Research on Condition of Co-Culture Glutathione by Yeast and Lactobacillus

Optimized co-culture conditions were obtained by Plackett-Burman design and orthogonal design with the co-culture of Saccharomyces cerevisiae and Lactobacillus casei based on single factor experiment.It was to promote the yield of glutathione produced by Saccharomyces cerevisiae.Alloxan method was used to measure the yield of glutathione.Single factor experiment,Plackett-Burman design and orthogonal design were applied to optimize the co-culture condition.First,the single factor experiment of co-culture was to select the factors,lactose concentration,initial pH value of fermentation media,co-culture temperature,co-culture rotation speed,inoculum amount of Lactobacillus,inoculum time of Lactobacillus and fermentation time,relevant to the yield of glutathione.On the basis of the results of single factor experiment,the two levels of the seven factors for Plackett-Burman design was identified.Minitab 16 is a statistical software which was applied to conduct the Plackett-Burman design of the seven factors.Three significant impact factors were screened based on the value of P.And positive or negative effects of all factors were determined.The orthogonal experiment of the three factors was carried by SPSS 19 to achieve the optimized fermentation condition.The optimized fermentation conditions were obtained according to the best mean value corresponding to every factor of glutathione yield.The optimized fermentation conditions were as follows:lactose concentration 40 g/L,initial pH value of fermentation media 6.4,co-culture temperature 36 ℃,co-culture rotation speed 200 r/min,inoculum amount of Lactobacillus 8%,inoculum time of Lactobacillus 8 h and fermentation time 24 h.The yield of glutathione was 1.93mmol/L and increased by 35.14% under the optimized fermentation condition compared with the previous condition.It was increased by 33.35% under the same fermentation condition compared with monoculture.It was feasible to produce glutathione by co-culture of Saccharomyces cerevisiae and Lactobacillus casei.Single factor experiment,Plackett-Burman design and orthogonal design were efficient to optimize the fermentation conditions and to raise the glutathione yield.