Screening And Functional Characterization Of Cinnamic Acid-Degrading Strains From Cucumber Rhizosphere Soil

In this study, two strains which can degrade cinnamic acid efficiently was isolated and screened from cucumber rhizosphere soil with cinnamic acid as the sole carbon source. The strains was proceed biological identification, degradation ability, degradation characteristics and biometrics, the degradation effect of two CA-degrading strains was verified through the cucumber seed germination experiment and greenhouse soil culture experiment.The main results were as follows:(1) The CA-degrading strains named fungi2-4and bacteria42-3were identified as Aspergillus niger and Pseudomonas putida by morphological, physiological, biochemical and molecular analysis. They were conserved in the agricultural microorganism resources conserved center of Shandong, and their conservasion numbers is AMCC300047and AMCC100141.(2) After cultured in liquid mineral salt medium containing2.0mmol·L-1of cinnamic acid at30℃, pH7.0,160r-min-1for12h and72h, the degrading rates of fungi2-4and bacteria42-3were reached99.35%and99.62%.(3) The single factor tests degradation characteristics for the CA-degrading strains showed the appropriate conditions for the degradation fungi2-4was temperature30℃-35℃, pH4.5-5.5, the appropriate conditions for the degradation bacteria42-3was temperature25℃-30℃, pH6.0-8.0, in addition, two CA-degrading strains also have a broad spectrum degradation characteristics of phenolic acids.(4) The biological function measurement results of CA-degrading strains showed that:the degradation fungi2-4have different of antagonism effect with Fusarium oxysporum f.sp. Cucumerinum、Fusarium prolifertum、Fusarium moniliform etc; The fermentation liquid of the degradation bacteria42-3has growth-promoting effect on the cucumber seed germination and cucumber seedlings growths.(5) Cucumber seed germination test with different time degradation liquid of degradation fungus2-4was as follows:0h degradation liquid significantly inhibited cucumber seed germination, with the increase of degradation time, the inhibition effect of degradation liquid on the cucumber seeds gradually reduced,72h degradation liquid treatment showed similar effects with CK treatment on the cucumber germination. (6) Greenhouse experiment showed that the growth of the cucumber seedlings treated with cinnamic acid was significantly inhibited, and the inhibition of cinnamic acid stress could be alleviated obviously after joining CA-degrading strains, and bacteria42-3showed the best effect.