Study On The Biodegradation Of Phenolic Acids Accumulated On The Replanted Populous

The reasons for replanted problems are various, and the focus for present research is the accumulation of phenolic acids in the replanted rhizosphere soil. The excessive accumulation of phenolic acids will influence the roots and the micro-environment of the rhizosphere, which cause the decrease of the replant productivity and the survival rate of the plants. Some microorganisms with the ability of degradation of phenolic acids could be depended on the phenolic acids as the sole carbon source. So this research took Populous deltoids"I-69/55"as test material , took several common phenolic acids (ferulic acid, benzoic acid, p-hydroxybenzoic acid, cinnamic acid and vanillin) as the degradation targets, trying to select strains which could take the above phenolic acids as the sole carbon source, and their degradation efficiency, to explore the best culture conditions of the selected strains, and we release the selected strains to the second replanted soil environment according to their concentrations to evaluate their enviromental safty. The main results showed:1. 4 strains were selected from the second replanted poplar rhizosphere, which take ferulic acid, benzoic acid, p-hydroxybenzoic acid, cinnamic acid and vanillin as sole carbon source, that is F2, Aspergillus oryzae, B5 and B6. They are respectively identified asBasidiomycete yeast sp.,Aspergillus oryzae., Sinorhizobium sp. and Pseudomonas putida.2. The degradation ability of 4 strains to ferulic acid, benzoic acid, p-hydroxybenzoic acid, cinnamic acid and vanillin is well. The degradation rate of 4 strains to ferulic acid reached 90% after 96h's treatment. The degradation ability to ferulic acid: B6>Aspergillus oryzae>B5>Basidiomycete yeast sp.. The degradation rate of 4 strains to benzoic acid is good, and the degradation ability of fungi of is higher than that of bacteria. The degradation ability to benzoic acid:Basidiomycete yeast sp. > Aspergillus oryzae>B5>B6. The degradation rate to p-hydroxybenzoic acid of Aspergillus oryzae, B5 and B6 reached 80% after 24h, reached 90% after 48h. The degradation to p-hydroxybenzoic of 4 strains: B5>B6>Aspergillus oryzae>Basidiomycete yeast sp.. The degradation ability of Aspergillus oryzae to cinnamic acid is better as its degradation rate reached 93.9% after 24h; the degradation rate of Basidiomycete yeast sp. and B5 to vanillin reached 99% and 98.2% respectively. The degradation ability of 4 strains to cinnamic acid: Aspergillus oryzae>Basidiomycete yeast sp. >B5>B6. The degradation ability of fungi to vanillin is better than that of bacteria. The degradation ability of 4 strains to vanillin:Basidiomycete yeast sp. >Aspergillus oryzae>B6>B5. All the degradation course could be simulated by unary quadratic equation very well, with R2>0.8.3. The best culture condition for Basidiomycete yeast sp. is pH=7,T=35℃in conditions of mixed phenolic acids. The amount of Basidiomycete yeast sp. under weak acidity (pH=6; pH=7) is larger than that of weak-alkaline. The best culture condition for Aspergillus oryzae is pH=7,T=40℃. Acidity and low temperature is not good for the proliferation of Aspergillus oryzae. The best culture condition for B5 is pH=8, T=35℃. Alkaline and high temperature is good for the proliferation of B5. The best culture condition for B6 is pH=8, T=35℃. The higher the temperature, the larger the amount of B6.4. The number of bacteria and actinomycetes first decreased and then decreased, while the fungi did the opposite with Basidiomycete yeast sp. /Aspergillus oryzae of different concentrations. The number of bacteria and actinomycetes decreased significantly after 30d's treatment, the number of fungi increased significantly after 30d's treatment, multiple comparisons reached a very significant level(p=0.01). The amount of all microbial community were back to the original number after 60d's treatment, which showed that the release of Basidiomycete yeast sp./Aspergillus oryzae to soil were safe.The number of actinomycetes first decreased and then increased, while the bacteria did the opposite with B5/B6 of different concentrations, the amount of fungi didn't show significant changes. The number of actinomycetes and fungi decreased significantly after 30d's treatment, the number of bacteria increased significantly after 30d's treatment, multiple comparisons reached a very significant level(p=0.01). And the higher the concentrations, the higher the amount of bacteria. At the time of 60days, with the treatment of B5 of low concentrations (concentrations of 1 and 5) and B6 of all concentrations, The amount of all microbial community were back to the original number after 60d's treatment, which showed that the release of B5(concentrations 1 and 5)/B6 to soil were safe.The amount of microorganism community didn't show significant change at any time at the treatment of 4 mixed strains of all concentrations, so the release of the mixed strains to environment were safe.The selection, identification, evaluation of degradation rates and culture conditions of strains which have strong degradation ability of 5 phenolics will be carried out in this study, and soil security of selected strains will be carried out in rhizospheric soil of poplar. The studies above are innovations and breakthrough in the field of regression of planted forest of poplar. Desired performance will promote forest scientific research level in our province greatly, and the application of research results to practice, ecological, great social and economic effects will be produced.