Antimicrobial Investigations from Crude and Peptide Extracts of Glycine max Linn. Merr Varieties

Four different genotypes of Glycine max, viz Rawal-I, NARC-II, SA-72-60 and Ajmeri, were subjected to antimicrobial investigation in the present study. Three types of extracts, i.e. aqueous, methanol and peptide, were prepared from the seed powder of each variety. Extracts were tested for their antimicrobial ability by agar well diffusion assay against 3 g-positive strains, i.e. Streptomyces laurentii, Enterococcus faecium and Microbacterium oxydans, and four gram-negative strains, i.e. Pseudomonas geniculata, Alcaligenes faecalis, Klebsiella pneumoniae and Bacillus subtilis. Rawal-I and NARC-II exhibited maximum antibacterial activity at higher concentrations with dose-dependent relationship against Streptomyces laurentii and Pseudomonas geniculata, whereas SA-72-60 and Ajmeri were found ineffective against all tested strains. Among three extracts prepared, aqueous and peptide extracts \({(12\pm0.14\,{\rm mm},\,11\pm0.07\,{\rm mm})}\) were more effective as compared to methanolic extracts. Different combinations of Rawal-I and NARC-II in 1:2 and 2:1 ratios were tested for antibacterial efficacies which exhibited no synergistic activity with few exceptions where antagonist interaction was shown by some of the extract mixtures. Preliminary phytochemical analysis of the effective extracts revealed the presence of antimicrobial constituents like flavonoids, alkaloids and saponins.