Background:The Western ghats, the range of hills running along India's west coast, are well known for their rich and unique assemblage of flora and fauna. The present study was performed to evaluate the insecticidal potential of Actinomycetes isolated from the soils of the Western ghats of Agumbe, Karnataka. Methods: For isolation, the serially diluted soil sample was plated on Starch casein agar and incubated aerobically. The actinomycete isolates were identified by various parameters such as colony morphology, spore arrangement, staining, and biochemical reactions. The isolates were grown in Starch casein broth for seven days, the culture broth was extracted with butanol solvent and concentrated to get crude extract. Insecticidal activity of different concentrations of butanol extract of the isolates was determined against the second instar larvae of Aedes aegypti. The larvicidal effect, in terms of mortality of larvae, of the extracts was determined by counting the number of dead larvae after 24 hours. Results: Two actinomycete isolates were recovered from the soil sample and were identified as the species of Streptomyces on the basis of phenotypic, microscopic, biochemical, and staining characteristics. The colonies of the Streptomyces isolate 1 were creamish-white with yellow pigmentation and the spore arrangement was straight, whereas colonies of the Streptomyces isolate 2 were light grey with dark green pigmentation. The spore arrangement in isolate 2 was of the open loop type. Both the isolates were Gram-positive, non-acid fast, and caused hydrolysis of starch and casein. The insecticidal activity of different concentrations, namely 1.0, 2.5, and 5.0 mg/ml, of butanol extract of the Streptomyces isolates was tested against the second instar larvae of Aedes aegypti. The insecticidal potential of butanol extracts, in terms of larval mortality, was found to be dose dependent. Among the isolates, isolate 2 showed a marked insecticidal activity than isolate 1. At a concentration of 5 mg/ml, both the isolates caused 100% mortality of the larvae. At concentrations of 1 and 2.5 mg/ml, isolate 2 exhibited a stronger larvicidal activity than isolate 1. Conclusion: The insecticidal efficacy of the Streptomyces species might be due to the presence of active constituents in the extract. Isolation and characterization of active constituents from the butanol extract possessing insecticidal potential are to be investigated.

Forty two Streptomycetes isolates from soils of Kodachadri region in Western ghats were recovered by soil dilution technique. Cross streak method was followed for primary screening of antifungal activity. Positive isolates were subjected to secondary screening by cold extraction of fermentation broth in butanol solvent. Six isolates exhibited broad spectrum antifungal activity against all the tested yeast pathogens like Candida albicans, Candida lipolytica, Cryptococcus neoformens and Saccharomyces cerevisiae. One isolate showed excellent antifungal activity against all test organisms with maximum zone of inhibition 60 mm each incase of C. neoformens and C. albicans. Partial characterization of antifungal metabolite by TLC resulted in a purple spot with an R f value 0.50. The UV absorption spectra at 218 nm indicated possible chemical nature of the active metabolite as polyene group and purity was assessed by analytical HPLC.

Article Information Actinomycetes are among the industrially and therapeutically relevant microorganisms and are known to produce useful products such as antibiotics, enzymes, vitamins etc. Among actinomycetes, genus Streptomyces is known to produce a great array of products. In the present study, we have recovered a Streptomyces species RAMPP-065 from Western ghats soil of Kudremukh, Karnataka, India and determined its antimicrobial and antioxidant activity. The isolate was recovered on Starch casein agar and identified as Streptomyces species on the basis of cultural, microscopic, staining and biochemical characteristics. Fermentation was carried out in Starch casein broth for 7 days and filtered. The culture filtrate was extracted with ethyl acetate and the solvent was evaporated to get the extract. Antimicrobial activity of extract was tested against 8 bacteria and 2 fungi by agar well diffusion method. Gram positive bacteria were more sensitive to extract than Gram negative bacteria. Among fungi, susceptibility to extract was higher in Candida albicans than Cryptococcus neoformans. The extract showed a dose dependent scavenging of DPPH free radical as revealed by bleaching of DPPH radical color with increase in concentration of extract. In ferric reducing assay, the absorbance was found to increase with increase in extract concentration. Total phenolic content of extract, as estimated by Folin-Ciocalteau method, was 59mg Gallic acid equivalents/gram. The scavenging and reducing activity of extract were lesser when compared to reference compounds. The soils of Western ghats are rich sources for microorganisms with potent biological activities. To the best of our knowledge, this is the first report on bioactivity of Streptomyces species from Kudremukh soil. Further studies are to be carried out to characterize the Streptomyces isolate and the active principles present in the extract.

Article InformationThe present study is an attempt to isolate the fungi from the unexplored soils of Western Ghats and screen them for the production of some very important hydrolytic enzymes such as amylase, cellulose, CMCase, protease, lipase and pigment production. In this work, more than 200 fungal isolates were isolated from the forest soil were screened for the production of extracellular enzymes, identification of the screened isolates and secondary screening for amylase production was done. A total of 167 isolates were characterized, in them some up to species level. Aspergillus, Penicillium, Trichoderma and Cladosporium were predominated. A total of 14 isolates were selected for the secondary screening for amylase production. Aspergillus isolate 199 and Aspergillus isolate 43 produced more protein (169±07 and 160±04µg) respectively. Amylase assay also revealed greater activities (4.98±0.06 and 4.93± 0.07µ moles/ ml) in Aspergillus isolate 199 and Aspergillus isolate 43 respectively.

Article Information In the present study, characterization and antibacterial activity of a glycoside antibiotic from fermentation broth of bioactive Streptomyces variabilis PO-178 recovered previously from Western Ghat soil of Agumbe, Karnataka, India was investigated. Mass cultivation of the strain PO-178 was carried out in Starch casein nitrate broth. The fermentation broth was extracted using butanol solvent in a separation funnel. The concentrated butanol extract was subjected to chromatographic techniques viz., thin layer and silica gel column chromatography for purification of bioactive components. Out of 3 fractions (A, B and C) obtained, only one fraction (C) displayed inhibitory activity against Staphylococcus aureus and Pseudomonas aeruginosa. The bioactive fraction C was subjected to spectral analysis (LC-MS, IR, 1 H-NMR and 13 C-NMR) in order to determine the structure. On the basis result of spectral analysis, the purified fraction was predicted as a glycoside antibiotic with molecular weight 514 and molecular formula C24H34O12. The antibiotic displayed marked inhibitory activity against S. aureus as revealed by wider zones of inhibition and low minimum inhibitory concentration value.