乳酸对酵母凋亡及某些相关基因表达的影响

采用终浓度为200、250、300 mmol.L-1的乳酸作用酵母细胞200 min,同时,采用终浓度为250mmol.L-1的乳酸分别作用酵母细胞120、200、260 min后,通过DAPI染色、PI染色和TUNEL染色法检测酵母细胞的凋亡。结果表明,随着乳酸终浓度的增加,酵母的死亡率随之增加。死亡的细胞出现DNA断裂和染色质凝聚现象,但没有显示膜损伤,所以乳酸引起的酵母细胞死亡是以凋亡的形式进行。200 mmol.L-1乳酸处理酵母200 min,可引起约不到30%的凋亡,当终浓度增加到300 mmol.L-1时,凋亡率可达80%以上,乳酸引起的死亡率和凋亡率具有剂量依赖性,但无时间依赖性。RT-PCR检测结果表明,随着凋亡程度的增加,Fis1、Bir1、SOD1、SOD2基因的表达随之降低。

Effect of lactic acid on yeast apoptosis and expression of apoptosisrelated gene

Lactic acid is a product of yeast fermentation and can impact on the production capacity of yeast.Mechanism research of yeast apoptosis influenced by lactic acid will be helpful for improving the production capacity of yeast.In this study,the final concentration of lactic acid impacting on yeast were 200,250,300 mmol.L-1 for 200 min,and 250 mmol.L-1 for 120,200,260 min.Then yeast cells were collected for the detections of DAPI staining,PI staining and TUNEL staining,separately.The results showed that with the increasing of final concentration of lactic acid,the mortality rate of yeast increased.The cells appeared DNA breaks and chromatin condensation,but no membrane damage.It indicated that mortality of yeast cell was induced by lactic acid through apoptosis.When the final concentration of lactic acid was 200 mmol.L-1 for 200 min,the apoptosis rate was less than 30%,while 300 mmol.L-1 for 200 min it reached above 80%.It showed that dose-dependent,but no time-dependent.Moreover,the results of RT-PCR showed mRNA levels of Fis1,Bir1,SOD1,and SOD2 decreased with increasing apoptosis.