Research On High Active Cellulase From Rice Straw And Strains Of Different Genotypes

Cellulosic ethanol was currently the main development direction of fuel ethanol.Cellulose is the major constituent of rice straw,China was rich in rice straw resources,It was a very promising technology to make conversion of rice straw into fuel ethanol in the resolution of energy problem,realization of grain's economy and substitution.Due to differences in the structure and chemical composition of rice straw,the conversion efficiency of cellulosic ethanol has been influenced by a certain degree.49 strains and 443 rice straw of different genotypes were selected for cellulase activity research,and the production conditions of cellulase and simultaneous saccharification and fermentation of rice straw were further optimized.The main results were as follows:(1)Two high active cellulase-producing strains A 19 and A 27 were screened from 49 strains by Congo red staining and enzyme assay.Cellulase produced by A 19 had harmonious proportions and higher activity,its filter paper enzyme activity(5.214 IU/g),CMC cellulase activity(11.007 IU/g),cotton cellulase activity(0.834 IU/g),which were respectively 2.02,1.31 and 2.70 times as high as strain A 49(control).The ?-glycosidase cellulase activity of A 27 was 8.990 IU/g,which was 2.15 times as high as A49(control).(2)Appling high cellulase-producing strain A 19 and 443 rice straw of different genotypes in cellulase production test by solid-state fermentation.A high-quality straw of rice "2B948" which could produce cellulase with the highest activity was selected,its filter paper enzyme activity was 8.235 IU/g,2.06 times as high as recommended variety SHUHUI 527(control).(3)Solid-state fermentation conditions for cellulase production of A 19 and A 27 were optimized by single factor tests and response surface method,the research results showed that with straw of rice"2B948" as the substrate,the optimum conditions that A 19 produces cellulase was described as below:the ratio of straw powder to wheat bran was 5:0,ammonium nitrate as nitrogen source and nitrogen content was 0.6%,the ratio of material to water was 1:2,the cultivation temperature was 28? incubation time was 4.3 days,medium initial pH was 6.24,inoculation amount was 4%.Under these conditions,the filter paper activity was 9.282 IU/g.The optimum conditions that A 27 produces cellulase was described as below:the ratio of straw powder to wheat bran was 5:0,peptone as nitrogen source and nitrogen content was 0.9%,the ratio of material to water was 1:2,the cultivation temperature was 36.4?,incubation time was 6 days,medium initial pH was 3.16,inoculation amount was 10%.Under these conditions,the ?-glycosidase cellulase activity was 63.950 IU/g.(4)Appling yeast,straw of rice "2B948",cellulase from A 19 and A 27 in fuel ethanol production.The conditions of simultaneous saccharification and fermentation were optimized by single factor and orthogonal test.The results were as follows:pretreated straw powder wtih 5%NaOH solution,the initial pH of fermentation medium was 5.0,incubation time was 3 days,the cultivation temperature was 35?,the ratio of P-glycosidase to FPA was 1.5,inoculation amount of yeast was 15%.Under these conditions,the concentration of ethanol was 3.8 mg/mL,the conversion efficiency from rice straw to ethanol was 27.1%.