中文摘要：

米酒乳杆菌是常见的异型发酵乳酸菌,常常用于肉类工业发酵剂。为了了解其在肉类环境中对氮源的代谢机制,用定量PCR对米酒乳杆菌La22在添加肌浆蛋白和肌原纤维蛋白的培养基中生长时蛋白质代谢相关基因的表达量进行分析。结果显示,La22在添加猪肉蛋白的2种培养基中生长时,有6个与天冬氨酸和谷氨酸代谢相关的基因表达量发生了明显变化,在S-CDM培养基中生长时,基因asnA2明显上调,基因pyrB、purA和glnA明显下调;在M-CDM培养基中生长时,pyrB、asnA1和purF明显上调,而purA和glnA明显下调;胞外蛋白酶仅有clpL基因在2种培养基中均表现为明显上调。在S-CDM培养基中hslV基因明显下调,而在M-CDM中,基因prtM、hslU和clpE均表现为明显下调。在添加猪肉蛋白的CDM培养基中生长时,编码Opp系统的5个基因中,只有oppB和oppC表达量明显上调,而dtpT基因则明显下调;基因puopT在M-CDM培养基中明显上调,而在S-CDM中上调不明显。有7种编码米酒乳杆菌肽酶的基因在2种猪肉蛋白培养基中表达量上调。结果表明米酒乳杆菌能通过蛋白质代谢基因表达调节来适应含猪肉蛋白的培养环境。

英文摘要：

Lactobacillus sakei is a ubiquitous heterofermentative lactic acid bacteria that is frequently used as an meat industrial culture.To investigate the nitrogen metabolism in a meat protein environment,q RT-PCR were used to analyze the nitrogen metabolism genes expression related to growth of L.sakei strain La22 when grown in myofibrillar and sarcoplasmic supplemented CDM.The results showed that in two meat protein medium,six genes related to aspartate and glutamate metabolism were changed.Among these genes,expression of the genes asn A2 was up-expression and pyr B,pur A and gln A were down-expression obviously in sarcoplasmic containing CDM and genes pyr B,asn A1 and pur F were overexpression and pur A and gln A were underexpression obviously in myofibrillar containing CDM.Only gene clp L,which related to protease synthesis was up-expression in two meat protein medium.Gene hsl V down-expressed in sarcoplasmic supplemented CDM and genes prt M,hsl U and clp E were downexpression in myofibrillar containing CDM.Two genes,opp B and opp C,were up-expression in five genes encoding Opp system in two meat protein medium,and dtp T down-expressed obviously.Gene poup T was up-expression only in myofibrillar containing CDM.Seven genes encoding peptidase of L.sakei were overexpression in two meat protein medium.The results suggested that the L.sakei is adapted to the meat protein environment by modulating nitrogen metabolism genes expression.