Isolation, Characterization and Selection of Avermectin-Producing Streptomyces avermitilis Strains From Soil Samples

Abstract

Background:Streptomyces avermitilis, belonging to Actinomycetes, is specialized for production of avermectin, used as an anthelmintic and insecticidal agent. It is mostly found in soil and its isolation is very crucial for medically important avermectin production.Objectives:In the present study, 10 bacterial isolates lacking antimicrobial activities were isolated from the soil samples collected from different areas of Lahore, Pakistan.Materials and Methods:Three distinctive localities of Lahore were opted for soil assortment to isolate S. avermitilis. About 50 isolates of Streptomyces species were attained through selective prescreening procedures. All of these isolates were studied for production of the secondary metabolite, avermectin. Different test like soluble pigment color and melanin formation were used for identification. Biochemical characterizations of those isolates closely resembling the control in morphological characteristics, soluble pigment color and melanin formation tests were performed.Results:The 10 selected isolates were identified as the avermectin-producing strain by fermentation and characterized on ISP2 medium for aerial and reverse side mycelia color, soluble pigment color and melanin formation, in comparison with S. avermitilis DSM 41445. The best avermectin-producing isolate S1-C (10.15 mg/L) showed similar result as S. avermitilis DSM 41445, when subjected for culture characteristics analysis in different media along with biochemical characterization.Conclusions:From the results, it was concluded that agricultural lands around Pakistan Council of Scientific and Industrial Research (PCSIR) Campus Lahore were rich sources of industrially important Streptomyces, especially S. avermitilis.

Enhancement of clavulanic acid production by Streptomyces sp MU-NRC77 via mutation and medium optimization

“…It is noteworthy that a gradual reduction in survival rates was observed by the increase in UV exposure time on S. fradiae NRRL-2702. An enhancement in tylosin production by the resultant mutants compared to the wild type strains was detected [20].…”

“…The production of secondary metabolites by improved strains through mutagenesis techniques is considered an advantage during the fermentation process [20]. Random mutation by UV irradiation is a design for improving strains towards higher production [21].…”

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“…Carbon source utilization differed with a previous study. 20 The difference could have originated from differences in the study area in terms of the carbon sources present. According to 11 when actinomycetes grow in a certain environment, they get adapted to utilizing the carbon sources present.…”

“…18 Thermophilic actinomycetes are found in temperatures above 70 o C. 19 The ability to survive in these environments is pegged on their membrane structure which has membrane lipids that have more saturated and straight chain fatty acids than mesophiles. 20 This provides the right degree of fluidity needed for membrane function.…”

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology

“…Any change in the yield of antimicrobial production during OVAT or RSM optimization was determined by measuring zone of inhibition produced by culture filtrates. ISP2 media, which was found to be the most suitable antibiotic production media [ 19 , 20 ], contains malt extract, which consists of various malt hydrolyzed products as carbon source and yeast extract provides an organic nitrogen source and vitamin precursors to facilitate microbial growth. Aside from that it contains glucose as the principal carbon source for growth.…”