一株能够利用血红素进行有氧呼吸的乳酸乳球菌

Lactococcus lactis capable of respiring in the presence of heme

摘要:

【目的】乳酸乳球菌在呼吸状态下，生长速度快，生物产量大，是改善发酵剂生产效率的潜在途径之一，本研究旨在观察由传统乳制品中分离得到的乳酸乳球菌在血红素存在状态下有氧呼吸情况以及代谢的变化。【方法】对本实验室保藏的12株乳酸乳球菌进行有氧培养实验，比较其生物量和代谢产物的差异。观测在4℃下储藏30 d后的活菌数差异。【结果】筛选出一株在血红素存在条件下进行有氧呼吸的菌株KLDS 4.0316，与没有添加血红素的原菌株相比生物量增长了50%，在4℃储藏30 d后，添加血红素并振荡的活菌数依然维持在108 CFU/mL，而未添加血红素未振荡检测不到活菌。在血红素存在下，KLDS 4.0316代谢产物发生了变化，与没有添加血红素的原菌株相比乳酸产量减少了48%。【结论】KLDS 4.0316在血红素存在条件下能够进行有氧呼吸，乳酸产生减少，生物量增加。

Abstract:

[Objective] Lactococcus lactis undergoing respiration has fast growth rate and relatively high biomass, which is the one of the potential way of improving the production efficiency of starter. In this study, the respiration situation and metabolism changes of Lactococcus lactis strains in the presence of heme were investigated. [Methods] Twelve strains of Lactococcus lactis were examined with aerobic cultivating test. The difference of biomass and metabolites among strains were compared. Furthermore, the survival rate at storage at 4℃ for 30 days was also compared by testing their viable cell count. [Results] A strain of Lactococcus lactis coded as KLDS 4.0316 could respire in the presence of heme. The biomass of KLDS 4.0316 cultivated in the present of heme increased by 50%. After being stored at 4℃ for 30 days, the strain cultivated under the condition without oxygen and heme was totally dead, whereas the viable cell count of strain cultivated with oxygen and heme remained 108 CFU/ml. Production of lactic acid decreased by 48%, compared with the strain cul-tivated in the absent of heme. [Conclusion] KLDS 4.0316 can undergo respiration in the present of heme, and the pro-duction of lactic acid decreased while the biomass increased.