Screening Of Ferulic Acid Degrading Actinomycetes And Their Degradation Effect

Ferilic acid is one of the most important autotoxicity of watermelon,which cause continuous cropping obstacle.This study aimed at overcomeing the continuous cropping obstacles of watermelon through the degradation of watermelon autotoxins by actinomyces.24 strains of actinomyces which can degrad ferilic acid were isolated and screened from 127 strains of actinomyces from extreme environments of northwest Chinese and the north slope of the main peak of Qinling.The study of their antagonistic effects on Fusarium oxysporum of watermelon and melon was taken.There of them were used to investigate the ability in degrading watermelon autotoxins in liquid culture under different condations.The experiment that their effects on the growth of watermelon and root morphology were also carried on. The main results are as follows:1. These actinomyces both have inhibiting effect on the four pathogenic fungi of watermelon and melon.24 strains of actinomyces have different inhibiting effect on the four pathogenic fungi: F.oxysporum1 F.oxysporum2, Fusarium equiseti and Fusarium oxysporum schlechlendahl f.sp.. Eleven actinomycets strains have strong inhibition to Fusarium equiseti, Antagonistic diameters is 14mm to 20mm. Act80,ActS11,ActX7,ActZ4,ActZ20 and ActZ30 have strong antagonistic effect on four pathogenic fungi, and antagonistic diameters is 13mm to 20mm.2. Three strains of actinomyces have high degradation rate of ferulic acid in Liquid fermentation. Three strains of actinomyces: Act25,Act28 and ActZ30 have been screened which have high degradation rate of ferulic acid under different concentrations of ferulic acid and starch. Ferulic acid degradation rate of Act25,Act28 and ActZ30 is 94.32%,92.61% and 90.05% respectively in system which ferulic acid was used as single carbon source.,Three strains of actinomycetes showed different degradation ability on ferulic acid in mixed carbon culture conditions.The degradation rate of ferulic acid of 3 strains of actinomyces are from 95.2% to 100% in four kinds of starch concentration when the concentration of ferulic acid is 50mg/L. The degradation rate of ferulic acid of 3 strains of actinomyces are from 68.6% to 96.6% in four kinds of starch concentration when the concentration of ferulic acid is 100mg/L.The degradation rate of ferulic acid in three actinomycetes as pure cell is low It was 7.63%,2.80%,5.60% when the concentration of ferulic acid is 50mg / L and 0.62%,0.74%,5.93% when the concentration of ferulic acid is 100mg / L3. High concentration of degradation solution of actinomycetes can effectively alleviate the toxicity of ferulic acid to watermelon. The radieles of watermelon were short,more side root,and root tip tissue be came brownish which were irrigated by ferulic acid solution(100mg/L). The degradation solution of ferulic acid(100mg/L)inoculate with Act25 can effectively promote the growth of watermelon seedlings and effectively eliminating the autotoxicity of ferulic acid.The plant height, plant weight, root length and root weight of watermelon seedlings irrigated by high concentration of degradation solution of Act25 were significantly higher than that by high concentrations of ferulic acid.