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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。
Bifidobacterium lactis V9 (B.lactis V9) is a genetically stable probiotic with good probiotic properties. The gas composition in industrialized production is related to the number of viable probiotics, which in turn affects its probiotic efficacy. 【Objective】 To investigate the effects of different gaseous environments on the growth and metabolism of B.lactis V9. 【Method】 B.lactis V9 was inoculated on solid MRS medium, liquid MRS medium and pasteurized skim milk, and cultured in different gas environments. 【Result】 The results showed that colony formation of B.lactis V9 in mixed medium (N2: H2: CO2 = 80: 10: 10) was more than that in nitrogen environment (N2: 99.99% : O2≈79: 21), there is very little colony formation. B.lactis V9 was cultured in MRS liquid for 24 h, its viable count (9.11 ± 0.11 log CFU / mL) in mixed gas environment was significantly higher than that in air (8.04 ± 0.10 log CFU / mL) (P <0.01). The amounts of acetic acid and lactate produced by B.lactis V9 in mixed gas environment were 12.79 ± 0.86 mmol / L and 11.99 ± 0.73 mmol / L, respectively, which were significantly higher than those in the air environment of 0.65 ± 0.07 mmol / L and 2.75 ± 0.57 mmol / L (P <0.01). The ratio of acetic acid / lactate was 1.06: 1 and 0.24: 1, respectively. B.lactis V9 was fermented in pasteurized skimmed milk for 18 h. The pH of mixed solution was 4.48 ± 0.07, which was significantly lower than that of air (5.03 ± 0.12) (P <0.01) The viable count (9.02 ± 0.15 log CFU / mL) was significantly higher than that in the air (8.53 ± 0.08 log CFU / mL) (P <0.01). The amounts of acetic acid and lactate produced by fermented skim milk under mixed gas and air environment were 60.52 ± 2.30 mmol / L, 5.17 ± 1.02 mmol / L and 16.86 ± 0.34 mmol / L, 5.92 ± 0.81 mmol / L respectively. The value of acetic acid / Respectively 11.71: 1 and 2.85: 1. 【Conclusion】 The growth of B.lactis V9 in liquid MRS and skimmed milk is favorable in the mixed gas of N2: H2: CO2 = 80: 10: 10, and the viable count can be increased by 0.5-1 order of magnitude. The results of this study also provide guidance on the production of B. lactis V9 probiotic fermented milk and the count of viable B.lactis V9 cultures in the product.