Enhanced Detoxification of Arsenic Under Carbon Starvation: A New Insight into Microbial Arsenic Physiology.

Nutrient availability in nature influenced the microbial ecology and behavior present in existing environment. In this study, we have focused on isolation of arsenic-oxidizing cultures from arsenic devoid environment and studied effect of carbon starvation on rate of arsenite oxidation. In spite of the absence of arsenic, a total of 40 heterotrophic, aerobic, arsenic-transforming bacterial strains representing 18 different genera were identified. Nineteen bacterial species were isolated from tannery effluent and twenty-one from tannery soil. A strong co-relation between the carbon starvation and arsenic oxidation potential of the isolates obtained from the said niche was observed. Interestingly, low carbon content enhanced the arsenic oxidation ability of the strains across different genera in Proteobacteria obtained. This represents the impact of physiological response of carbon metabolism under metal stress conditions. Enhanced arsenic-oxidizing ability of the strains was validated by the presence of aio gene and RT-PCR, where 0.5- to 26-fold up-regulation of arsenite oxidase gene in different genera was observed. The cultures isolated from tannery environment in this study show predominantly arsenic oxidation ability. This detoxification of arsenic in lack of carbon content can aid in effective in situ arsenic bioremediation.

Enterobacillus tribolii gen. nov., sp. nov., a novel member of the family Enterobacteriaceae, isolated from the gut of a red flour beetle, Tribolium castaneum.

Two novel Gram-stain negative facultative anaerobic, motile, rod-shaped bacterial strains IG-V01(T) and IG-V01b were isolated from the gut of red flour beetles, Tribolium castaneum. The 16S rRNA gene sequences of strains IG-V01(T) and IG-V01b were found to have their highest sequence similarity (96.5% and 96.4%) with Serratia nematodiphila DZ0503SBS1(T) (Enterobacteriaceae family) respectively. Strains IG-V01(T) and IG-V01b share 100% 16S rRNA gene sequence similarity and exhibit very similar phenotypic characteristics. In addition, they show 89.7% genomic relatedness (DNA-DNA hybridisation). Major fatty acids were identified to be C(16:0) (38.3%), C(17:0) cyclo (19.5-20%) and C(14:0) (11.2-11.3%). Cells contain phosphatidylethanolamine and diphosphatidylglycerol as predominant polar lipids. Genomic DNA G+C content (mol%) was determined to be 51.5-51.7. A polyphasic approach employing the study of morphological, physiological, chemotaxonomic, genomic and phylogenetic analysis revealed that the two newly isolated strains cannot be placed in any of the existing genera of the family Enterobacteriaceae. Therefore, it is proposed that strains IG-V01(T) and IG-V01b belong to a novel genus within the family Enterobacteriaceae, and represent a new species Enterobacillus tribolii gen. nov., sp. nov., with the type strain =IG-V01(T) = KCTC 42159(T) = MCC 2532(T).

Distribution and evolutionary impact of wolbachia on butterfly hosts.

Wolbachia are maternally inherited endosymbiotic alpha-proteobacteria found in terrestrial arthropods and filarial nematodes. They are transmitted vertically through host cytoplasm and alter host biology by inducing various reproductive alterations, like feminization, parthenogenesis, male killing (MK) and cytoplasmic incompatibility. In butterflies, some effects especially MK and sperm-egg incompatibility are well established. All these effects skew the sex ratio towards female and subsequently favor the vertical transmission of Wolbachia. Some of the insects are also infected with multiple Wolbachia strains which may results in some complex phenomenon. In the present review the potential of Wolbachia for promoting evolutionary changes in its hosts with emphasis on recent advances in interactions of butterfly-Wolbachia is discussed. In addition to this, strain diversity of Wolbachia and its effects on various butterfly hosts are also highlighted.

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

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).