| The research aimed at investigating the bio-conversion of corn straw with neurospora sitophila.We applied solid state fermentation to improve its nutritive value as feed.The main research contents were as follows:First,we identificated ligninase produced by neurospora sitophila.The cellulase(CMC),filter paper enzyme(FPA)and ligninase during fermentation were determined by method of DNS,ABTS,veratrol,2,6-DMP.The content of crude fiber(CF)was measured by a filter bag method.The results showed as follows:the aniline blue fading reaction and guaiacol chromogenic reaction showed that neurospora sitophila could produce ligninase,the curve of enzyme activity showed that the laccase activity was 0.10 IU·mL-1 at the 5th day and the lignin peroxide was 7.00 IU·mL-1 at the 6th day,and the activity of manganese peroxidase was 0.70 IU·mL-1 at the 3rd day.Both the activity of the cellulase and filter paper enzyme reached the maximum values of 109.60 IU·mL-1 and 21.72 IU·mL-1,respectively,at 84 h;CF,NDF,and ADF decreased by 20.60%,10.78%and 20.28%,respectively,after fermentation.The content of lignin(ADL)was 7.43%after 4 days of fermentation,which was significantly lower than the control group(P<0.05).Second,using single factor analysis and orthogonal tests to optimize the conditions of extraction of carotenoids by acid-thermal wall breaking method.The results showed that the optimal extraction conditions were as follows:1 mol·L-1 hydrochloric acid,3 mL/10mg hydrochloric acid,shaking in a constant-temperature shaker for 35 min,boiling water bath for 8 min,extraction with 20mL acetone,the absorbance of carotenoids was 0.92.The extraction efficiency of carotenoids was greatly improved compared with that before optimization(P<0.01).Third,using single factor analysis and orthogonal tests investigates the effects of carotenoid production through many factors,the results showed that the optimum conditions were:the dry corn straw was 10g,and the corn flour,urea and magnesium sulfate were added to water,and reached choncentration of 9 g·L-1,14 g·L-1 and 0.1 g·L-1,respectively.The age of inoculation was 20h,the amount of inoculation was 8%,fermented 84h at 28?.The yield of carotenoids reached 75.76 mg·Kg-1 that was highest level.Fourth,carotenoids produced by fermentation was analyzed with TLC,UV full wavelength scanning and HPLC.The results showed that the maximum absorption wavelength of the crude extract of carotenoids and the acetone solution of ?-carotene were 464nm and 454nm,respectively.The yield of carotenoids was 75.78 mg·kg-1,?-carotene accounted for 14.78%.The carotenoids stability showed that the free pigment was unstable in sunlight and ultraviolet light,50?,oxidant H2O2,strong acid and strong alkali,however,the deoxidizer had a protective effect on it.Carotenoids was very stable to light,heat,alkali and oxidant under the protection of the spore wall,but it was unstable under strong acid conditions.Fifth,analysis of nutritional components,the results showed that the true protein content increased very significantly(P<0.01),crude fiber content decreased significantly after fermentation(P<0.01),the change of calcium and phosphorus content were not significant(P>0.05),and the content of carotenoids was 3.1 times as high as that before optimization.The above results indicated that corn straw could be transfereed by means of solid fermentation through neurospora sitophila,which greatly improved the feeding value of straw,and also laid foundations for the further development of carotenoids functional bio-feed. |
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