利用啤酒废酵母间歇发酵合成谷胱甘肽的研究

Study on the Batch Fermentation for the Production of Glutathione with Spent Brewer's Yeast

研究利用啤酒废酵母生产谷胱甘肽的目的是降低谷胱甘肽生产成本、提高啤酒废酵母附加值.研究考察了在2升通气搅拌罐中通气量、搅拌速度、初始葡萄糖浓度以及废酵母加入量对谷胱甘肽合成的影响.实验表明,好氧活化可以显著提高酵母细胞内的谷胱甘肽含量.由于啤酒废酵母的添加量较大,使得反应液中菌体浓度较高,发酵过程中保持较大的通气量和搅拌速率有利于提高细胞活性和促进谷胱甘肽的积累.通过实验确定了2L发酵罐中较佳的操作参数为搅拌速度500r@min-1,通气量6 L@L-1@min-1.过高的初始葡萄糖浓度对谷胱甘肽的合成有一定的抑制作用,比较合适的初始葡萄糖用量为加入的废酵母湿重的10%.废酵母加入量增大会导致胞内谷胱甘肽含量下降,但由于细胞干重的大幅度增加,在实验范围内,最终单位反应器体积的谷胱甘肽产量则随废酵母加入量增大而增大.实验表明,废酵母加入量在湿酵母为100～300g@L-1之间是合适的.

The purpose of choosing spent brewer抯 yeast to produce glutathione (GSH) is to reduce the producing cost of GSH and to enhance the value of spent brewer抯 yeast. Aerobic activation of the spent brewer抯 yeast is needed to improve glutathione content in yeast cells. The experiments were carried out in a 2 L aerated stirred-tank. The effects of different fermentation parameters such as aeration rate, agitation speed, initial glucose concentration and addition amount of spent brewer抯 yeast on GSH production were investigated. The origin intracellular glutathione content in spent brewer抯 yeast was quite low, but it increased obviously during the aerobic activation. Due to the high initial cell concentration used, the enhancement of air flux and the stirring rate benefits both of cell growth and GSH accumulation. The optimal fermentation parameters were found to be 500rmin-1 of agitation speed and 6L(L-mediummin)-1 of aeration rate. It was also found that the glutathione production was inhibited by high concentration of glucose, so the initial glucose concentration should be limited. An initial concentration of glucose as much as 10% of the addition amount of wet yeast is appropriate to satisfy the need of aerobic activation. The intracellular content of glutathione decreases when the addition of spent brewer抯 yeast is increased from 100gL-1to 300gL-1, but the total volumetric yield of glutathione increases instead, because the decline of intracellular content is less than the enhancement of biomass. Final decision of the yeast addition amount should be made according to the local price of spent brewer抯 yeast.