乳酸乳球菌双组分系统调控有氧呼吸的研究

Preliminary study on the regulation of aerobic respiration by two-component system of Lactococcus lactis

摘要:

【背景】乳酸乳球菌作为食品行业的代表性菌株，如何通过双组分系统响应环境因子与代谢调控的分子机制研究，对发酵食品产业和益生菌制剂行业有着重要的意义。【目的】探究乳酸乳球菌双组分系统对有氧呼吸代谢调控的相关网络，为乳酸菌适应性代谢研究提供新思路。【方法】采用生物信息学方法，系统性地分析乳酸乳球菌双组分系统组氨酸激酶和反应调节因子的结构域组成及预测双组分系统功能，筛选出与有氧呼吸有潜在联系的双组分，并进一步通过基因转录表达和非靶向代谢组学验证。【结果】以乳酸乳球菌的代表菌株NZ9000为例构建相互作用蛋白网络，显示双组分系统与丙酮酸代谢网络关键连接点为丙酮酸铁氧还蛋白氧化还原酶(nifJ)。在不同的生长时期，Lactococcus lactis NZ9000双组分转录表达在延滞期变化显著。与厌氧培养相比，有氧培养和有氧呼吸培养的菌体双组分呈现下调趋势。双组分系统参与乳酸菌氧化应激和血红素胁迫过程。【结论】明确乳酸乳球菌参与有氧呼吸的双组分系统以及代谢通路，有助于提高发酵剂、益生菌剂的存活率和竞争力。

关键词:乳酸乳球菌;双组分系统;有氧呼吸;适应性机制

Abstract:

[Background] Lactococcus lactis is a representative strain in the food industry. The molecular mechanism of L. lactis responding to environmental factors and the metabolic regulation through the two-component system is of great importance to the fermented food and the probiotics industries. [Objective] This study aimed to explore the effect of two-component system of L. lactis on aerobic respiration metabolism, and was expected to supply a new direction for adaptive metabolism in lactic acid bacteria. [Methods] The domainof sensor histidine kinases and response regulatory factor as well as the function of the two-component system in L. lactis was systematically analyzed using bioinformatics methods. The correlations between two-component system and aerobic respiration were calculated and further verified by transcriptional expression and untargeted metabolomics. [Results] The protein-protein interaction network of the representative L. lactis strain NZ9000 showed that the key connection point between the two-component system and pyruvate metabolism in the network was pyruvate-ferredoxin oxidoreductase (nifJ). At different growth stages, the transcriptional expression of the two-componentsystem in L. lactis NZ9000 changed significantly in the lag period. Compared with the anaerobic culture, the transcriptional expression of the two-component system in L. lactis NZ9000 cultivated under aerobic culture and aerobic respiratory culture was down-regulated. The two-component system participated in oxidative stress and heme stress in lactic acid bacteria. [Conclusion] To identify the two-component system and metabolic pathway of Lactococcus lactis involved in aerobic respiration. It can improve the survival rate and competitiveness of starters and probiotics.

Key words:Lactococcus lactis;two-component system;aerobic respiration;adaptive mechanism