产酸性蛋白酶微生物的筛选及其在玉米淀粉生产中的应用

分别从土壤和泡菜中筛选到适合玉米淀粉湿法加工浸泡条件(50℃,pH值3.5～5)的微生物,经形态学及分子生物学鉴定,初步确定该菌株为烟曲霉(Aspergillas fumigates);提取发酵液中的酸性蛋白酶粗酶进行酶学性质研究,发现该酶在50℃,pH值3.5～5下仍保持较高的稳定性;将发酵液应用于玉米淀粉湿法浸泡工艺中,优化的玉米浸泡条件为:浸泡温度50℃、乳酸含量0.5%、SO2含量0.08%,初次浸泡12 h,然后添加12%发酵液浸泡10 h。新工艺减少了环境污染,浸泡时间缩短了26 h,更有利于生产。

Screening of Microorganisms for Production of Acid Protease and Its Application in Production of Corn Starch

Microorganisms were screened from garden soil and pickles to meet the requirements conditions for the wet corn starch process,which are at 50℃ and pH3.5~5.We did identification of morphological and molecular biology of the microorganisms.The microorganism was initially identified as Aspergillus fumigatus(A.fumigates strain).We studied the enzyme properties of crude enzyme of acid protease extracted from the fermentation broth,and the results suggested that the crude enzyme still maintained a high stability at 50 ℃ and pH 3.5~5.The fermentation broth was applied in the production of corn starch to optimize the conditions of corn soaking.The optimum soaking conditions for corn steeping processing were: steeping water temperature 50℃,lactic acid 0.5%,SO2 0.08%,initial immersion 12h,add 12% soaking broth 10h.The technology can reduce environmental pollution,short soaking time of 26h,so it is more conducive to apply to the industry production.