不同气体环境对益生菌Bifidobacterium lactis V9生长的影响

Effects of air condition on the viability of probiotic bacteria: Bifidobacterium lactis V9

摘要:

Bifidobacterium lactis V9 (B. lactis V9)是一株具有良好益生特性且遗传稳定的益生菌, 工业化生产环境中气体组成关系着益生菌活菌数量, 进而影响其益生功效。【目的】研究不同气体环境对B. lactis V9生长及代谢的影响。【方法】在固体MRS培养基、液体MRS培养基及巴氏杀菌脱脂乳接种B. lactis V9, 于不同的气体环境中培养。【结果】在固体MRS培养基上, B. lactis V9在混合气体(N2:H2:CO2= 80:10:10)环境中菌落形成较氮气环境(N2: 99.99%)多, 在空气环境(N2:O2≈79:21)中菌落形成极少。B. lactis V9在MRS液体中培养24 h, 混合气体环境下其活菌数(9.11±0.11 log CFU/mL)显著高于空气环境下的活菌数(8.04±0.10 log CFU/mL) (P<0.01), 在混合气体环境下B. lactis V9代谢生成的乙酸和乳酸量分别为12.79±0.86 mmol/L 和11.99±0.73 mmol/L, 显著高于在空气环境中生成量0.65±0.07 mmol/L和2.75±0.57 mmol/L (P<0.01), 乙酸/乳酸比值分别为1.06:1和0.24:1。B. lactis V9在巴氏杀菌脱脂乳中发酵18 h, 混合气体环境下pH值(4.48±0.07)显著低于空气环境下的pH值(5.03±0.12) (P<0.01), 混合气体环境下其活菌数(9.02±0.15 log CFU/mL) 显著高于空气环境下的活菌数(8.53±0.08 log CFU/mL) (P<0.01)。混合气体和空气环境下发酵脱脂乳产生的乙酸和乳酸量分别为60.52±2.30 mmol/L、5.17±1.02 mmol/L和16.86±0.34 mmol/L、5.92±0.81 mmol/L, 乙酸/乳酸的值分别为11.71:1和2.85:1。【结论】在N2:H2:CO2=80:10:10混合气体环境下有利于B. lactis V9在液体MRS和脱脂乳中生长, 其活菌数可以增加0.5?1个数量级。这一研究结果也可为B. lactis V9益生菌发酵乳的生产和产品中B. lactis V9活菌培养计数提供指导。

Abstract:

Bifidobacterium lactis V9 (B. lactis V9) has been demostrated as a probiotic with well properties and stable genetics. The gas composition in environment of industrial manufacturation is positively associated with viable numbers of probiotic and nextly have influence on probiotic properties. [Objective] The influence of different gas environment on the growing of B. lactis V9. [Methods] By MRS agar plate, liquid MRS medium and pasteurized skim milk inoculated with B. lactis V9. [Results] On the MRS agar plate, the numbers of B. lactis V9 forming colonies under mixed gas environment (N2:H2:CO2=80:10:10) was more than nitrogen gas environment (N2: 99.99%) and few colonies formed under normal air environment (N2:O2≈79:21). In the MRS liquid medium for 24 h, the viable counts under mixed gas were 9.11±0.11 log CFU/mL which was significantly higher than growing in normal air condition with 8.04±0.10 log CFU/mL (P<0.01). Moreover, the acetate and lactate production under mixed gas condition were respectively significantly higher than normal air condition (12.79±0.86 mmol/L VS 11.99±0.73 mmol/L, 0.65±0.07 mmol/L VS 2.75±0.57 mmol/L, P<0.01). In addition, the acetate/lactate molar ratio was 1.06:1 and 0.24:1, respectively. After 18 h of pasteurized skim milk fermentation, the reduced pH of fermented milk under mixed gas condition was significantly lower than normal air condition (4.48±0.07 VS 5.03±0.12, P<0.01). The viable counts under mixed gas were 9.02±0.15 log CFU/mL which was significantly higher than growing in normal air condition with 8.53±0.08 log CFU/mL (P<0.01). The acetate and lactate production under mixed gas condition vs. normal air condition in fermented milk were 60.52±2.30 mmol/L and 5.17±1.02 mmol/L VS 16.86±0.34 mmol/L and 5.92±0.81 mmol/L, repectively. The acetate/lactate molar ratio was 11.71:1 and 2.85:1, repectively. [Conclusion] These study suggested that mixed gas condition with N2:H2:CO2=80:10:10 was beneficial for B. lactis V9 growing in liquid medium and pasteurized skim milk fermentation increased by 0.5?1 grade of viable counts during the same time. It can provide instruction for preparation of probiotic fermented milk and viable bacterial counting of B. lactis V9.