Screening Of Lignin Degrading Fungi And The Optimization Of The Condition Of Fermentation By Oil Palm Fiber

Disposed as a kind of garbage,palm fiber not only pollutes the environment but also causes the waste of resources.One of the key factors which affects the efficient utilization of palm fiber is the blocking effect of lignin.In this thesis,the research on the screening of palm fiber degradation fungi,the optimization of fermentation conditions and the lignin degradation were carried out to provide strain resources and technical support for the comprehensive utilization of palm fiber.The main results were as follows:(1)Through separation experiment by WA culture medium,8 strains(respectively indicated as Q1,Q2,Q3,Q4,Q5,Q6,Q7 and Q8)which met the experimental requirements were separated successfully.The strain pc530 which was conserved in our lab was taken as a reference to judge the order of enzyme activity of the strains by guaiacol screening culture medium and the order was:Q1>Q2>Q6>Q5>Q7>pc530.Through further screening experiment by Aniline blue plate medium and the lignin degradation screening experiment as well,the strain Q1 which could degrade the lignin of the palm fiber effectively was screened and cultured successfully in the end.(2)The strain pc530 was taken as the contrasting strain to research the growth and enzyme production characteristics of the strain Q1 to explore the relationship between growth and enzyme production.Besides,the culture conditions of enzyme production by the strain Q1 were optimized through the single factor analysis and the orthogonal experimental method.The result showed that after 8 days of static culture,MnP activity could reach 1926U/L and the total activity of MnP and LiP could reach higher than 2300 U/L under the following condition:Glucose,10g/L;Ammonium tartrate,0.33g/L;Benzyl alcohol(added after 2 days of culture),5.2mmol/L;culture temperature,30℃;pH,4.5.The total enzyme activity of the strain pc530 was about 1100 U/L under its best enzyme production condition which showed that the enzyme production performance of Q1 was obviously superior to that of pc530.(3)The strain pc530 was taken as the contrasting strain to research the degradation of the lignin of the palm fiber by the strain Q1 under the optimized conditions.The palm fiber was added in the reaction system at different time and the degradation rates were compared.The result was as follows:in 3 days,the degradation rate of the lignin reached 26%,but it tended to be slow at the later stage,especially on 11th-15th day with the rate of only 2%;After 15 days,the degradation rate reached higher than 37%.The maximum degradation rate of the lignin by pc530 was only about 10%.The result showed the superiority of the strain Q1 and the significance of the optimization of the enzyme production conditions.