BIO-CONTROL OF BACTERIAL PATHOGENS WITH SOLVENT EXTRACTS OF WEEDS OF AMARANTHACEAE FAMILY

Abstract

Biologically active substances have been isolated from weedy plants and investigated against bacterial pathogens for their antimicrobial potential. Medicinal value and biological functions of weeds are being tapped in order to find out novel substances against microorganisms which have developed resistance to current antibiotics and pesticides. Major objective of the current study was to investigate the antiphytopathogenic potential of the organic extracts of root, stem and leaves of weeds from the family Amaranthaceae (Amaranthus viridis L. and chenopodium murale) against seven bacterial species viz, Bordetella pertussis, Kurthia gibsonii, Burkholderia pseudomallei, Azotobacter nigricans, Phenylobacterium immobile, Azomonas agilis, Enterobacter intermedius.  We observed significant results with the application of   organic leaf and stem extracts on tested pathogens using well diffusion method whereas aqueous extracts exhibited lower efficacy.  Methanolic stem extract (MSE) of A. viridis showed maximum inhibition against Azotobacter nigricans (40±0.08), Enterobacter intermedius (39±0.24), Phenylobacterium immobile (37±0.04), Azomonas agilis (34±0.19) respectively. Methanolic root extract (MLE) of A. viridis were more effective to inhibit the growth of Bordetella pertussis (42±0.24), Kurthia gibsonii (37±0.09). whereas methanolic leaf extracts were significantly effective against Burkholderia pseudomallei (40±0.13). Significant growth inhibition was also observed in bacterial strains when treated with methanolic stem extract (MSE) of C. murale.  against Azotobacter nigricans (38±0.15), Bordetella pertussis (36±0.24) and Phenylobacterium immobile (34±0.04) respectively. Methanolic leaf extracts of C. murale showed maximum inhibition against Kurthia gibsonii (40±0.19), Burkholderia pseudomallei (36±0.19) and Enterobacter intermedius (38±0.08) and root extracts was effective against Azomonas agilis (30±0.19). Both of the species exhibited diverse biochemical compounds in aqueous and organic extracts. Results obtained clearly indicates that antimicrobial constituents of Amaranthus viridis L. and Chenopodium murale weeds can be screened for the isolation of alternative antibacterial compounds to develop novel biopesticides against resistant bacteria.