ABSTRACT
A total of 9 actinomycetes (FA1-FA9) isolates were isolated from the soil and water samples using Starch Casein Agar and Actinomycetes Isolation Agar. All the isolates showed antimicrobial activity against at least one of the bacteria (Escherichia coli, Enterococcus faecalis, Klebisella pneumonia and Micrococcus luteus) tested except FA4 by cross streak method. The actinomycete isolate FA9 exhibited better antimicrobial efficacy for Gram negative (E. coli) than Gram positive organism (E. faecalis). Antimicrobial activity of the crude extract obtained from solid state fermentation showed a better zone of inhibitions from those obtained by submerged state fermentation. MIC of the crude extract was 0.51µg/ml for E. coli, 1.02µg/ml for E. faecalis, 0.51µg/ml for K. pneumonia and 1.02 µg/ml for M. luteus. The free radical scavenging ability (DPPH) of the ethanolic crude extract recorded IC50 value of 24.384. The FT-IR Spectral analyses of extracts showed functional groups like Alcohol (O-H), Alkanes (C-H), Alkene (C = C), Alkyl halide (C-F). The isolate FA9 was Gram positive and the spore chain morphology was simple rectus with a smooth spore surface. The 16S rRNA gene sequences were closely related to Nocardia alba. The RNA secondary structure predicted for 16SrRNA gene of Nocardia alba showed the free energy of -152.4 kkal/mol, threshold energy of -4.0 with Cluster factor 2, Conserved factor 2 and Compensated factor 4. The restriction sites prediction of the 16SrRNA gene of Nocardia alba showed restriction sites for Alu I, Hae III, BstUI etc. The restriction site analysis showed a GC content of 58% and AT content of 42%.
Key words: Key words
Antibacterial activity, MIC, DPPH, ft-ir, 16S rRNA, Nocardia alba.
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