Vandana Praveen

PRODUCTION OF ANTIBACTERIAL AND ANTIFUNGAL METABOLITES BY STREPTOMYCES VIOLACEUSNIGER AND MEDIA OPTIMIZATION STUDIES FOR THE MAXIMUM METABOLITE PRODUCTION

An antibiotic producing strain Streptomyces violaceusniger was isolated from soil sample, characterized and studied for antibacterial and antifungal activity profile. Fermentation broth and cell extracts were tested against typed test organisms. The activity profiles of the intracellular and extracellular crude extracts showed that the antibiotic producing culture produces two or more compounds, one being intracellular (antifungal), other being extracellular (antibacterial). Broth extract showed activity against E. coli, bacillus subtilis, B. cereus, Pseudomonas aeruginosa and Klebsiella pneumoniae. The cell extract showed activity against Candida albicans, Aspergillus niger, Trichoderma viridae, Fusarium moniliforme and Alternaria brassicicola. Production medium was optimized for antibiotic production.

Production of actinomycin-D by the mutant of a new isolate of Streptomyces sindenensis

An actinomycin-D producing strain was isolated from soil and characterized as Streptomyces sindenensis. The culture was subjected to UV irradiation and a mutant with 400% higher actinomycin-D production was isolated (400 mg/l-1 as compared to 80 mg/l-1 produced by the parent). Production medium was optimized and antibiotic yield with the mutant was enhanced to 850 mg/l-1 which is 963% higher as compared with the parent.

Phylogenetics of an antibiotic producing Streptomyces strain isolated from soil.

Traditional methods of species classification and identification of the organism are based on morphological, physiological, biochemical, developmental and nutritional characteristics. Accurate assignment of taxonomic status to the new biologically active microbial isolates through existing bioinformatics methods is now very essential and also helpful in chemical characterization of the active molecule produced by microorganisms. The bacterial strain M4 (ckm7) was isolated from the pre-treated soil sample collected from the agricultural field of Eastern Uttar Pradesh (U.P.), India and was found to be producing antibacterial and antifungal antibiotics. Taxonomic identification of the isolate belongs to the genus Streptomyces which was done with the help of sequence analysis and later confirmed by biological activity. Sequence comparison study of ckm7 showed 98% identical similarity with 16S rRNA gene sequences of Streptomyces spinichromogenes, Streptomyces triostinicus and Streptomyces capoamus. On the basis of both biological activity and phylogenetic analysis of ckm7, it was concluded that the isolated strain is a new variant of S. triostinicus.

Studies on medium optimization for the production of antifungal and antibacterial antibiotics from a bioactive soil actinomycete

A microbial isolate, characterized as Streptomyces sp. (MTCC 6819), produced antifungal metabolite intracellularly and antibacterial metabolite extracellularly under submerged fermentation conditions. This Gram-positive bacterium showed broad antimicrobial activity spectra against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) of partially purified (68.4%) antibacterial metabolite ranged between 50 and 12.5 μg/mL against multiple-drug-resistant bacteria. The producer organism exhibited strong activity against various yeast and fungi. The MIC values of the partially purified (70%) antifungal metabolite ranged between 6.25 and 3.125 μg/mL for unicellular fungi and 12.5 and 6.25 μg/mL for filamentous fungi. The conditions for the production of these bioactive agents were optimized and the effects of various nutritional factors were studied by classical and statistical methods.

Isolation, characterization and antifungal docking studies of wortmannin isolated from Penicillium radicum

During the search for a potent antifungal drug, a cell-permeable metabolite was isolated from a soil isolate taxonomically identified as Penicillium radicum. The strain was found to be a potent antifungal agent. Production conditions of the active compound were optimized and the active compound was isolated, purified, characterized and identified as a phosphoinositide 3-kinase (PI3K) inhibitor, commonly known as wortmannin (Wtmn). This is very first time we are reporting the production of Wtmn from P. radicum. In addition to its previously discovered anticancer properties, the broad spectrum antifungal property of Wtmn was re-confirmed using various fungal strains. Virtual screening was performed through molecular docking studies against potential antifungal targets, and it was found that Wtmn was predicted to impede the actions of these targets more efficiently than known antifungal compounds such as voriconazole and nikkomycin i.e. 1) mevalonate-5-diphosphate decarboxylase (1FI4), responsible for sterol/isoprenoid biosynthesis; 2) exocyst complex component SEC3 (3A58) where Rho- and phosphoinositide-dependent localization is present and 3) Kre2p/Mnt1p a Golgi alpha1,2-mannosyltransferase (1S4N) involved in the biosynthesis of yeast cell wall glycoproteins). We conclude that Wtmn produced from P. radicum is a promising lead compound which could be potentially used as an efficient antifungal drug in the near future after appropriate structural modifications to reduce toxicity and improve stability.

Production of actinomycin-D by a new isolate,Streptomyces sindenensis

An actinomycete strain, designated as C-5, was isolated from the soil sample collected from steel plant effluent sediment. The strain produced actinomycin-D in substantial quantities (80 mg/L). The strain C-5 was taxonomically characterised on the basis of morphological and phenotypic characteristics, genotypic data and phylogenetic analysis. A nearly complete 16S rRNA sequence of the isolate was determined and found to have 100% identity withStreptomyces sindenensis. Streptomyces sindenensis is not reported earlier to produce actinomycin-D. Anticancer activities were determined against various human cancer cell lines. Production of actinomycin-D was scaled up in bench scale fermentors and optimised to a titre of 120 mg/L.