Abstract:
The increasing need of novel antibiotics has provided a pace for the search of antibiotics from actinomycetes. Primary and
secondary screenings of antibiotic producing actinomycetes from the soil of Siraha (75-600 m) were performed. The
minimum inhibitory concentration of the metabolites was determined against E. coli. Macroscopic, microscopic and
biochemical characterization were performed for the identi"cation of presumptive genera. Characterization of the
antibacterial substances was done by TLC.Among 92 isolates, 22showed antibacterial activity against at least 1 bacterium
out of 6 test bacteria used. Microscopy and other characteristics studies revealed that 19 (86.36%) were Streptomyces
spp.,1 (4.55%) was Thermomonospora spp., and 2 (9.09%) were unidenti"ed. Five potent isolates were selected for the
secondary screening where 2 isolates inhibited Gram negative bacteria with an MIC value of 1.2 mg/mL for each isolate.
TLC showed that both antibiotics produced only one spot suggesting the presence of one active compound other than
vancomycin (standard) . The active isolates from primary screening were heterogeneous in their overall macroscopic,
biochemical, and physiological characteristics. The two potent isolates showing antibacterial activity were found to belong
to different distinct taxonomic groups.
Description:
Central Campus of Technology, Hattisar, Dharan, Sunsari, Tribhuvan University, Nepal
2Central Department of Microbiology, Kirtipur, Kathmandu, Tribhuvan University, Nepal
