Isolation and Identification of Representative Fungi from Shaoxing Rice Wine Wheat Qu Using a Polyphasic Approach of Culture-Based and Molecular-Based Methods

Abstract

J. Inst. Brew. 113(3), 272-279, 2007Ribosomal intergenic spacer analysis (RISA) and traditional culture-based methods were employed to examine the fungal community of Shaoxing rice wine wheat Qu. Results showed that RISA profiles of total DNA exhibited nine distinguishable bands. By comparison, the RISA fingerprints recovered from enrichment media gave variable patterns containing fewer bands. Bands corresponding to five fungal species detected by RISA of total DNA were also observed in RISA fingerprints from enrichment cultures. A total of twenty-four pure cultures were isolated with media of potato dextrose agar (PDA), Czapek (CPK) and wheat Qu extraction (WQE). A total of eight, eighteen and eleven fungal species and 7.9 × 10 5 cfu /g Qu, 3.0 × 10 5 cfu /g Qu, and 3.9 × 10 6 cfu /g Qu, were isolated using PDA, CPK and WQE media, respectively. Predominance of each representative species did vary with the culture medium. Comparison of ITS sequences of excised RISA bands and recovered pure isolates with those in GenBank database revealed that the representative fungal species in wheat Qu were Absidia corymbifera, Saccharomyces cerevisiae, Rhizopus oryzae, Rhizomucor pusillus, Aspergillus oryzae, Candida tropicalis, Emericella nidulans, Clavispora lusitaniae, Aspergillus fumigatus, Aspergillus niger, Rhizopus microsporus, Pichia guilliermondii and Pichia anomala. Species of Saccharomyces cerevisiae, Candida tropicalis and Rhizopus oryzae detected in the original samples by analysis of RISA were not recovered in any of the three media. In addition, some species recovered from the enrichments were not detected by RISA analysis. Results obtained with culture-based or molecular-based methods clearly confirmed the importance of developing an integrated approach to gain a better understanding of the microbial community in wheat Qu.

The Influence of Yeast Strains on the Volatile Flavour Compounds of Chinese Rice Wine

“…Because some of the materials used in Chinese rice wine brewing are not sterile, higher pitching rates are traditionally used to ensure that the inoculated yeast strain is the dominant strain and finishes the fermentation. wheat Qu is a source of many enzymes such as amylase, glucoamylase and protease 13,27 . Raw materials are degraded by these enzymes, producing nutritional components for yeast growth and fermentation.…”

Changes in Volatile Compounds of Chinese Rice Wine Wheat Qu During Fermentation and Storage

“…Research has generally focused on the enzymes and microorganisms of wheat Qu 24,30 , and the flavor of wheat Qu is judged by its simple sensory description with the term "normal or no odor of wheat Qu". It is the volatile compounds of wheat Qu however, that are the most important factors which influence the flavor of Chinese rice wine 23 , and for this reason it was important to analyze and characterize the volatile compounds from wheat Qu.…”

“…Wheat Qu is then incubated under spontaneous conditions for at least 15 days and stored for several months before being used to make Chinese rice wine. As a result of fermentation, wheat Qu is rich in various microorganisms such as Absidia corymbifera, Rhizopus oryzae, Rhizomucor pusillus, 30 . A wide variety of enzymes including amylases, glucoamylase, proteases, phytase and phosphatase also accumulate in the wheat Qu during fermentation.…”

Analysis of characteristic flavour compounds in Chinese rice wines and representative fungi in wheatQusamples from different regions

“…It is reported that the representative microorganisms in wheat Qu are Absidia corymbifera, Rhizomucor pusillus, Aspergillus fumigatus, Aspergillus orgyze, Rhizopus oryzae and a small amount of Penicillium sp., yeasts and bacteria (6)(7)(8). Wheat Qu provides the main microorganisms and the complex enzyme systems during a Chinese rice wine fermentation.…”

“…However, there is little research on the formation mechanism of the flavour compounds and the microorganisms in wheat Qu that directly affect the rice wine flavour. In general, the main flavour compounds in various rice wines (8,14,15) and Japanese sake (4,(16)(17)(18) are generated by the metabolism of the fungi. The objective of this study was to compare the volatile flavour compounds of the rice wines fermented with different kinds of wheat Qu samples, and to analyse the main species differences in the fungi.…”