Optimization of culture conditions for antimetabolite production by a rare tea garden actinobacterial isolate, Amycolatopsis sp. ST-28

Abstract

Background: Microbial metabolites are of great importance to the pharmaceutical industries. There is an urgent need of novel microbial metabolites in the present scenario to combat antimicrobial resistance. Selection and screening of potent microbial strains for production of antimicrobial metabolites as well as optimization of their culture conditions is of utmost importance in drug discovery. Therefore, the study was carried out to evaluate the effect of nutritional and cultural conditions on the production of bioactive metabolites by a rare tea garden actinobacterial strain Amycolatopsis sp. ST-28.

Materials and methods: Submerged fermentation of the actinobacterial isolate was carried out on different culture media and different culture conditions such as carbon and nitrogen sources, inoculum volume, pH, fermentation period and agitation speed. The culture filtrate was assayed against Staphylococcus aureus. Agar well diffusion method was employed to determine the maximum diameter of zone of inhibition (mm). The dried mycelial weight (mg) in a fixed volume of culture media was used for the determination of the total biomass produced.

Results: Maximum bioactive metabolite and biomass production was observed when submerged fermentation was carried out with mannose and peptone respectively as a sole carbon and nitrogen source. Maintaining other environmental parameters viz. inoculum 11% (v/v), pH of 6.5, temperature of 32ºC and incubation period of 11 days at 150 rpm were found optimum for maximum antimicrobial activity.

Conclusion: This study demonstrated optimized cultural conditions for improved production of antimicrobial compound by Amycolatopsis sp. ST-28

Keywords: Amycolatopsis, antimicrobial, submerged fermentation, optimization