The Isolation Of Fusarium Oxysporum Sp.Strain MJ-23, The Enzymatic Properties And Optimization Of Fermentation Conditions For Xylanase

Xylan is abundant in the nature and to be found in plant cell walls primarily. It formed to polysaccharide by β-1,4-glycosidic linkage. The plant feed contains a large amount of non-starch polysaccharides (NSP), which are not easy to be digested, so increasing the digestion viscosity of animals can reduce the feed amount and improve the absorption of nutrients. Different types of xylanase play a key role in improving the feed utilization, they work on the main and branched chain of xylan and degrade it to monosaccharides such as xylose.Now, people do much research on the strains of Aspergillus, Trichoderma, Penicillium, Mucor, but less on Fusarium sp..The main results obtained in this research are as follows:The strain Fusarium sp. MJ-23isolated from the soil can produce xylanase enzyme activity approximately186U/mL in the optimum conditions. By the morphological and rDNA-ITS gene sequence analysis, the Strain MJ-23was identified to Nectriaceae, Fusarium oxysporum sp..The optimized enzyme production conditions of the xylanase that produced by strain of MJ-23strain were as follows:the optimum reaction temperature was55℃and had enzyme activity in the range of50℃to60℃, the optimum pH was6, the selection solution dilution was200s, enzyme treatment time of20min, the amount of substrate was1mL.Different ions such as Ca2+, Fe2+, Mn2+had a strong activation to xylanase activity, but Cu2+, Zn2+had a greater inhibitory effect. Chemical additives of polyethylene glycol and Tween80had a larger role in promoting the activity of xylanase, but EDTA, urea especially SDS had the strongest inhibition effect.In the optimization of fermentation conditions, carbon sources such as xylan had the most significant induced effect to the xylanase. For nitrogen source, yeast extract, peptone, beef ointment all had a strong role in promoting the xylanase, but urea. The reason may be MJ-23had preference to different sources of nitrogen source.Too large or too small inoculation amount were all had impact to enzyme activity. We prefer5to10pieces of bacteria rent vaccination and50and75mL liquid volume in this study.When the xylanase used in pig feed, the generation amount of xylose can be increased by approximately28%and almost16%in the chicken feed. The differences may due to the corn content of the feed formula.