Screening And Application Of Cellulose Degrading Fungi With Plant Growth Promoting And Disease Resistance Ability

This experiment aimed to screen fungi strains with cellulose degrading, phosphorus dissolving, IAA producing and pathogen resistant ability, and be used for multi-functional straw rotten agent. The soil samples were collected from Wenjiang and Chongzhou, and fungal strains were isolated with dilution methods, then, nine cellulose-degrading fungi with plant growth promoting and antagonism function was screened by qualitative test, and further evaluated by quantitative analysis. Based on the thallus morphology observation, colony morphology, ITS sequence analysis, their taxonomic position was determined; and then nine effective strains were selected, their straw degrading ability were determined, and the influence of seed germination rate by elution liquid from rotten wheat straw was detected. Combined all the results, the three most effective fungal strains were chosen for pot-experiment to verify their soil quality improving capacity. The results were as the follows.A total of 183 fungal strains were isolated from the soil samples collected from Wenjiang and Chongzhou. Using qualitative test, nine cellulose degrading fungal strains with multiple functions were screened and named WJF17, WJF29, WJF40, WJF43, WJFS17, CZF55, CZF60, CZF63 and CZF130. According to the quantitative experiment, the CMCase activity of the tested fungal strains in liquid medium and solid medium was 6.19?89.97 U·min-1·mL-1 and 188.09?605.32 U·min-1·g-1; and FPase activity in liquid medium and solid medium showed 2.25?10.86 U·min-1·mL-1 and 32.43?127.81 U·min-1·g-1, respectively. The phosphorus dissolving ability was between 194.37?1538.19 mg·l·3d-1 in the medium with 5.0g·L-1 of Calcium phosphate, and their indole acetic acid yield was between 3.87?12.50 g·mL-1·3d-1 in the medium with 0.5g·L-1 of L-tryptophan. All the 9 fungi showed good antagonism ability to the test pathogenic fungi and target bacterial strains.Using morphological observation method, and ITS fragment sequence analysis technique, the 9 fungal strains were identified. The results showed that these fungal strains belonged to 5 genera, and distributed into 8 species. Strain WJF17, WJF29 belonged to Aspergillus flavus; WJF40, WJF43, CZF55, CZF60, WJFS17, CZF63, and CZF130 belonged to Aspergillus fumigatus, Aspergillus niger, Penicillium chrysogenum, Penicillium cyclopium, Talaromyces purpurogenus, Trichoderma harzianum, Rhizopus oryzae in the taxonomy, respectively.By the wheat straw degrading experiment, the tensile strength, the change of cellulose and hemicellulose content of the wheat straw was determined. The results suggested that, after 30d's treatment, the tensile strength of wheat straw was decreased 1.90%?47.70% than that of control; the straw cellulose content reduced from about 40% to 6.83%?15.96%; however, the hemicellulose content hadn't significantly changed. The vegetable seed germination rate by adding leaching solution of rotten wheat straw was determined and the results suggested that the leaching solution of rotten wheat straw could improve the seed germination rate of the most vegetable tested, and the highest achieve value reached to 11.67%.According to the experimental results above, three fungal strains, Aspergillus niger WJF43, Penicillium chrysogenum CZF55 and Talaromyces purpurogenus WJFS17, were screened as high efficiency plant growth promotion fungal strains, and used to do the proof test for their promotion ability by pot experiment. Five treatments were designed, T1:the control, no straw and fungal inoculants added; T2:wheat straw + solid fungal inoculants; T3:wheat straw added alone; T4:rotten straw+solid inoculants; T5: rotten straw added alone. The results were evaluated after 30 days, the results revealed that T4 was the best one, and the content of organic matter, soil microbial carbon, soil microbial nitrogen was increased 22.20%,46.10%,42.41% compared with the control, respectively; and the phosphorus content of Brassica narinosa Bailey was increased by 15.56%, and the yield was increased by 47.25%. The results suggested that WJF43, CZF55 and WJFS17 were effective fungi with high cellulose degradation, plant growth promotion, the antagonism function of fungi ability, and had a good application prospect.