添加脂类物质对米酒乳杆菌生境适应相关基因表达的影响

Effects of fat/ester addition on niche-specific genes expression of Lactobacillus sakei

为了了解米酒乳杆菌在脂类环境中的生存状况,为改进发酵剂和发酵产品提供理论基础,用定量PCR方法对米酒乳杆菌La22在橄榄油和三丁酸甘油培养基中生长时生境适应相关基因表达进行分析。结果显示,与对照相比,无论是在添加橄榄油还是添加三丁酸甘油的MRS培养基中,米酒乳杆菌中与精氨酸脱亚氨酶途径(ADI)途径相关的6个arc操纵子基因的表达量下调十分明显,且在橄榄油中arc操纵子基因的表达量均低于其在含三丁酸甘油培养基中的表达量;压力相关基因usp5在三丁酸甘油培养基中的表达量明显下调,usp2、usp4、lsa0169和lsa0170在2种培养基中的表达量均明显下调,lsa01079的表达量在三丁酸甘油培养基中明显上调,lsa0674和lsa0697在2种培养基中的表达量均明显上调;应激基因lsa1152_b在橄榄油和三丁酸甘油培养基中的表达量明显上调,而lsa1111、lsa1112、lsa0552和lsa0619基因的表达量在三丁酸甘油培养基中明显下调。结果表明米酒乳杆菌能适应脂类丰富的培养环境,但需进一步研究来证实米酒乳杆菌对各种脂类环境的适应性。

Lactobacillus sakei is a ubiquitous heterofermentative lactic acid bacterium that is frequently used as an industrial culture in vegetable,fish and meat fermentation.To investigate the adaptation of L.sakei in a fat/ester environment and to provide fundamental basis for improvement of starter culture and fermented product,real-time quantitative PCR（RT-q PCR） were employed to analyze the niche-specific genes expression related to the growth of L.sakei strain La22 when grown in olive oil or tributyrin supplemented MRS.Compared with CK,expression of six arc operon genes of L.sakei strain La22,which belong to the arginine deiminase（ADI） pathway,were down-regulated obviously and the expression of six arc operon genes in olive oil supplemented MRS was lower than that in tributyrin supplemented MRS.Expression of the stress response gene usp5 was down-regulated in MRS containing tributyrin,and genes usp2,usp4,lsa0169 and lsa0170 were under-expressed in olive oil or tributyrin supplemented MRS.lsa01079 gene was up-regulated in MRS containing tributyrin and genes lsa0674 and lsa0697 were over-expressed in olive oil or tributyrin supplemented MRS.Cold/heat shock gene lsa1152_b was over-expressed in MRS containing olive oil or tributyrin and genes lsa1111,lsa1112,lsa0552 and lsa0619 were under-expressed in MRS containing tributyrin.The results suggested that the L.sakei is adapted to the fat/ester abounding environment.Further studies will be focused on the adaptability of L.sakei to environment containing different fat/ester.