Aerobic fed-batch cultures were studied as a means of suppressing the production of lactate, which inhibits the growth of lactic acid bacteria (LAB). LAB produce lactate via lactate dehydrogenase (LDH), regenerating nicotinamide adenine dinucleotide (NAD⁺) consumed during glycolysis. Therefore, we focused on NADH oxidase (NOX), employing oxygen as an electron acceptor, as an alternative pathway to LDH for NAD⁺ regeneration. To avoid glucose repression of NOX and NAD⁺ consumption by glycolysis exceeding NAD⁺ regeneration by NOX, glucose was fed gradually. When Lactococcus lactis MG 1363 was aerobically fed at a specific growth rate of 0.2 h⁻¹, the amount of lactate produced per amount of grown cell was reduced to 12% of that in anaerobic batch cultures. Metabolic flux analysis revealed that in addition to NAD⁺ regeneration by NOX, ATP acquisition by production of acetate and NAD⁺ regeneration by production of acetoin and 2,3-butanediol contributed to suppression of lactate production.

研究了有氧分批补料培养作为抑制乳酸产生的一种方法，乳酸的产生抑制了乳酸菌（LAB）的生长。LAB通过乳酸脱氢酶（LDH）产生乳酸，从而再生糖酵解过程中消耗的烟酰胺腺嘌呤二核苷酸（NAD ⁺）。因此，我们集中于NADH氧化酶（NOX），采用氧作为电子受体，作为LDH进行NAD ⁺再生的替代途径。为了避免糖酵解抑制NOX和NAD ⁺消耗的葡萄糖，使之超过NAD ⁺ NOX的再生，逐渐添加葡萄糖。当以0.2 h ^-1的特定生长速率对乳酸乳球菌MG 1363进行有氧喂养时，每单位生长细胞产生的乳酸量减少至厌氧分批培养的12％。代谢通量分析表明，除了通过NOX进行NAD ⁺再生外，通过乙酸盐的生产获得ATP以及通过生产乙酰丁二酸和2,3-丁二醇的NAD ⁺再生也有助于抑制乳酸的产生。