L-谷氨酸钠对酸胁迫下短乳杆菌NCL912蛋白表达的影响

Effect of Sodium L-Glutamate on Protein Expression ofγ-Aminobutyric Acid-Producing Lactobacillus brevis NCL912 under Acid Stress

从蛋白质组学水平,对高产γ-氨基丁酸短乳杆菌NCL912在酸胁迫应激过程中菌体蛋白质的变化,以及L-谷氨酸钠对酸胁迫下该菌差异蛋白的表达和功能的影响进行分析和比较。凝胶电泳和质谱分析结果表明,在酸胁迫条件下,未添加L-谷氨酸钠的培养基培养的短乳杆菌NCL912有25个差异表达蛋白,其中8个蛋白点得到了鉴定;而添加L-谷氨酸钠的培养基培养的该菌有26个差异表达蛋白,其中11个蛋白点得到了鉴定。对两组样品中鉴定的蛋白质功能进行分析比较,发现在酸胁迫条件下,无论是否添加底物氨基酸,该菌都会启动一些共同的应激过程来保护自身,如蛋白质的合成、糖代谢及应激蛋白表达量的变化等。而外源氨基酸的添加可能会诱导某些与细胞生物膜及信号转导有关的蛋白表达发生改变,从而有利于细胞能够在酸性环境中生存和生长。这表明酸胁迫应激过程是一个复杂的网络调控体系,不仅与外部氨基酸的添加有关,还涉及到菌体内部其他蛋白质的变化。

Lactobacillus brevis NCL912 is aγ-aminobutyric acid-producing strain isolated from fermented vegetables.In the present study,protein expression in Lb.brevis NCL912 was investigated at the proteomic level and the effect of sodium L-glutamate（L-MSG） on protein expression was also explored under acid stress by two-dimensional gel electrophoresis,mass spectroscopy and bioinformatics.Eleven spots of 26 differential expressed proteins from the culture with L-MSG and 8 spots of 25 proteins from the culture without L-MSG were identified.The results showed that Lb.brevis NCL912 might launch the common acid resistance systems such as protein synthesis,glycometabolism and stress proteins to protect the cells against acid stress,which was irrelevant to L-glutamate.Meanwhile,exogenous amino acids might change the expression of some of the proteins which were involved in cell membrane formation and signal transduction in media with L-glutamate,thus benefiting the survival and growth of the cells.Therefore,the acid resistance-responsive system is a very complex network system,which is related to not only exogenous amino acids,but also the expression of bacterial proteins.