Cross-Infectivity of Ralstonia solanacearum from Marigold Grown in Andaman Islands

Bacterial wilt disease, caused by Ralstonia solanacearum, is one of the major concerns for marigold cultivation in Andaman Islands. Cross-infectivity potential of the bacterial wilt pathogen, isolated from marigold, was tested in other common vegetable-hosts of the Island. Pathogen identity was confirmed by morphological identification and Biolog based phenotypic fingerprinting. Cross-infectivity tests revealed tomato to be the most susceptible among the three solanaceous hosts tested. Highest wilt incidence was observed in tomato and marigold (100%) plants, followed by 55.6% in brinjal and 22.3% in chilli, upon artificial soil inoculation. Our study enlightens pathogenic potential of the bacterial wilt pathogen in important vegetable crops of Andaman Islands and can help formulate suitable management practices for successful management of the pathogen

Bioactive potential of selected actinobacterial strains against Mycobacterium tuberculosis and other clinical pathogens

1307-1311Marine actinobacteria produces diverse array of metabolites with novel chemical structures with potential bioactivities. Exploring the understudied ecosystems may increase the chance of getting novel actinobacteria and new metabolites.The present study explores the bioactive potential of actinobacteria isolated from the marine ecosystem of Andaman and Nicobar Islands, Bay of Bengal, against Mycobacterium tuberculosis and other clinical pathogens. The crude extracts from 15 marine actinobacterial strains were produced through agar surface fermentation using YEME agar and extracted using ethyl acetate. The crude extracts were tested against the standard strain M. tuberculosis H37Rv, clinical drug sensitive M. tuberculosis, and MDR M. tuberculosis strains by luciferase reporter phage (LRP) assay at 500 µg/ml concentration. The anti-microbial activity against other clinical pathogens, namely, Staphylococcus aureus, Escherichia coli, Salmonella paratyphi, Klebsiellapneumoniae, Pseudomonas aeruginosa, Candida albicans, and Cryptococcusneoformans and non-tubercular mycobacteria, M. smegmatis was studied by agar plug method. Among the 15 extracts that were tested for anti-tubercular activity, the crude ethyl acetate extract of the 14 actinobacterial strains showed anti-tubercular activity against at least one of the three M. tuberculosis strains. Exceptionally, the ethyl acetate extract of strain SACC 168 inhibited all three M. tuberculosis strains tested. In anti-microbial screening, the crude extracts of eight strains showed anti-microbial activity including six strains, which were active against the non-tuberculous mycobacteria. Further purification and characterization of the active molecule from the potential extracts will pave way for the potential natural product candidate for tuberculosis and other microbial infections

Antibacterial and anti-HIV activity of extracellular pigment from Streptomyces sp. S45 isolated from Sabarimala forest soil, India

861-868Actinobacteria, particularly from under-studied habitats, are often endowed with diverse biological properties. In the present study, about 17 actinobacterial strains were isolated from Sabarimala forest — an understudied ecosystem in Western Ghats, India and screened for their pigment producing potential. Pinkish brown soluble pigment producing Streptomyces sp. strain S45 was selected and screened for antibacterial and anti-HIV activity. The bioactivity of ethyl acetate extract of the strain S45 showed maximum zone of inhibition against Staphylococcus aureus ATCC 29213 (17.3±0.4 mm) and Bacillus cereus (15.6±0.6 mm). Also, it showed anti-HIV activity with the IC50 value of 8.75 µg/mL. The bioactive pigment isolated from the strain S45 was partially purified and characterized using UV absorption. In bio-autography, an antibacterial compound found to be active against S. aureus ATCC 29213 and its MIC values ranged between 25-1.56 µg/mL. Variables such as glucose, rhamnose, soybean meal and CaCl2, pH 7 and temperature 30℃ were found to influence bioactive pigment production. Potential strain S45 was identified as Streptomyces species on the basis of microscopic, cultural, physiological and 16SrRNA analysis. Results suggest that the Streptomyces sp. S45 strain explored in this study could be a promising candidate for isolation of antibacterial and anti HIV pigment

Antibacterial and anti-HIV activity of extracellular pigment from Streptomyces sp. S45 isolated from Sabarimala forest soil, India

Actinobacteria, particularly from under-studied habitats, are often endowed with diverse biological properties. In the present study, about 17 actinobacterial strains were isolated from Sabarimala forest an understudied ecosystem in Western Ghats, India and screened for their pigment producing potential. Pinkish brown soluble pigment producing Streptomyces sp. strain S45 was selected and screened for antibacterial and anti-HIV activity. The bioactivity of ethyl acetate extract of the strain S45 showed maximum zone of inhibition against Staphylococcus aureus ATCC 29213 (17.3±0.4 mm) and Bacillus cereus (15.6±0.6 mm). Also, it showed anti-HIV activity with the IC50 value of 8.75 µg/mL. The bioactive pigment isolated from the strain S45 was partially purified and characterized using UV absorption. In bio-autography, an antibacterial compound found to be active against S. aureus ATCC 29213 and its MIC values ranged between 25-1.56 µg/mL. Variables such as glucose, rhamnose, soybean meal and CaCl2, pH 7 and temperature 30℃ were found to influence bioactive pigment production. Potential strain S45 was identified as Streptomyces species on the basis of microscopic, cultural, physiological and 16SrRNA analysis. Results suggest that the Streptomyces sp. S45 strain explored in this study could be a promising candidate for isolation of antibacterial and anti HIV pigment

<em>Bacillus </em>spp. for suppression of eggplant bacterial wilt pathogen in Andaman Islands: Isolation and characterization

131-137Bacillus spp. isolated from different soils of Andaman Islands was characterized for antimicrobial potential by different methods. Among 65 strains tested, six Bacillus strains showed best in vitro antagonistic potential against solanaceous bacterial wilt pathogen Ralstonia solanacearum. The identity of the Bacillus strains were confirmed using 16S rRNA gene sequencing and biolog based phenotypic fingerprinting. The functional analysis revealed that most of the strains were positive for the production of IAA, siderophore and phosphate solubilization. In glass house and field studies, Bacillus amyloliquifaceans strain (Bs_Abi) showed significant biocontrol efficacy (92.1 and 73.7%, respectively) against brinjal bacterial wilt disease. The antimicrobial potential of Bs_Abi were further ascertained by presence of nine antimicrobial peptide (AMP) gene biosynthesis in PCR amplifications which confirmed the presence of peptide genes for six antibiotics (iturin, bacillomycin D, mycosubtilin, surfactin, bacilysin and subtilin). Our study revealed that the utilization of such antagonistic Bacillus spp. with multi antimicrobial peptide genes and more functional traits from tropical/ extreme soils would play a vital role in management of eggplant bacterial wilt disease and in formulation of new bioinoculants for improving the cropping system in Andaman and Nicobar Islands

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Not AvailableSolanaceous vegetables like brinjal, tomato and chilli occupy a sizeable area in vegetable cultivation in Andaman and Nicobar Islands. But the bacterial wilt disease caused by Ralstonia solanacearum is the severe constraint for growing solanaceous vegetables.Not Availabl