Isolation of Aspergillus from Jiangxiang Liquor Fermentation Environment and Enzyme Secretion Stress Conditions of Aspergillus hennebergii

Abstract:

The ecological distribution of Aspergillus in the samples obtained at the key points of Jiangxiang liquor fermentation process in Maotai village and the effect of solid fermentation simulated by fresh bran medium on the growth of predominant strain Aspergillums hennebergii and the main stress conditions of glucoamylase and protease secretion were analyzed in this paper. One hundred and three strains were obtained and identified as A.niger，A.oryzae，A. terreus，A.tubingensis，A.flavus，A.hennebergii，A.fumigatus，A.niveus，A.candidus and Monascus，respectively. The suitable conditions for the growth and protease secretion of Aspergillums hennebergii were 50% water content of the fermentation substrate and the pH value of 3.5-4.0. The suitable growth temperature of Aspergillums hennebergii was 30~35 ℃，whereas the suitable enzyme secretion temperature was 32~35 ℃. High alcohol contents（>8%，v/w）inhibited the growth and enzyme secretion of Aspergillums hennebergii，while low alcohol contents（2%，v/w），lactose，and maltose promoted its growth and enzyme secretion. The salt of（NH3）4SO4 and NaNO2 and yeast could promote its growth，glucoamylase and protease secretion. Moreover，sorbose，sucrose and fructose could promote its glucoamylse secretion. The individual addition of sodium sulphate could promote its growth and enzyme production. Fresh bran，which was rich in carbon source，nitrogen source，inorganic salts and trace elements，could provide high-quality natural carrier for Aspergillums hennebergii growth and enzyme production. The application of Aspergillums hennebergii can satisfy the need of bilateral fermentation and flavor forming mechanism in traditional solid fermentation of liquor.