变温培养对乳酸菌高密度培养的影响

Effect temperature-shift strategy on high density culture of Lactic acid bacteria

研究了单一温度培养模式和变温培养模式对乳酸菌发酵活力和生物量的影响。生物量采用活菌计数法测定,发酵活力采用单位时间发酵基质酸度变化测定。结果表明,在乳酸球菌St98的高密度培养过程中采用单一温度(33～42℃)培养时,当培养温度为39°C时,生物量达到最大值3.6×109mL-1,当培养温度为37°C时,发酵活力达到最大值1.22(pH/h)。采用两阶段的温度控制方式,发酵初期(0～3.15 h)采用39℃进行发酵,在发酵进行3.15 h以后,采用35℃进行发酵,到达稳定期的时间为5.75 h,最大细胞生物量为4.7×109 mL-1,最高发酵活力为1.39(pH/h),与单一温度发酵相比,乳酸球菌St98的生物量和发酵活力均有所提高。

Lactic acid bacteria have commonly been used in Fermented Food. Biomass and activity of lactic acid bacteria are important for starter. Temperature is one of the most important environmental factors for cell growth. This experiment purpose lies in studying influence of model-based single temperature and temperature-shift on biomass and activity of lactic acid bacteria. The biomass was measured by colony counting method, the activity was measured by acidity change per unit time. St98 at various temperatures, ranging from 25 to 35℃, were studied. Activity and biomass reached 1.22（pH/h） and 3.6×10^9mL^-1, respectively at 37℃ and 39 ℃, which were higher than those at other temperatures. Based on these results, a two-stage temperature control strategy was developed in which 39℃ was used for fermentation for the first 3.15 h and the temperature was switched to 35℃ after 3.15 h. Using this temperature-shift strategy, the maximal activity and biornass reached 1.39 （pH/h） and 4.7×10^9mL^-1, respectively. The activity and biomass obtained by the strategy was higher than those in single temperature-control experiments.