Probiotic mechanisms of Lactobacillus in metal detoxification

乳酸菌在金属解毒中的益生机制

• 批准号: RGPIN-2014-05188
• 负责人: Reid, Gregor
• 金额: $ 2.48万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=663150
• 关键词: Probiotic; mechanisms; Lactobacillus; metal; detoxification

Hypothesis. *We hypothesize that members of bacterial genus, Lactobacillus, have developed the ability to acquire specific genetic elements in order to sequester heavy metals to which they are exposed in the environment. * *Background and Objectives.*Lactobacilli are Gram positive facultative anaerobic or microaerophilic rod-shaped bacteria notable for their use in the production of a range of foods, including yogurt, cheese, sauerkraut and pickles as well as silage for animal feed. Of the 180 or so species of Lactobacillus, the L. casei and L. rhamnosus species are of particular interest as they are ubiquitous in fermented foods and a number of strains have proved effective as probiotics. We are intrigued by their adaptability to grow in various foods and survive in conditions within the body and we wondered if they cope with the presence of heavy metals known to contaminate the food chain and the intestine. We have discovered that sequestration and detoxification of mercury does indeed occur in lactobacilli, and appears to be associated with a characterized three-gene reverse trans-sulfuration pathway involved in cysteine metabolism in L. casei DN114-226, We also discovered that resistance to mercury can be induced in L. rhamnosus DN 116-060 after incubation in sub-inhibitory mercury concentrations; the lactobacilli have both a decreased lag growth period and higher minimum inhibitory concentrations when grown in Hg2+. The screening uncovered only this strain, and one other related L. rhamnosus strain possessing a rare horizontally acquired element encoding a minimal mercury resistance operon imparting inducible resistance to mercury by volatilizing the metal. **Research aim and objectives *The aim of our program is to understand how Lactobacillus acts as a heavy metal detoxifying agent. The five year program designed for two graduate students each year has three objectives:*1. Verify the genetic elements that play a role in active and passive mercury resistance and detoxication. *2. Determine how exposure to mercury affects L. rhamnosus DN116-060 functionality *3. Test the concept in a murine model. **Using Lactobacillus rhamnosus DN116-060, L. casei DN114-226, and probiotic L. rhamnosus GR-1 as a control and gene recipient, all due to their ability to propagate in food and characteristics of interest, we will use knock-outs and gene insertion to optimize the ability of lactobacilli to bind to mercury. We will perform studies that provide insight into the mechanisms of these actions, including altering genetics and surface properties of lactobacilli to modify the active passive sequestration of mercury, respectively, and doing transcriptomic analysis to understand functionality. A cell culture and mouse model will be used for in vivo experiments. **Significance and Future Studies: *Heavy metal poisoning is common in certain parts of the world, and here in Canada exposure levels vary and remain a cause for concern. If beneficial bacteria can be utilized to reduce adsorption of mercury through foods, this could have an impact on morbidity and mortality.

假设。 *我们假设细菌属的成员乳酸杆菌已经发展出获得特定遗传元素的能力，以隔离它们在环境中暴露的重金属。 * *背景和目标。 *乳杆菌是革兰氏阳性疗法厌氧或微粒细胞形棒状细菌，以其在生产一系列食物中使用，包括酸奶，奶酪，奶酪，酸菜，酸菜和泡菜，以及灰烬以及动物饲料的青贮饲料。在180种左右的乳杆菌中，酪蛋白乳杆菌和鼠李乳杆菌物种特别有趣，因为它们在发酵食品中无处不在，并且已证明有许多菌株作为益生菌有效。我们对它们在各种食物中生长并在体内的疾病中生存的适应性很感兴趣，我们想知道它们是否应对已知的重金属存在会污染食物链和肠子的存在。我们已经发现，在乳酸杆菌中确实确实发生了汞的静止和排毒，并且似乎与casei dn114-226中半胱氨酸代谢相关的特征性的三基因反式反式硫化途径有关，我们还发现，在L. rhamnosus dn 116-60 in Incation中，我们还可以诱导汞的抵抗力。在Hg2+中生长时，乳酸杆菌的滞后生长周期降低，最小抑制浓度较高。筛选仅发现了该菌株，另一种相关的鼠李乳杆菌菌株具有罕见的水平收集元件，编码了最小的汞电阻操纵子，从而通过挥发金属来赋予对汞的诱导耐药性。 **研究目的和目标 *我们计划的目的是了解乳杆菌如何充当重金属排毒剂。每年为两名研究生设计的五年计划都有三个目标：*1。验证在主动和被动汞耐药性和解毒中发挥作用的遗传因素。 *2。确定暴露于汞如何影响鼠李乳杆菌DN116-060功能 *3。在鼠模型中测试概念。 **使用Ramnosus dn116-060，L。caseiDN114-226，益生菌L. rhamnosus gr-1作为对照和基因受体，所有这些都是由于它们在感兴趣的食物和感兴趣的食物中传播的能力，我们将使用敲除和基因插入能力，以优化lactobacilli的能力。我们将进行研究，以深入了解这些作用的机制，包括改变乳糖杆菌的遗传学和表面特性，分别修改汞的主动被动隔离以及进行转录组分析以了解功能。细胞培养和小鼠模型将用于体内实验。 **意义和未来的研究： *重金属中毒在世界某些地方很常见，在加拿大的暴露水平也有所不同，并且仍然是引起人们关注的原因。如果可以利用有益细菌通过食物来减少汞的吸附，这可能会对发病率和死亡率产生影响。