餐厨垃圾水解液发酵产油脂特性及动力学研究

Characteristics and Kinetics of Oil Production from Kitchen Waste Hydrolysate Fermentation

为探究餐厨垃圾水解液发酵产油脂的动力学特征和影响因素,以Saccharomyces cerevisiae As2.516(S.cerevisiae As2.516)为供试菌株,在初始餐厨垃圾水解液加入量为90%、搅拌速率为180 r/min、通气量为2.5 L/min、发酵周期为10 d的条件下,进行1 L发酵罐发酵实验。实验结果表明,S.cerevisiae As2.516的最优初始培养条件如下:pH值为6、温度为30℃、生物接种量为10%;在此实验条件下,发酵第7天油脂产量最高达4.6 g/L,此时生物量为13 g/L,油脂产率为36.1%;发酵产生的脂肪酸主要由C16和C18脂肪酸组成。餐厨垃圾水解液中的无机盐钠(Na^(+))、钾(K^(+))、铁(Fe^(3+))、镁(Mg^(2+))、锰(Mn^(2+))含量丰富,除需添加微量硫酸铜(CuSO_(4)·5H_(2)O,0.1 mg/L)外,无需额外添加其他无机盐。同时基于Logistic方程和Luedeking-Piret等方程建立了S.cerevisiae As2.516菌体生长、产物生成、底物还原糖消耗3个发酵动力学模型,较好地描述了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过程。

To investigate the kinetic characteristics and influencing factors of oil production from kitchen waste hydrolysate fermentation, a fermentation experiment was carried out in a 1 L fermenter, in which Saccharomyces cerevisiae As2.516(S. cerevisiae As2.516) was used as a test strain the dosage of initial kitchen waste hydrolysate was 90%, agitation speed was 180 r/min, aeration rate was 2.5 L/min and fermentation cycle was 10 days. The initial optimal culture conditions for S. cerevisiae As2.516 were as follows: pH of 6, temperature of 30 ℃ and inoculation percentage of 10%. Based on the optimum culture condition, the highest oil yield was 4.6 g/L on the 7 th day of fermentation, the biomass was 13 g/L and the oil yield rate was 36.1%. Fatty acids produced by fermentation were mainly composed of C16 and C18 fatty acids. Contents of sodium(Na^(+)), potassium(K^(+)), iron(Fe^(3+)), magnesium(Mg^(2+)) and manganese(Mn^(2+)) in the kitchen waste hydrolysate were abundant, and there was no need to add other inorganic salts except for adding trace copper sulfate(CuSO_(4)·5 H_(2)O, 0.1 mg/L). In addition, three fermentation kinetics models of S. cerevisiae As2.516 growth, production formation and substrate(reducing sugar) depletion were established based on Logistic and Luedeking-Piret equations, and the process of cell growth, oil synthesis and substrate(reducing sugar) consumption could be well described by these models.