Screening And Functional Characteristics Of Vanillic Acid Degrading Bacteria In Peanut Rhizosphere

The phenolic acid vanillic acid was used in this study.Bioassay and molecular identification were carried out by means of enrichment and plate coating on peanut rhizosphere soil.The degradation ability of vanillic acid and the broad-spectrum of phenolic acid degradation were studied.Finally,the germination test of peanut seeds with different treatments,such as degradation bacteria,vanillic acid and vanillic acid,was carried out,and the inhibition of vanillic acid on peanut growth and the validity of vanillic acid degradation by degrading bacteria were verified by greenhouse substrate germination test.The main findings are as follows:(1)Twenty-four strains of vanillic acid-degrading bacteria were screened from the roots of peanut.After preliminary identification by microscopic observation of bacteria growth and identification of molecular level,the growth condition was the best.The most biodegradable strain was named WL-5.(2)under the condition of vanillic acid as the sole carbon source,the degradation solution of bacteria was obtained in the inorganic salt medium containing vanillic acid concentration of 2mmol·L~-11 at 30?and 160 r·min~-11 for 36 h.The maximum and lowest residual amount of vanillic acid and bacteria growth were determined by ultraviolet spectrophotometry.(3)The degradation ability of vanillic acid by WL-5 was studied under different pH,temperature,substrate concentration and substrate specificity.The results showed that the suitable conditions for degradation of bacteria WL-5 were pH=6-7,temperature 35?,substrate concentration 4mmol·L~-11 and biodegradable bacteria with certain ability to degrade other autotoxic substances.(4)seed germination test showed that the degradation bacteria WL-5 had little inhibition on peanut seed germination,but vanillic acid significantly inhibited peanut seed germination.The degradation of vanillic acid by bacteria increased with the increase of the concentration of vanillic acid.(5)The results of soil culture in greenhouse showed that vanillic acid could inhibit the emergence of peanut,and the inhibition effect of vanillic acid on peanut seedling was improved after adding degrading bacteria,which was reflected in plant height,stem diameter,leaf area and dry weight of shoot.There were significant differences in fresh weight,and no obvious inhibition of peanut emergence was observed by biodegradable bacteria.