BackgroundMicrobiota inhabiting midguts of mosquitoes play a key role in the host - parasite interaction and enhance vectorial capacity of viral diseases like dengue and chikungunya fevers. Mosquito midgut is considered to be an important site for host-pathogen interaction and pathogen survival is thought to be an outcome of this interaction. In the present study we examined the bacterial community in the midgut of Aedes mosquitoes in Arunanchal Pradesh, India, a subtropical zone where dengue fever is reported to be emerging.MethodLarvae and pupa of Aedes mosquitoes were collected from a biodiversity hotspot, Bhalukpong, Arunachal Pradesh, India. 16S rRNA gene sequences were used for identification of isolated bacterial population from each species of mosquitoes. We used various diversity indices to assess the diversity and richness of the bacterial isolates in both mosquito species.ResultOn the basis of 16S rRNA gene sequence analysis a total of 24 bacterial species from 13 genera were identified belonging to 10 families of four major phyla. Phylum Proteobacteria was dominant followed by Firmicutes, Bacteroidetes and Actinobacteria. The midgut bacteria belonging to the phylum Proteobacteria and Firmicutes were isolated from both Ae. albopictus and Ae. aegypti, whereas, bacteria belonging to phylum Bacteroidetes and Actinobacteria were isolated only from Ae. albopictus and Ae. aegypti respectively. Enterobacter cloacae was the dominant bacterial species in both Ae. albopictus (33.65 %) and Ae. aegypti (56.45 %). Bacillus aryabhattai (22.78 %) was the second most common bacterial species in Ae. albopictus whereas, in Ae. aegypti the second most common bacterial species was Stenotrophomonas maltophilia (7.44 %).ConclusionThe family Enterobacteriaceae of phylum Proteobacteria was dominant in both species of Aedes mosquitoes. To the best of our knowledge, this is the first attempt to study midgut microbiota from a biodiversity hotspot in Northeastern India. Some bacterial genera Enterobacter and Acinetobacter isolated in this study are known to play important roles in parasite-vector interaction. Information on midgut microflora may lead towards the development of novel, safe, and effective strategies to manipulate the vectorial capacity of mosquitoes.

Aedes aegypti and Ae. albopictus are among the most important vectors of arboviral diseases, worldwide. Recent studies indicate that diverse midgut microbiota of mosquitoes significantly affect development, digestion, metabolism, and immunity of their hosts. Midgut microbiota has also been suggested to modulate the competency of mosquitoes to transmit arboviruses, malaria parasites etc. Interestingly, the midgut microbial flora is dynamic and the diversity changes with the development of vectors, in addition to other factors such as species, sex, life-stage, feeding behavior and geographical origin. The aim of the present study was to investigate the midgut bacterial diversity among larva, adult male, sugar fed female and blood fed female Ae. albopictus collected from Tezpur, Northeastern India. Based on colony morphological characteristics, we selected 113 cultivable bacterial isolates for 16S rRNA gene sequence based molecular identification. Of the 113 isolates, we could identify 35 bacterial species belonging to 18 distinct genera under four major phyla, namely Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Phyla Proteobacteria and Firmicutes accounted for majority (80%) of the species, while phylum Actinobacteria constituted 17% of the species. Bacteroidetes was the least represented phylum, characterized by a single species- Chryseobacterium rhizoplanae, isolated from blood fed individuals. Dissection of midgut microbiota diversity at different developmental stages of Ae. albopictus will be helpful in better understanding mosquito-borne diseases, and for designing effective strategies to manage mosquito-borne diseases.

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Elicitation of cell suspension cultures of Capsicum assamicum (Bhut Jolokia) for enhancement of capsaicin content was tried using different elicitors such as cellulase, vanillin, methyl jasmonate, salicylic acid and sinapic acid in different concentrations for 24, 48 and 72 hours. Cell suspension culture was established in B5 media supplemented with 3.5 mM 2,4-D (2,4-diphenoxyacetic acid) and 1.1 mM Kin and elicitors were introduced at the end of exponential phase. All the elicitors, except methyl jasmonate, led to significant increase in production of capsaicin. Sinapic acid, when added in 22 µM concentration and incubated for 24 hours, led to highest capsaicin accumulation of 0.5% (5068 µg/g) which was highest among all the treatments.

Bhut Jolokia (Capsicum assamicum), one of the hottest chilli in the world is a chilli cultivar, endemic to North East India and is extensively cultivated in the states of Assam, Nagaland and Manipur. The demand of this chilli is very high in domestic as well as in the international market due to its extreme hotness and pleasant aroma. This plant is severely affected by leaf curl disease caused by Begomovirus, leading to total crop loss. Accurate diagnosis of this viral disease at seedling stage, prior to transplanting, is essential to prevent further spread of the disease. With an aim to device a rapid and accurate detection assay, Rolling Circle Amplification (RCA)-Polymerase Chain Reac-tion (PCR) technique was used for detection of the viral pathogen. RCA tech-nique was employed to increase the viral template and PCR was conducted using a degenerate primer pair. With the help of this assay, 1.4 kbp segment of DNA-A genome of the Begomovirus was amplified. Phylogeny revealed close proximity of the isolate with Tomato leaf curl Bangladesh virus. This is the first report on characterization of Begomovirus infecting Bhut Jolokia in Tezpur region of Assam.

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Aedes mosquitoes are responsible for the transmission of arboviruses including dengue, chikungunya, zika, and yellow fever throughout the world. Mosquito gut harbors a variety of microbes, known to play a potential role in various physiological processes such as food digestion and pathogen development. Many bacterial species exert various movements like swarming, gliding and twitching which vary with individual bacterial species. Swarming is one of the movement patterns of bacterial cells in which newly growing cells direct themselves towards the edges of the colony on the solid agar plate. We have isolated a bacterial colony, which exerts swarming activity and moves away from its inoculation point following a translucent path. After repeated sub-culturing of the colony we isolated two different bacterial species which were found to be highly associated to each other in co-culture. Various techniques like biochemical analysis, 16S rRNA gene sequence based analysis, MALDI-TOFF MS and Scanning Electron Microscopy (SEM) were applied for in-depth characterization of isolates. The isolates were identified as Staphylococcus saprophyticus and Brevibacillus agri. Both bacterial isolates showed swarming activity in co-culture on the solid agar surface, but lost the activity when tested individually. Moreover, the swarming activity was even not recovered when both purified bacterial isolates were mixed at different concentrations. This demonstrated that an integral connection exists between the two species which is responsible for their swarming activity in co-culture.

Toxigenic cyanobacterial blooms in the water bodies represent a major ecological problem around the world. Some species produces a diverse range of toxins that have hepatotoxic, neurotoxic, cytotoxic and dermatoxic activity and hence have deleterious effect on humans, animals and fishes leading to death as well. Cultural eutrophication of water bodies leads to increased incidence of these harmful cyanobacterial blooms worldwide. North-East India being a biodiversity hotspot harbor many species of cyanobacteria. Few reports suggested presence of few toxigenic cyanobacteria in the water bodies of Assam, but no systematic studies have been undertaken to evaluate their toxicity. This work is being conducted to gather information on major toxigenic cyanobacteria, with special emphasis to microcystin (a cyclic heptapeptides with high acute and chronic toxicities to humans and animals) producing strains. Water samples have been collected from few water bodies of North-East and enriched in specific media. The toxin Microcystin was detected using specific ELISA kit and positive results have been obtained. Further, 16s rDNA sequencing was employed for molecular identification of the strains.