Optimization of culture conditions of Streptomyces rochei (MTCC 10109) for the production of antimicrobial metabolites

Abstract

Fermentation and culture conditions were studied in shaken-flask culture to induce the production of greater amounts of antimicrobial metabolites by Streptomyces rochei (10109). Antimicrobial metabolite production started after 48 h incubation and reached its optimum level at 20% inoculum size at 120 h, at which point the metabolites showed maximum antifungal and antibacterial activity against selected human pathogenic microorganisms (Candida albicans, Staphylococcus aureus and Escherichia coli). Optimal production occurred at pH 7.5 and temperature 32°C, with 2% glycerol and 1% peptone as the carbon and nitrogen sources respectively. The effects of adding sea water (optimum 30%) and NaCl (optimum 1%) were also evaluated.

Optimization of Culture Conditions for Production of Bioactive Metabolites by <i>Streptomyces</i> spp. Isolated from Soil

“…The cell free supernatant thus obtained was concentrated five-fold in the vacuum concentrator and 50 µl was used to determine antimicrobial activity. The diameters of zones of inhibition were noted [11].…”

“…Actinomycete cell metabolism under conditions of nutritional excess is known to be directed towards the generation of cell mass rather than production of secondary metabolites. Also, glucose is known to cause catabolite repression, in which production of enzymes of secondary metabolite bio-synthesis is inhibited [11] [20]. It has been observed that secondary metabolite production is often stimulated by slowly assimilated complex carbon sources like polysaccharides [21].…”

“…Peptone followed by casein has been observed to be the best nitrogen sources by Gopi Reddy et al, on their studies on S. rochei [11]. Peptone has been found to favour antibiotic production by other authors too [28] [29].…”

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“…Secondary metabolite production is often stimulated by slowly assimilated complex carbon sources like polysaccharides. A possible explanation for this phenomenon is that glucose causes catabolite repression, in which production of enzymes of secondary metabolite biosynthesis is inhibited 7,[23][24] . Starch has been found to be the best carbon source for antibiotic production by Gao et al 25 .…”

“…Changes in the nature and type of carbon and nitrogen sources have been reported to affect antibiotic biosynthesis in Streptomyces [6][7] . Also several cultivation parameters like pH, incubation period and temperature play a major role in the production of bioactive metabolites 8 .…”