Glutamate Dehydrogenase Activity Can Be Transmitted Naturally to Lactococcus lactis Strains To Stimulate Amino Acid Conversion to Aroma Compounds
Glutamate Dehydrogenase Activity Can Be Transmitted Naturally to Lactococcus lactis Strains To Stimulate Amino Acid Conversion to Aroma Compounds
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DOI：
10.1128/aem.72.2.1402-1409.2006
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发表时间：
2006-02
影响因子：
4.4
通讯作者：
Catherine Tanous;Émilie Chambellon;D. le Bars;G. Delespaul;M. Yvon
中科院分区：
文献类型：
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作者：
Catherine Tanous;Émilie Chambellon;D. le Bars;G. Delespaul;M. Yvon
乳酸乳球菌将氨基酸转化为芳香化合物受到α-酮戊二酸产量低的限制，而α-酮戊二酸是转化的第一步所必需的。最近，在L.乳酸菌菌株分离的植物源，和基因负责的活动，在L。乳酸菌NCDO 1867进行了鉴定和表征。该基因位于一个70 kb的质粒上，也编码镉抗性。本研究中，gdh基因失活和过表达证实了GDH活性直接影响L。乳酸在氨基酸催化剂上在pH 5.5的反应介质中，奶酪的pH。利用镉抗性作为选择标记，将携带gdh的质粒自然传递到另一株L.乳酸菌菌株通过交配程序。转移赋予宿主菌株GDH活性和在反应介质中存在谷氨酸的情况下分解代谢氨基酸的能力。然而，该质粒在还含有蛋白酶乳糖质粒pLP 712的菌株中似乎不稳定，表明这两种质粒之间不相容。
ABSTRACT Amino acid conversion to aroma compounds by Lactococcus lactis is limited by the low production of α-ketoglutarate that is necessary for the first step of conversion. Recently, glutamate dehydrogenase (GDH) activity that catalyzes the reversible glutamate deamination to α-ketoglutarate was detected in L. lactis strains isolated from a vegetal source, and the gene responsible for the activity in L. lactis NCDO1867 was identified and characterized. The gene is located on a 70-kb plasmid also encoding cadmium resistance. In this study, gdh gene inactivation and overexpression confirmed the direct impact of GDH activity of L. lactis on amino acid catabolism in a reaction medium at pH 5.5, the pH of cheese. By using cadmium resistance as a selectable marker, the plasmid carrying gdh was naturally transmitted to another L. lactis strain by a mating procedure. The transfer conferred to the host strain GDH activity and the ability to catabolize amino acids in the presence of glutamate in the reaction medium. However, the plasmid appeared unstable in a strain also containing the protease lactose plasmid pLP712, indicating an incompatibility between these two plasmids.