Enhancement of Enterobacter Cloacae Antagonistic Effects Against the Plant Pathogen Fusarium Oxysporium

Abstract

Abstract: The present investigation aimed to enhance and producing high efficient antagonistic mycoparasites to control the soilborne plant pathogens F. oxysporum f. sp. sesame and F. oxysporum f. sp. vicia which cause root wilt disease. Among several bacterial strains tested for their efficiency in inhibiting F. oxy. f. sp. sesame and F. oxy. f. sp. vicia growth, P. aeruginosa and E. cloacae had the highest antagonistic effects. E. cloacae antagonistic genes expression studies were carried out by using different carbon sources. No antagonistic effect against F. oxy. f. sp. sesame has been found in E. cloacae culture filtrate when grown with glucose as a sole carbon source. Using 1% chitin as a sole carbon source could enhance the antagonistic effects of E. cloacae. The highest inhibition effect was found when E. cloacae was grown for two days on glucose as a sole carbon source, then for five days on chitin -medium. E. cloacae filtrate was more efficient in inhibiting F. oxy. f. sp. sesame growth than in F. oxy. f. sp. vicia which may reflect differences between the two pathogen forma specials. Hybrids of E. cloacae and P. aeruginosa were produced by fusion of the bacterial protoplasts. About 25% of P. aeruginosa and 42% of E. cloacae cells were converted to protoplasts. The best protoplast fusion percentage was found in ten minutes after protoplasts mixing in the presence of 25% PEG 6000. The obtained fusants were very unstable which may due to the difference between both genera