Screening of antimicrobial activity and polyketide synthase gene identification from the Actinomycetes isolates

Abstract

The Streptomyces genus is well studied owing to its capacity in producing more than 70% of antibiotics. This study was undertaken to characterize Streptomyces strains, occurring in soils of different districts of Tamilnadu, India as well as to evaluate their potential to produce antimicrobial compounds. Samples were collected from rice rhizosphere from different district of Tamilnadu agricultural zone. In primary screening by cross streak method, Streptomyces strains were assessed for antibiotic production and activity against different human bacterial. Then active isolates were selected for secondary screening by agar well diffusion method. Solvent extraction method was used to identify the best crude samples which are exhibiting better antibacterial activity. Then, 16S rRNA PCR was carried out for confirmation of isolates. In primary screening among all of the isolates, 50% isolates were active against at least one of the test organisms and 21.31% strains exhibited a broad-spectrum activity against almost all of the test bacteria. The minimum inhibitory concentrations (MICs) of the ethyl acetate extracts measured. Out of 26 positive strains two of the most active isolates SVG-07-15 and TK-01-05 were taken for further studies. These results highlight the importance of Streptomyces isolates in antibiotic production. Together with antibacterial activity, the PKS gene based approach can be applied for efficient screening of isolated strains of pharmaceutical value and related compounds. HighlightsO_LIIsolation of actinomycetes from soil samples collected from South India. C_LIO_LIScreening of isolated actinomycetes for antibacterial activity C_LIO_LIDetails study of potent strains against human pathogens C_LIO_LIIdentification of PKS gene from the active strains C_LI