Cloning and identification of rutin-degrading enzyme genes from Aspergillus niger in wheat Qu

Abstract

Tartary Buckwheat Huangjiu, one of the oldest wines in China, has unique health-promoting properties. One of its specific ingredients is rutin, which has antioxidative and anti-ageing activities and plays important roles in the treatment of human diseases. During Tartary buckwheat Huangjiu brewing, however, rutin is degraded by fungi in wheat Qu, thereby leading to a decrease in the wine's nutritional value. The consequent aim of this study was to identify effective rutin-degrading fungi and degrading enzyme genes in the Tartary buckwheat Huangjiu brewing process. Among these fungi isolated from wheat Qu, only Aspergillus niger exhibited rutin-degrading ability. Following protein purification, SDS-PAGE, mass spectrometry, Blast analysis and clone verification, we ultimately identified glucoamylase and α-L-rhamnosidase encoding genes were related to rutin degradation. To our knowledge, this is the first report of rutin-degrading enzyme genes in Tartary buckwheat Huangjiu. Our results provide insights for regulating the nutritional value of Tartary buckwheat Huangjiu.