Screening Of Thermophilic Strain And Research On Application Performance In High Temperature Daqu

The microflora analysis of Baiyunbian high-temperature Daqu was studied in this paper, two high enzyme activities thermophilic strains were screened by enzyme activity analysis, and then the optimization of fermentation conditions and application performance were studied in this paper. The research results are as follows:1) This test applied microbiological ways to isolate and differentiate the microbe from autumn and spring high-temperature Daqu, the results as follows: The amount of bacteria is 5.60×10~5 cfu/g Daqu in the spring sample, and Bacillus occupied a dominant position; the saccharomyces was not detected; the quantity of mould is 7.30×10~2 cfu/g Daqu, the Mucor and Aspergillus occupied dominant position; the actinomycetes can not be detected. However, the quantity of bacteria in autumn sample is 1.40×10~5 cfu/g Daqu, less than spring sample, and Bacillus occupied a primary position; the quantity of saccharomyces is 2.30×10~2 cfu/g Daqu, the Saccharomyces occupied dominant position; the total number of mould is 5.50×10~2 cfu/g Daqu, larger than spring sample, the Mucor occupied an important position; the actinomycetes can not be detected.2) Ten anti-high-temperature strains were selected from high temperature Daqu, according to plate screening and conical flask screening, we obtained a strain of higherα-amylase producing capability, the physico-chemical identification result is Paenibacillus polymyxa, the survival rate reaches to 99.0 U/g; a strain of higher glucoamylase producing capability, the result is Paenibacillus polymyxa, the survival rate reaches to 2708.5 U/g; a strain of higher acid protease producing capability, the result is Bacillus licheniformis, the survival rate reaches to 1270.1 U/g.3) By studying condition optimization under solid state fermentation of the thermophilic strain, its optimum conditions to produce enzyme were found. A strain of higherα-amylase producing capability: the carbon source is bran; the nitrogen source is bean; the initial pH is 7.0;the culture temperature is 45℃,the time is 54h.The enzyme activity reaches to 176.2 U/g after condition optimization. A strain of higher glucoamylase producing capability: the carbon source is bran; the nitrogen source is bean; the initial pH is 6.0;the culture temperature is 50℃,the time is 54h.The enzyme activity reaches to 2998.6 U/g after condition optimization. A strain of higher acid protease producing capability:the proportion of carbon to nitrogen is 1:0.8, the initial pH is 5.0;the culture temperature is 45℃,the time is 52h,the inoculum size is 7%. The enzyme activity reaches to 1420.2 U/g.4) According to imitate the winery solid state fermentation in the laboratory, to analysis the influence from superior strain to liquor initially. The results about base liquor indicate that total acid and ester and alcohol strength are higher than ordinary base liquor. Meanwhile, the flavor substances in the superior base liquor are more than those in other base liquors.