Antimicrobial attributes of rare actinobacteria detected from limestone quarries

Abstract

Rare actinobacterial isolates belonging to the genera Micromonospora, Nonomuraea, Kribbella, Lechevalieria, Saccharotherix and commonly occurring Streptomyces were isolated from Limestone quarry - a unique and geographical area and harsh habitat. pH - 9.0, temperature - 45°C and sodium chloride concentration - 3% were found to be optimum for the maximum growth and physiological ability of the test isolates indicating them as thermo-alkaliphilic in nature. It was found that, the test isolate DRQ 10 belonging to the genus Streptomyces and DRQ 72 belonging to the genus Micromonospora were very effective showing maximum zone of inhibition against the bacterial pathogen B. subtilis (37 mm and 35 mm) and fungal pathogen Fusarium solani (33 mm and 31 mm) respectively. The similar test isolates exhibited their higher efficacy with the MIC value of 2 4g/ml and 4 4g/ml for B. subtilis and 4 4g/ml and 8 4g/ml for C. albicans, and also showed more potency then the commercially available antibacterial drug, Ampicillin and antifungal drug, Nystatin.