composition of T. tabaci samples from different locations. This paper also constitutes the first record of detailed bacterial communities associated with T. tabaci. The location-wise variation in microbial metagenome profile of T. tabaci suggests that bacterial diversity might be governed by its population genetic structure, environment and habitat., Competing Interests: The authors have declared that no competing interests exist.

Ballast tank biofilms pose an additional risk of microbial invasion if sloughed off during ballasting operations, yet their significance and invasion biology is poorly understood. In this study, biofilms developed in marine and freshwater locations were exposed to prolonged darkness and aging by mimicking ballast water conditions in the laboratory. Upon prolonged darkness, the decay of phytoplankton, as indicated by the decrease in chlorophyll a in marine biofilms, led to remineralization and enhanced bacterial and protist populations. However, the same trend was not observed in the case of freshwater biofilms wherein the microbial parameters (i.e., bacteria, protists) and chlorophyll a decreased drastically. The bacterial community structure in such conditions was evaluated by real-time quantitative PCR (qPCR), and results showed that the biofilm bacterial communities changed significantly over a period of time. α-Proteobacteria was the most stable taxonomic group in the marine biofilms under dark conditions. However, β-proteobacteria dominated the freshwater biofilms and seemed to play an important role in organic matter remineralization. γ-Proteobacteria, which includes most of the pathogenic genera, were affected significantly and decreased in both the types of biofilms. This study revealed that marine biofilm communities were able to adapt better to the dark conditions while freshwater biofilm communities collapsed. Adaptation of tolerant bacterial communities, regeneration of nutrients via cell lysis, and presence of grazers appeared to be key factors for survival upon prolonged darkness. However, the fate of biofilm communities upon discharge in the new environment and their invasion potential is an important topic for future investigation.

To appreciate differences in benthic bacterial community composition at the relatively pristine Tuvem and the anthropogenically-influenced Divar mangrove ecosystems in Goa, India, parallel tag sequencing of the V6 region of 16S rDNA was carried out. We hypothesize that availability of extraneously-derived anthropogenic substrates could act as a stimulatant but not a deterrent to promote higher bacterial diversity at Divar. Our observations revealed that the phylum Proteobacteria was dominant at both locations comprising 43-46% of total tags. The Tuvem ecosystem was characterized by an abundance of members belonging to the class Deltaproteobacteria (21%), ~ 2100 phylotypes and 1561 operational taxonomic units (OTUs) sharing > 97% similarity. At Divar, the Gammaproteobacteria were ~ 2× higher (17%) than at Tuvem. A more diverse bacterial community with > 3300 phylotypes and > 2000 OTUs mostly belonging to Gammaproteobacteria and a significantly higher DNT (n = 9, p < 0.001, df = 1) were recorded at Divar. These findings suggest that the quantity and quality of pollutants at Divar are perhaps still at a level to maintain high diversity. Using this technique we could show higher diversity at Divar with the possibility of Gammaproteobacteria contributing to modulating excess nitrate.

The present investigation uncovers various pieces of evidence for the possible biologically induced mineralization in iron mats associated with a pH-neutral spring in the Borra caves, Vishakhapatnam, India. Electron microscopy [scanning electron microscopy (SEM) and transmission electron microscopy (TEM)] demonstrated large numbers of (i) hollow tubes (diameter ∼1 μm) resembling sheaths of the iron-oxidizing bacteria Leptothrix, (ii) thin (diameter <<1 μm) solid fibers of uncertain origin, (iii) nanoscale subspherical to irregularly shaped particles encrusting tubes and fibers, and (iv) aggregates of broken and partially disintegrated sheaths, fibers, and particles embedded in extracellular polymeric substances (EPS) occasionally including microbial cells. X-ray microanalyses by energy dispersive spectroscopy (EDS) revealed that the mat accumulated largely Fe but also smaller amounts of Si and traces of P and Ca. Particles rich in Si and Al (possibly kaolinite) and Ca (carbonate) were also observed. High-resolution TEM/EDS of unstained ultrathin sections suggests that microbial sheaths were highly mineralized by amorphous to cryptocrystalline Fe-rich phases and less frequently by other fine-grained and fibrous authigenic claylike minerals. Total number of microorganisms in the iron mats was 5.8×10(5) cells, g sed(-1) (wet weight). Analysis of the 16S rRNA gene diversity revealed microorganisms assigned to eight different phyla [Proteobacteria (62%), Chloroflexi (8%), Bacteroidetes (7%), Planctomycetes (1%), Actinobacteria (5%), Acidobacteria (6%), Nitrospira (1%), Firmicutes (5%)]. Within the Proteobacteria, Betaproteobacteria was the predominant class, which accounted for 28% of the sequences. Within this class some obvious similarities between the obtained sequences and sequences from other cave systems could be seen, especially sequences affiliated with Leptothrix, Siderooxidans, Crenothrix, Comamonadaceae, Dechloromonas, and many uncultured Betaproteobacteria. Four (4%) of the sequences could not be assigned to phylum level but were affiliating with the candidate division TM7 (2%), candidate division OP11 (1%), and candidate division WWE3 (1%). The results allow us to infer a possible relationship of microbial sheaths, EPS, and the iron precipitates to microbial community diversity in the Borra cave springs. Understanding biogenic iron oxides in caves has important astrobiological applications as it provides a potential tool for the detection of extraterrestrial life.

