Screening,identification and enzyme production conditions optimization of a cellulase-producing yeast
In order to screen high cellulose-producing yeast,cellulose-producing yeasts were screened from the fermented grains of sauce-flavor(Jiangxiangxing)Baijiu by Rose Bengal Agar and Congo Red Medium,and the screened strains were identified by morphological observation,physi-ological and biochemical tests,and molecular biology technique.The tolerance was investigated and the enzyme production conditions were opti-mized.The results showed that a cellulase-producing strain JXJP-Y19 was screened,and the strain JXJP-Y19 was identified as Yarrowia lipolytica.The temperature,ethanol,and pH tolerance of the strain JXJP-Y19 were 39 ℃,8％(V/V),and 3,respectively,showing good tolerance to environmental stress.The optimal enzyme production conditions were as follows:bran as carbon source,cottonseed cake as nitrogen source,inoculum 1％,initial pH 6 and fermentation temperature 30 ℃.Under these optimal conditions,the activities of filter paper enzyme,exoglucanase and β-glucosidase pro-duced by the strain JXJP-Y19 were(0.913±0.025)U/ml,(1.272±0.025)U/ml and(0.937±0.030)U/ml,respectively,which were 2.15 times,1.81 times,and 1.94 times higher than before optimization.The strain JXJP-Y 19 showed good cellulase activity and could be used as a potential strain for cellu-lose bio-degradation utilization.
yeastscreeningidentificationcellulaseenzyme production conditions optimization
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