10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 3 2012 (July - September) Rare actinobacterial isolates belonging to the genera lessThan i greaterThan Micromonospora, Nonomuraea, Kribbella, Lechevalieria, Saccharotherix lessThan /i greaterThan and commonly occurring lessThan i greaterThan Streptomyces lessThan /i greaterThan were isolated from Limestone quarry - a unique and geographical area and harsh habitat. pH – 9.0, temperature – 45 lessThan sup greaterThan ° lessThan /sup greaterThan 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 lessThan i greaterThan Streptomyces lessThan /i greaterThan and DRQ 72 belonging to the genus lessThan i greaterThan Micromonospora lessThan /i greaterThan were very effective showing maximum zone of inhibition against the bacterial pathogen lessThan i greaterThan B. subtilis lessThan /i greaterThan (37 mm and 35 mm) and fungal pathogen lessThan i greaterThan Fusarium solani lessThan /i greaterThan (33 mm and 31 mm) respectively. The similar test isolates exhibited their higher efficacy with the MIC value of 2 µg/ml and 4 µg/ml for lessThan i greaterThan B. subtilis lessThan /i greaterThan and 4 µg/ml and 8 µg/ml for lessThan i greaterThan C. albicans lessThan /i greaterThan , and also showed more potency then the commercially available antibacterial drug, Ampicillin and antifungal drug, Nystatin. Syed Raziuddin Quadri And Dayanand Agsar Limestone Quarry, Soil sample, Rare actinobacteria, Antibacterial activity, Antifungal activity, Minimum Inhibitory Concentration 137-147