The present study reveals the production of dark, extracellular melanin pigment (386 mg/L) on peptone yeast extract iron agar medium by Streptomyces puniceus RHPR9 using the gravimetric method. UV-Visible, Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (1H) (NMR) spectroscopy confirmed the presence of melanin. Extracted melanin showed antibacterial activity against human pathogens such as Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli except for Klebsiella pneumoniae. A potent free radical scavenging activity was observed at 100 μg/mL of melanin by the DPPH method with a concentration of 89.01±0.05% compared with ascorbic acid 96.16±0.01%. Antitumor activity of melanin was evaluated by MTT assay against HEK 293, HeLa, and SK-MEL-28 cell lines with IC50 values of 64.11±0.00, 14.43±0.02, and 13.31±0.01 μg/mL respectively. Melanin showed maximum anti-inflammatory activity with human red blood cells (hRBC) (78.63 ± 0.01%) and minimum hemolysis of 21.37±0.2%. The wound healing potential of the pigment was confirmed on HeLa cells, cell migration was calculated, and it was observed that cell migration efficiency decreased with an increase in the concentration of melanin. To our knowledge, this is the first evidence of melanin produced from S. puniceus RHPR9 that exhibited profound scavenging, anti-inflammatory and cytotoxic activities.
Chilli is an important commercial crop and is consumed as spice as well as vegetable. Colletotrichum capsici is an important fungal pathogen causing anthracnose in chilli. The objective of the present study was to determine inhibitory activity against C. capsici of extracts of three foliose macrolichen species of the genus Parmotrema viz., P. tinctorum, P. grayanum and P. praesorediosum from Western Ghats of Karnataka, India. The antifungal effect was checked in terms of mycelial growth inhibition by Poisoned food technique. The spore suspension of C. capsici was inoculated on the centre of Potato dextrose agar plates (control and poisoned). The colony diameter of fungus in control and poisoned plates was recorded on 5 th day of incubation. The lichen extracts caused marked inhibition of test fungus as revealed by reduced colony diameter of test fungus in poisoned plates. Among lichens, P. tinctorum showed potent inhibitory activity and caused > 50 % of inhibition of test fungus. The lichens of the present study appeared promising as bio control agents against C. capsici.
Seven Bacillus spp. isolated from the marine water and the rhizosphere of the medicinal plant Coscinium fenestratum were studied to produce plant growth promotion (PGP) traits invitro. Among the seven isolates, MMRH22 and RHPR20 produced copious amounts of PGP traits. Based on the 16S rRNA sequence, the two potent bacterial isolates, RHPR20 and MMRH22, were identified as Bacillus mojavensis and Bacillus cereus, respectively. A compatibility test between the isolates RHPR20 and MMRH22 revealed they are compatible and can be used as a consortium. Both isolates were evaluated for the plant growth promotion and the biofortification of sorghum under greenhouse conditions. Treatments included the application of MMRH22, RHPR20, their consortium (RHPR20 + MMRH22), and an uninoculated control. Inoculation with bacterial cultures resulted in a significant increase in the plant height; the number of leaves; the leaf area; the root, shoot, and leaf weight; and the yield of sorghum at 30 and 60 days after sowing (DAS). The scanning electron micrograph of the sorghum plant roots revealed extensive colonization in the plants treated with the bacterial cultures compared to the uninoculated control. The sorghum grains obtained after final harvest were analyzed for their nutrient content by ICP–OES. The biofortification in sorghum grains was varied and was found to enhance the iron content up to 97%. This study revealed that treatments with microbial consortia enhance plant growth, yield, and iron content, which could combat nutrient deficiencies in plants and humans.
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.
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