SCREENING OF POTENTIAL ANTIBIOTIC PRODUCING ACTINOMYCETES EXTRACTED FROM SOIL AND WATER SAMPLES FROM DIFFERENT REGIONS OF KATHMANDU VALLEY

Abstract

Actinomycetes are Gram-positive, aerobic spore forming bacteria that are characterized by aerial and mycelial growth and are chief antibiotic producers. The aim of this study was to screen antibiotic producing actinomycetes and determine its antibiotic activity against ATCC cultures. A total of 60 samples (30 water and 30 soil) were collected from different regions of Kathmandu Valley viz. Kathmandu, Lalitpur and Bhaktapur spanning from the month of March 2022 to May 2022. Spread plate technique was employed to isolate the actinomycetes on Starch M-Protein Agar, and primary and secondary screening techniques were performed via Perpendicular Streak method and Agar-well diffusion respectively for screening their ability to produce antibiotics. The actinomycetes were confirmed by the macro and microscopic examination, biochemical and physiological tests. The crude extract obtained from the submerged state fermentation was filtered and centrifuged; tested against the Standard cultures viz; Staphylococcus aureus ATCC 43300, Escherichia coli ATCC 35218, Escherichia coli ATCC 25922 and Klebsiella spp. ATCC 700603 via agar well diffusion method. Out of the 28 (93.3%) isolates obtained from 30 soil samples, only two isolates (7.3%) i.e., NP1 and MI4 showed antimicrobial activity against the ATCC cultures which were presumed to be Streptomyces. No actinomycetes were obtained from water samples. ANOVA revealed no significant difference at 5% level of significance (0.535; P>0.05) between the standard streptomycin (100 µg/ml) and NP1.The soil of Kathmandu Valley harbors microbial diversity that encompasses potential antimicrobial producing actinomycetes which in turn can help in booming the economy by enabling the production of indigenous antibiotics.