The
activity of the concentrated solvent extracts of four selected isolates
viz. SBSK-8 (Streptomyces sp.), SBSK-115 (Nocardiopsis sp.), SBSK-
120 (Kocuria sp.) and SBSK-356 (Micromonospora sp.) in six solvent
systems is shown in Table 2. These metabolites being extracellularly
produced can be easily extracted using organic solvents and the
compound(s) can be concentrated by evaporation in their active
forms. Different actinomycetes isolates showed a variation in the
activity profile with respect to the organic solvent used for
extraction of anti-bacterial compounds which suggests that these
potential metabolites produced, have inter-generic variations in
their chemical signatures. The concentrated residue of ethyl
acetate extract of isolate Streptomyces sp. (SBSK-8) showed
highest activity against three gram-negative bacteria viz. S.
typhimurium, E. coli and P. vulgaris with zones of inhibition
31 mm, 32 mm and 29 mm, respectively. Chloroform extract of
Micromonospora sp. (SBSK-356) against Vibrio cholera exhibited a
zone of inhibition of 35 mm (Fig. 7) suggesting the two
compounds to be peptides, fatty acids or amino acids. The
concentrated butanol extract of Nocardiopsis sp. (SBSK-115) gave
35 mm zone of inhibition against S. citreus, suggesting that the
active metabolite is either a fatty acid or a peptide whereas
butanol extracts of Streptomyces sp. (SBSK-8) showed with three
gram-negative bacteria. The concentrated residue of hexane