Screening Of The Thermotolerant Alcohol Yeast Strain And Study Of Fermentation Characteristic

In this study,116 yeast strains were isolated from various materials using selective enrichment medium method, such as from the traditional Chinese liquor matrix, of which 58 have excellent ability of alcohol fermentation. After two-grade selection, from which one during 33 ~ 42℃grow well and have good performance of the alcohol fermentation yeast strains XG-1, 40℃liquid shake flask culture conditions, XG-1 strains the number of viable the total number of bacteria than Thermal Resistance Alcohol Instant ADY (TRADY) high 15%. XG-1 strains used in ethanol fermentation of cassava, 18% starch concentration, 33℃, the alcohol concentration of up to 12.5V / V, starch 90.91% utilization can be achieved with TRADY considerable strain the ability of alcohol fermentation, and in 42℃for XG-1 strains fermentation , alcohol content higher than 20% of strains TRADY.XG-1 for the 18S rRNA gene amplification and sequence analysis of other characteristics of six more strains also carried out sequence analysis, including the WLY-2, J-2, GAXQ-1, GAXQ-2, GATQ-1, GATQ-2.Nitrogen assimilation tests showed that the strains can not assimilate potassium nitrate. Comparison of the strain results of carbon assimilation and carbohydrate fermentation test results, were "The yeasts: a taxonomic study" to describe the characteristics of yeast and sequence analysis, 3 of which can be drawn from XG-1, WLY-2, J-2 for the case of Saccharomyces cerevisiae, GAXQ-1, GAXQ-2, GATQ-2 for the Issatchenkia orientalis, GATQ-1 for Pichia norvegensis, and identification of the results of carbohydrate basically the same. The growth of XG-1 and fermentation characteristics of a series of studies have been done, including the growth curve, the optimal growth pH, different starch raw material, different temperatures fermentation test, the temperature of fermentation, inoculum size and fermentation time of the orthogonal test to be: the impact of fermentation temperature of raw materials is a major factor in the rate of alcohol, followed by the fermentation time and the impact of inoculum. At the same time, the optimal conditions can be drawn for the 2.5% inoculum (initial bacterial counts for 0.1 million / ml), fermentation temperature is 33℃, fermentation time is 72h.Use 20% and 50% lees supernatant fluid to replace water reusing to test and regulate pH to around 6.0 required to liquefaction, and then keep the same conditions for saccharification, fermentation maturation of the various parameters as much as comparison, so back to the fermentation of alcohol use will not have any adverse effects. Using Candida utilis 1087 and Candida tropicalis 1254, the microbial fermentation of protein was produced, and its lees liquid in the removal of COD was explore, also with the compare of enzymes and glucoamylase complex role in the fermentation. Produce single cell protein with Candida yeasting, the protein can increase to 51.6%, and achieve 17.031% at the last. The entire lees COD elimination rate may achieve 39.5%, but the lees fluid supernate's COD elimination rate may achieve 53.74%.