Characterization of antibiotic meta bolites from actinomycete isolates

Abstract

: Metabolites from three actinomycetes isolates coded CS35, 28P and 14P antagonistic to Pythium spp were produced in shaken liquid media and centrifugation done to obtain cell free culture filtrates. The antibiotic metabolites from each of these isolates was characterized by performing chromatography & bioautography, partial purification, determination of minimum inhibitory concentration (MIC) and determining the effect of temperature, pH and shelve life on the stability of these metabolites. Rf values from the chromatography work and bioautography showed that, metabolites from CS35 and 14P had only one active compound whereas metabolite from isolate 28P had 2 active compounds. The antibiotic metabolites from isolate 28P and CS35 were stable up to a temperature of 70 0 C but were sparingly stable at 80 0 C. The stability of antibiotic metabolite from isolate 14P was drastically reduced from a temperature of 60 0 C and above. High pH value (above 10) and low pH values (below 4.0) negatively affected the stability of the metabolites. Metabolites from isolate 14P lost stability with time whereas metabolites from isolates CS35 and 28P maintained their activity for the entire duration (5 months) tested. These metabolites were found to be sufficiently stable under different conditions and they possess a high potential to control the disease problems under field conditions.