An ovoid-rod-shaped, phototrophic, purple non-sulfur bacterium, designated strain JA322(T), was isolated in pure culture from a water sample collected from a saline pond with purple-coloured water, located near Satpada in Orissa, India. Strain JA322(T) was Gram-negative and non-motile and grew photoheterotrophically with a number of organic compounds serving as carbon sources or electron donors. Intracellular photosynthetic membranes were of the vesicular type. Bacteriochlorophyll a and carotenoids of the spheroidene series were present as photosynthetic pigments. Biotin and thiamine were required for growth of strain JA322(T). Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA322(T) was related most closely to the type strains of Rhodovulum euryhalinum (95.8 % similarity) and Rhodovulum strictum (94.8 %) and clustered with species of the genus Rhodovulum of the family Rhodobacteraceae. On the basis of phenotypic and molecular genetic evidence, it is suggested that strain JA322(T) represents a novel species of the genus Rhodovulum, for which the name Rhodovulum lacipunicei sp. nov. is proposed. The type strain is JA322(T) (=NBRC 104147(T)=KCTC 5700(T)).

The prokaryotic diversity associated with an Indian soda lake (Lonar Crater Lake) located in a basaltic soil area was investigated using a culture-independent approach. Community DNA was extracted directly from four sediment samples obtained by coring to depths of 10-20 cm. Small subunit rRNA genes (16S rDNA) were amplified by PCR using primers specific to the domains Bacteria and Archaea. The PCR products were cloned and sequenced. For the bacterial rDNA clone library, 500 clones were randomly selected for further analysis. After restriction fragment length polymorphism (RFLP) analysis and subsequent sequencing, a total of 44 unique phylotypes were obtained. These phylotypes spanned a wide range within the domain Bacteria, occupying eight major lineages/phyla. 34% of the clones were classified as firmicutes. The other clones were grouped into proteobacteria (29.5%), actinobacteria (6.8%), deinococcus-thermus (4.5%), cytophages-flavobacterium-bacteroidetes (13.3%), planctomycetes (6.8%), cyanobacteria (4.5%) and spirochetes (2.27%). In the case of the archaeal 16S rDNA library, analysis of 250 randomly selected clones revealed the presence of 13 distinct phylotypes; 5 phylotypes were associated with Crenarchaeota and 8 with Euryarchaeota. Most of the euryarchaeota sequences were related to methanogens. Findings from this molecular study of a site investigated for the first time have revealed the presence of a highly diverse bacterial population and a comparatively less diverse archaeal population. The majority ( approximately 80%) of the cloned sequences show little affiliation with known taxa (<97% sequence similarity) and may represent novel taxa/sequences and organisms specifically adapted to this basaltic soda lake environment. Diversity analyses demonstrate greater diversity and evenness of bacterial species compared to a skewed representation of species for Archaea.

The bacterial strain SJT(T), along with 15 other mesophilic, neutrophilic and facultatively sulfur-oxidizing chemolithotrophic isolates, was isolated by enrichment on reduced sulfur compounds as the sole energy and electron source from soils immediately adjacent to the roots of Clitoria ternatea, a slender leguminous herb of the Lower Gangetic plains of India. Strain SJT(T) was able to oxidize thiosulfate and elemental sulfur for chemolithoautotrophic growth. 16S rRNA and recA gene sequence-based phylogenetic analyses showed that the Gram-negative rod-shaped bacterium belonged to the genus Mesorhizobium and was most closely related to Mesorhizobium loti, Mesorhizobium plurifarium, Mesorhizobium amorphae and Mesorhizobium chacoense. Unequivocally low 16S rRNA (<97 %) and recA (< or =88 %) gene sequence similarities to all existing species of the most closely related genera, a unique fatty acid profile, a distinct G+C content (59.6 mol%) and phenotypic characteristics all suggested that strain SJT(T) represents a novel species. DNA-DNA hybridization and SDS-PAGE analysis of whole-cell proteins also confirmed the taxonomic uniqueness of SJT(T). It is therefore proposed that isolate SJT(T) (= LMG 22697T = MTCC 7001T) be classified as the type strain of a novel species, Mesorhizobium thiogangeticum sp. nov.