Original Articles: 2011 Vol: 3 Issue: 3
Bioprospecting of actinobacteria from Yelagiri hills with special reference to antibacterial activity
Actinobacteria are the group of ecologically and industrially important prokaryotes but their distribution and utilization from hills/forest ecosystems especially are very less interms of bioactive molecules. With this view an attempt was made for the exploitation of actinobacteria from Yelagiri Hills with special reference to antibacterial activity. Actinobacteria from Yelagiri hill soil was isolated using starch casein agar and the counts were ranged between 1.5X104 and 6X104cfu/gm of soil. Based on the cultural morphology about 40 actinobacterial isolates were selected for further investigations. In antibacterial screening against Staphylococcus aureus, Streptococcus species, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa by agar plug method, about 50% of the actinobacterial isolates was inhibited atleast any one of the six bacterial pathogens tested. In particular, strain number YA3 (7-17mm zone of inhibition) and YF2 (9-16mm zone of inhibition) showed broad spectrum activity. Bioactive metabolites from YA3 and YF2 were produced by adopting submerged fermentation using ISP2 broth. In agar well diffusion method culture filtrate from strain YA3 showed promising activity when compared to YF2. Further crude extract from the YA3 culture filtrate was extracted using ethyl acetate and n-hexane and tested for antibacterial activity by disc diffusion method. Only the ethyl acetate extract showed good activity against all the test bacterial pathogens. In thin layer chromatographic separation, the crude ethyl acetate extract of strain YA3 produced two spots with Rf value of 0.76 and 0.83. In bioassay guided fractionation, both the spots showed antibacterial activity. Based on the studied phenotypic characteristics strain YA3 was suspected as Streptomyces species. Findings of the present study conclude that Yelagiri hill is the potential ecosystem for antagonistic actinobacteria which deserves for bioprospecting. The antagonistic actinobacterium YA3 will be a good candidate for the isolation of antibiotic molecule since it showed good activity in the preliminary and secondary screening experiments and it also from an underrepresented ecosystem.