摘要
Among the lactic acid bacteria isolated from beer at different stages of elaboration, Pediococcus pentosaceus was the predominant species and the only that used glycerol as sole carbon source. Its utilization was studied in CAg strain growing on glycerol or on glycerol and limited concentration of glucose. Glycerol kinase and glycerol dehydratase pathways were responsible for glycerol degradation. On glycerol alone, the enzymatic activities of both pathways were expressed simultaneously and after glycerol consumption, the main products were acetate, 2,3-butanediol (2,3-BD) and 1,3-propanediol (1,3-PD). When the carbon sources were glycerol and glucose, glycerol was firstly degraded by the reductive pathway and after glucose consumption the activities of the glycerol kinase pathway were expressed. In this condition, glycerol was transformed into lactate, acetate, 2,3-BD and 1,3-PD. According to the enzymatic activities and fermentation balances, the production of acetate, providing ATP, can be correlated to lactate degradation, and the NAD required by these transformations could be obtained by the formation of 1,3-PD and 2,3-BD. Glycerol degradation should be correlated with the sensitivity of a beer to bacterial spoilage, and P. pentosaceus CAg considered as spoilage strain because it produces high volatile acidity and aroma compounds from glycerol conferring unacceptable flavour to beer.
摘要译文
从啤酒中分离出的不同阶段的乳酸菌中，戊糖片球菌是以甘油为唯一碳源的唯一优势菌种。在甘油或甘油生长的CAg菌株和有限的葡萄糖浓度下研究其利用。甘油激酶和甘油脱水酶途径负责甘油降解。单独甘油时，主要产物为乙酸，2,3-丁二醇（2,3-BD）和1,3-丙二醇（1,3-PD）。当碳源是甘油和葡萄糖时，甘油首先被还原途径降解，葡萄糖消耗后则表达甘油激酶途径的活性。在这种条件下，甘油转化为乳酸盐，乙酸盐，2,3-BD和1,3-PD。根据酶活性和发酵平衡，乙酸的产生，提供ATP，可以与乳酸降解相关，并且这些转化所需的NAD可以通过形成1,3-PD和2,3-BD而获得。甘油的降解应该与啤酒对细菌腐败的敏感性相关。戊糖乳杆菌CAg被认为是腐败菌株，因为它产生高甘油的挥发性酸度和芳香化合物，赋予啤酒不可接受的风味。
M.G.Vizoso Pinto;S.E.Pasteris;A.M.Strasser de Saad[1];. Glycerol catabolism by Pediococcus pentosaceus isolated from beer[J]. Food Microbiology, 2004,21(1): 111-118