Maicas Sergi, Ferrer Sergi, Pardo Isabel
Departament de Microbiologia i Ecologia, Facultat de Biologia, Universitat de València, C/Dr Moliner, 50, Burjassot, València, Spain 46100-E1.
Microbiology (Reading). 2002 Jan;148(Pt 1):325-332. doi: 10.1099/00221287-148-1-325.
Oenococcus oeni (formerly Leuconostoc oenos) can perform malolactic fermentation, converting L-malate to L-lactate and carbon dioxide, in wines. The energy and redox potential required to support the growth of the micro-organism are supplied mainly by the consumption of carbohydrates via the heterolactic pathway. In the first steps of hexose metabolism two molecules of NAD(P)(+) are consumed, which must be regenerated in later reactions. The aim of this work was to test if aerobic growth of O. oeni promotes higher cell yields than anaerobic conditions, as has been shown for other lactic acid bacteria. O. oeni M42 was found to grow poorly under aerobic conditions with glucose as the only carbohydrate in the medium. It was demonstrated that O(2) inactivates the enzymes of the ethanol-forming pathway, one of the two pathways which reoxidizes NAD(P)(+) cofactors in the heterolactic catabolism of glucose. These results suggest that the regeneration of cofactors is the limiting factor for the aerobic consumption of glucose. When external electron acceptors, such as fructose or pyruvate, were added to glucose-containing culture medium the growth of O. oeni was stimulated slightly; fructose was converted to mannitol, oxidizing two molecules of NAD(P)H, and pyruvate was transformed to lactate, enabling the regeneration of NAD(+). The addition of cysteine seemed to suppress the inactivation of the ethanol-forming pathway enzymes by O(2), enabling glucose consumption in aerobic conditions to reach similar rates to those found in anaerobic conditions.
酒酒球菌（以前称为酒类酒球菌）能够在葡萄酒中进行苹果酸 - 乳酸发酵，将L - 苹果酸转化为L - 乳酸和二氧化碳。支持该微生物生长所需的能量和氧化还原电位主要通过异型乳酸途径消耗碳水化合物来提供。在己糖代谢的第一步中，消耗两分子的NAD(P)(+)，这些必须在后续反应中再生。这项工作的目的是测试酒酒球菌的有氧生长是否比厌氧条件下能产生更高的细胞产量，正如其他乳酸菌所显示的那样。发现酒酒球菌M42在有氧条件下以葡萄糖作为培养基中唯一的碳水化合物时生长不佳。结果表明，O₂会使乙醇形成途径的酶失活，乙醇形成途径是葡萄糖异型乳酸分解代谢中使NAD(P)(+)辅因子再氧化的两条途径之一。这些结果表明，辅因子的再生是葡萄糖有氧消耗的限制因素。当向含葡萄糖的培养基中添加外部电子受体，如果糖或丙酮酸时，酒酒球菌的生长会受到轻微刺激；果糖被转化为甘露醇，氧化两分子的NAD(P)H，丙酮酸被转化为乳酸，从而使NAD⁺得以再生。添加半胱氨酸似乎可以抑制O₂对乙醇形成途径酶的失活作用，使有氧条件下的葡萄糖消耗速率达到与厌氧条件下相似的水平。
