RÉSUMÉ
The heavy metal resistant bacterium isolated from field soil and identified as Enterobacter sp. RZS5 tolerates a high concentration (100-2000 mM) of various heavy metal ions such as Mn2+, Ni2+, Zn2+, Cu2+, CO2+ and Fe2+ when grown in such environment and produces exopolysaccharides (EPS). Here, we have demonstrated EPS production by Enterobacter sp. RZS5 during 60 h of growth in yeast extract mannitol broth (YEMB). The yield increased by two fold after the addition of 60 M of Ca2+; 50 M of Fe2+ and 60 M of Mg2+ ions in YEMB, and the optimization of physico-chemical parameters. EPS was extracted with 30% (v/v) of isopropanol as against the commonly used 50% (v/v) isopropanol method. EPS-rich broth promoted seed germination, shoot height, root length, number of leaves and chlorophyll content of wheat (Triticum aestivum) and peanut (Arachis hypogaea) seeds. The higher colony-forming unit of Enterobacter sp. in soil inoculated with EPS rich broth of Enterobacter sp. indicated the root colonizing potential and rhizosphere competence of the isolate. The FTIR spectra of the EPS extract confirmed the presence of the functional group characteristics of EPS known to exhibit a high binding affinity towards certain metal ions. This overall growth and vigour in plants along with the effective root colonization, reflected the potential of the isolate as an efficient bio-inoculant in bioremediation.
Sujet(s)
Arachis/effets des médicaments et des substances chimiques , Arachis/croissance et développement , Arachis/métabolisme , Dépollution biologique de l'environnement/effets des médicaments et des substances chimiques , Chlorophylle/métabolisme , Enterobacter/effets des médicaments et des substances chimiques , Enterobacter/métabolisme , Enterobacter/physiologie , Germination/effets des médicaments et des substances chimiques , Interactions hôte-pathogène , Métaux lourds/métabolisme , Métaux lourds/pharmacologie , Feuilles de plante/effets des médicaments et des substances chimiques , Feuilles de plante/croissance et développement , Feuilles de plante/métabolisme , Racines de plante/croissance et développement , Racines de plante/microbiologie , Pousses de plante/effets des médicaments et des substances chimiques , Pousses de plante/croissance et développement , Pousses de plante/métabolisme , Polyosides bactériens/biosynthèse , Polyosides bactériens/pharmacologie , Graines/effets des médicaments et des substances chimiques , Graines/croissance et développement , Graines/métabolisme , Sol/composition chimique , Microbiologie du sol , Spectroscopie infrarouge à transformée de Fourier , Triticum/effets des médicaments et des substances chimiques , Triticum/croissance et développementRÉSUMÉ
Pseudomonas aeruginosa isolated from banana field rhizosphere produced different antifungal metabolites like bactriocin, hydrogen cyanide and siderophore. Bacteriocinogenic, siderophoregenic, and HCN rich broth of isolate inhibited the growth of phytopathogen like Aspergilus niger, Aspergilus flavus, Fusarium oxysporum and Alternaria alternata. The isolate exhibited more antifungal activity and comparatively low MIC vis-a-vis commonly used copper based systemic chemical fungicide;bil cop.