Studies On Biodegradation For Rape Straw By White-rot Fungi And Fermentation Of Residue To Feedstuff

The strain Pleurotus ostreatus WY01 was chose as studying material in this experiment.Firstly,the strain was mutagenesised by the ultraviolet irradiation,and a high producing strain ADW-08 was screened.Then,the culture medium and the fermentation conditions of the mutagenic strain ADW-08 were studied.Finally,the composition of ligninolytic enzyme excreted by ADW-08,the rape straw biodegradation by ADW-08 and application for its fermentation residue for cows were studied.The ultraviolet irradiation indicated:As the irradiated time was 50 seconds,the lethality rate of spores was between 70%and 80%and the mutation rate was at the highest level,so 50s was definited as the optimum irradiated time.The peak activity of Laccase of mutated strain ADW-08 was raised from 2.78U/g excreted by Pleurotus ostreatus WY01 to 7.78U/g.Characteristics of enzymes production in ADW-08 kept stable by 5 times subculture.By single and orthogonal test,a culture medium for the Laccase production by ADW-08 was studied.The optimal solid medium consists of 15g/L glucose,0.4g/L ammonium tartrate,0.25g/L MnSO₄·H₂O.The study on optimal fermentation conditions of the mutagenic strain ADW-08 was indicated:the optimum fermentation temperature was 28℃,pH was 5.0 and seed volume was 3 germ bungs/20g.Laccase was induced effectively by ABTS(1mmol/L) and veratryl alcohol(1mmol/L),and inhibited by Tween-80(1%).The optimal solid medium for lignin biodegradation consists of 15g/L glucose,0.4g/L ammonium tartrate,0.75g/L MnSO₄·H₂O.The study on the ligninolytic enzyme composition of ADW-08 and the rape straw biodegradation indicated:the ligninolytic enzyme composition of ADW-08 were Laccase and MnP.The peak values of Lacease and MnP were 6.67 U/g and 2.67U/g at 24th day respectively.By 60 days fermentation,the degradation rates of lignin,cellulose and hemicellulose were 56.28%,40.80%and 45.22%respectively,and the content of crude protein,essential amino acid and total amino acid were raised by 43.73%,135.17%and 101.51%,respectively.The study on cow indicated:there was no harmful influence by 50%alfalfa hays replaced by rape substrates in cows' diet on production performance,milk quality and serum biological parameters.The cost was obviously cut down and the economic returns was largely raised.