Zhang Min, Yao Mengke, Lai Tiantian, Zhao Hua, Wang Yihui, Yang Zhennai
Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, Beijing Technology and Business University, Beijing 100048, China.
Foods. 2021 Jun 30;10(7):1514. doi: 10.3390/foods10071514.
To understand the mechanism of tolerance of lactic acid bacteria (LAB) during cold storage of fermented milk, 31 LAB strains were isolated from traditional fermented products, and NMGL2 was identified with good tolerance to both cold and acid stresses. Data-independent acquisition proteomics method was employed to analyze the response of NMGL2 to the combinational cold and acid stresses during storage of the fermented milk made with the strain at 4 °C for 21 days. Among the differentially expressed proteins identified, 20 low temperature-resistant proteins and 10 acid-resistant proteins were found. Protein interaction analysis showed that the low temperature-resistant proteins associated with acid-resistant proteins were Hsp1, Hsp2, Hsp3, CspC, MurA1, MurC, MurD, MurE1, and MurI, while the acid-resistant proteins associated with low temperature-resistant proteins were DnaA, DnaK, GrpE, GroEL, and RbfA. The overall metabolic pathways of NMGL2 in response to the stresses were determined including increased cell wall component biosynthesis, extracellular production of abundant glycolipids and glycoproteins, increased expression of FF-ATPase, activation of glutamate deacidification system, enhanced expression of proteins and chaperones associated with cell repairing caused by the acidic and cold environment into the correct proteins. The present study for the first time provides further understanding of the proteomic pattern and metabolic changes of in response to combinational cold and acid stresses in fermented milk, which facilitates potential application of in fermented foods with enhanced survivability.
为了解乳酸菌（LAB）在发酵乳冷藏过程中的耐受机制，从传统发酵产品中分离出31株LAB菌株，并鉴定出对冷应激和酸应激均具有良好耐受性的NMGL2。采用数据非依赖采集蛋白质组学方法，分析了NMGL2在4℃下用该菌株制作的发酵乳储存21天期间对冷酸复合应激的反应。在鉴定出的差异表达蛋白中，发现了20种耐低温蛋白和10种耐酸蛋白。蛋白质相互作用分析表明，与耐酸蛋白相关的耐低温蛋白有Hsp1、Hsp2、Hsp3、CspC、MurA1、MurC、MurD、MurE1和MurI，而与耐低温蛋白相关的耐酸蛋白有DnaA、DnaK、GrpE、GroEL和RbfA。确定了NMGL2响应应激的整体代谢途径，包括细胞壁成分生物合成增加、丰富的糖脂和糖蛋白的细胞外产生、FF - ATP酶表达增加、谷氨酸去酸化系统激活、与细胞修复相关的蛋白质和伴侣蛋白表达增强，这些蛋白质由酸性和寒冷环境导致正确折叠。本研究首次进一步了解了NMGL2在发酵乳中对冷酸复合应激的蛋白质组模式和代谢变化，这有助于NMGL2在发酵食品中更具生存能力的潜在应用。
