Screening And Identification Of Microbe Inducing Wort Turbidity

The barley was easily infected by the microorganism in the process of growth, harvestingand storage, such organisms covered a variety of species including the bacteria, filamentousfungi and yeasts. The dormant microorganism population present in barley would be activatedin steeping and germination process. The favorable conditions suitable for malting also enablethe contaminated microorganism to rapidly multiply themselves and may eventually lead to aserious devastation to the malt quality, such as wort turbidity.This paper aimed to investigate the microbial factors which affected the EBC congresswort turbidity. A fungal strain was screened from the Australia barley Gairdner, which wasconsidered as the most influential microorganism contributing to the enhanced wort turbidityand prolonged filtration time. Based on the morphology detection and sequence analysis of26S rDNA domain gene, the sequence showed complete homogeneity with the large rRNAsubunit of the controlled strain Aspergillus Flavus AB363745.1and the strain was identifiedas Aspergillus Flavus. A remarkably turbidity-induced protein secreted from AspergillusFlavus was isolated and purified with Sephadex G-25and DEAE-cellulose DE-52chromatographic method. The80kDa subunit protein determined by SDS-PAGE analysiscould lead to a39.2%increase of the EBC congress wort turbidity at a concentration of0.2mg/l, compared with that of the control wort without addition of the purified fungal protein.