烟酸促进短乳杆菌合成γ-氨基丁酸的机制

Nicotinic Acid Promotesγ-aminobutyric Acid Biosynthesis in Lactobacillus brevis

短乳杆菌发酵时添加0.15%的烟酸可显著提高γ-氨基丁酸(GABA)的产量,为阐明烟酸的作用机制,本研究采用液相色谱-质谱联用(LC-MS)的方法探究短乳杆菌添加(实验组)和不添加烟酸(对照组)发酵时的差异代谢物,并采用碘化丙啶(PI)单染色法分析了细胞膜的完整性。结果表明实验组和对照组之间显著性差异代谢物有33个,实验组中不饱和脂肪酸的含量,谷氨酸、脯氨酸、天冬氨酸、丝氨酸、组氨酸和鸟氨酸含量显著提高,烟酸核苷酸、2-磷酸甘油酸、腺苷一磷酸和酪胺的含量显著降低。碘化丙啶单染色实验表明实验组中具有红色荧光的短乳杆菌细胞显著多于对照组细胞。因此,烟酸的添加对短乳杆菌的生理代谢具有全局性的影响,其对GABA合成的促进作用可能与增加短乳杆菌细胞膜通透性进而导致的底物和产物更加容易进出细胞有关。

Adding 0.15%nicotinic acid to medium significantly increased theγ-aminobutyric acid(GABA)production of Lactobacillus brevis.In order to clarify the role of nicotinic acid,L.brevis was inoculated in the medium with(experimental group)and without nicotinic acid(control group)for fermentation.The differential metabolites were studied by liquid chromatography-mass spectrometry(LC-MS),and the integrity of cell membrane was analyzed using propidium iodide(PI)single staining method.The results showed that 33 metabolites were significantly different between the experimental group and the control group.The unsaturated fatty acids and some amino acids including glutamate,proline,aspartate,serine,histidine,and ornithine,significantly increased in the experimental group,whereas nicotinic acid nucleotide,2-phosphoglycerate,adenosine monophosphate and tyramine significantly decreased.PI single staining experiments demonstrated that the cells with red fluorescence in the experimental group were significantly more than those in the control group.Therefore,the addition of nicotinic acid has a broad impact on the physiological metabolism of L.brevis,and its promoting effect on GABA biosynthesis may be related to increasing the permeability of the cell membrane of L.brevis,resulting in easier substrates entry into the cells and easier products discharge from the cells.