为提高餐厨垃圾水解液发酵产油脂量,探究其发酵生产规律,以Saccharomyces cerevisiae As2.516为供试菌株,以初始餐厨垃圾水解液加入量90%(V/V)、接种量10%(V/V)、初始pH值6、培养温度30℃、搅拌速率180r/min、通气量2.5L/min、发酵周期10d为基础发酵条件进行1L发酵罐批式发酵。实验结果表明:scerevisiae As2.516发酵过程中菌体生物量的积累呈一条S型曲线,油脂的生产表达与菌体的生长有紧密关联性。基于Logistic方程、Luedeking-Piret方程和物料平衡计算分别构建了该菌株的茵体生长、油脂产物生成、底物还原糖消耗3个分批发酵动力学模型,其中菌体生长动力学模型为:dx/dt=1.0241x(1-x/13.05)、底物还原糖消耗动力学模型为:ds/dt=0.4787dx/dt+0.0348x+0.1055dp/dt、油脂产物生成动力学模型为:dp/dt=0.2979dx/dt+0.00406x,所构建动力学模型的计算值与实验值拟合效果良好,其相关系数R2分别为0.9979、0.9957和0.9565,模型能揭示餐厨垃圾水解液培养菌体产油脂发酵过程中菌体生长、油脂合成以及底物还原糖消耗的基本特征。
In order to increase the production of microbial oils and indicate its regular pattern during fermentation process, Saccharomyces cerevisiae As2.516, was used to set up the kinetics models based on the optimal fermentation conditions: the initial addition of hydrolysis liquid of kitchen garbage was 90% (V/V) and the initial pH value of medium was 6, the inoculum was 10% (V/V) at 30 ℃ for 10 d with agitation speed at 180 r/min and aeration rate at 2.5 L/min in a 1L fermentator. Results showed that the S. cerevisiae As 2.516 biomass accumulation presented an S-shaped curve during fermentation, the production of microbial oil displayed a closed correlation with the bacteria biomass. The batch fermentation kinetic models were established (cell growth kinetic model, substrate depletion kinetic model, production formation kinetic model) based on Logistic equations, Luedeking-Piret equations and mass balance calculation. Cell growth kinetic model was dx/dt = 1.0241x(1 - x/13.05), substrate depletion kinetic model Was-ds/dt = 0.4787 dx-dt + 0.0348x + 0.1055 dp/dt, and production formation kinetic model was dp/dt = 02979 dx/dt+ 0.00406x , The experimental results fit the predictive values from these proposed models.The correlation coefficients R2 of the three equations were 0.9979, 0.9957, 0.9565, respectively, which indicated a good correlation between experimental values and models. Therefore, those models could be used to describe the process of cell growth, substrate consumption for production of microbial oils by S cerevisiae As2.516 during batch fermentation. The establishment of batch fermentation kinetic models could lay a foundation for theory and provide practical instruction for the application of production microbial oils.