干酪乳杆菌发酵废弃烟梗制备L-乳酸操作参数的优化

Optimization of Operational Parameters for Preparation of L-lactic Acid by Fermentation of Waste Tobacco Stems with Lactobacillus casei

采用单因子试验研究了6个操作参数(发酵方式、发酵时间、装载量、接种量、发酵温度及初始p H)对干酪乳杆菌(Lactobacillus casei)XJL发酵废弃烟梗制备L-乳酸的影响。根据单因素试验结果,选取接种量、装载量、初始p H及发酵温度进行四因素三水平正交试验。结果表明:1初始p H、接种量和装载量对L-乳酸的产率影响显著。2最优操作参数组合为初始p H 7.0、装载量120/250m L(250 m L的锥形瓶装载120 m L的废弃烟梗提取液)、接种量(种子液的移入体积与接种后培养液体积的比例)7.5%、37℃静置培养48 h;此条件下,废弃烟梗发酵产L-乳酸可达157.50 g/kg。

Monofactorial experiments were performed including fermentation means, fermentation duration, to study the effects of six operational parameters, loading capacity, inoculum size, temperature and initial pH, on the preparation of L-lactic acid by the fermentation of waste tobacco stems with Lactobaeillus easei XJL. According to the results of monofactorial experiments, four factors （inoculum size, loading capacity, initial pH and temperature） were selected and orthogonally tested at three levels. The results showed that： 1） Initial pH, inoculum size and loading capacity significantly affected the yield of L-lactic acid. 2） The optimum operational parameters were initial pH 7.0, loading capacity 120/250 mL （120 mL tobacco stem extraction loaded in a conical flask of 250 mL）, inoculum size 7.5% （the volume ratio of transferred inoculant solution to total culture solution after inoculation）, static culture for 48 hours at 37 ℃; under the above conditions, the maximum yield of L-lactic acid reached 157.50 g/kg.