乳酸菌风味代谢物质的基因调控

Gene regulation to lactic acid bacteria for increasing production of flavor metabolite

摘要:

乳酸菌的主要风味代谢物质包括丁二酮,乙醛以及各种氨基酸。利用基因工程和代谢工程的相关技术提高乙醛和丁二酮产量,是当前乳酸菌研究的热点之一。乙醛的代谢调控主要是针对丝氨酸羟甲基转移酶的表达进行调控,或是针对丙酮酸脱羧酶和NADH氧化酶的表达采用联合调控策略;而丁二酮的代谢调控则主要集中于乳酸脱氢酶、NADH氧化酶、α-乙酰乳酸合成酶和α-乙酰乳酸脱羧酶中任意两种关键酶基因间的联合调控,并且存在进行乳酸脱氢酶,α-乙酰乳酸合成酶和α-乙酰乳酸脱羧酶3种关键酶基因联合调控的可行性。

Abstract:

The major flavor substances Lactic acid bacteria produced include the buttermilk aroma butanedione, the yoghurt flavor acetaldehyde and the amino acid. Metabolic engineering in LAB had focused primarily on rerouting of pyruvate metabolism towards butanedione or acetaldehyde to improve the flavor of fermented milk, which has considerable economic value. The typical yogurt flavor is caused by acetaldehyde produced through many different pathways. The attention was focused on one specific reaction for acetaldehyde formation catalyzed by serine hydroxymethyltransferase, which encoded by the glyA gene. In addition, the efficient conversion of glucose into acetaldehyde was achieved by over-expression of pyruvate decarboxylase and NADH oxidase in LAB. The concentration of acetaldehyde derived from this regulation is higher than the other strategy. As for the regulation of butanedione, it was focused on combinating inactivation of α-acetolactate decarboxylase with low lactate dehydrogenase activity, or with overproduction of NADH-oxidase, or with overproduction of α-acetolactate synthase. Then the possibility of co-regulation with certain three kinds of enzyme above was recommended.