益生菌对食品中有害重金属的生物减除机制

The contamination of heavy metals including lead (Pb) and cadmium (Cd) has become an important threat to food safety and human health. Our preliminary work showed that probiotics have the ability to remove heavy metals in food, as well as to alleviate Pb and Cd induced oxidative stress in animals. The objective of this study is to further understand the biological removal mechanism of probiotics including Lactobacillus plantarum CCFM8661 and CCFM8610. Firstly, the biological response of probiotics during the heavy metal exposure is investigated with element speciation, metabolomic and comparative genomic analysis. Additionally, the protein molecular mechanism of biological removal is evaluated by proteomic analysis, molecular biological confirmation and immobilized metal affinity chromatography methods. Moreover, cell and animal models are established and the effects of probiotics on the inhibition of heavy metal absorption in the gut are investigated with omics-based analysis such as transcriptomic and metagenomic methods, in order to demonstrate the biological removal mechanisms of probiotics in vivo.

铅、镉等重金属已成为危害食品安全和人体健康的重要污染物。前期研究表明益生菌具有直接减除食品中重金属的潜力，同时也可缓解铅、镉暴露对机体造成的氧化应激和损伤。为深入理解益生菌生物减除重金属的分子机制，本课题以具有相关优良性状的植物乳杆菌CCFM8661及CCFM8610为研究对象，首先通过元素形态生化分析、代谢组学及比较基因组学手段研究阐明菌株在重金属暴露过程中生物响应机制；并利用蛋白质组学分析、分子生物学验证及固定金属离子亲和色谱手段研究菌株生物减除重金属的蛋白质分子机制；同时利用细胞和动物模型及转录组、宏基因组等组学手段，进一步研究菌株在肠道中对铅、镉吸收的抑制作用，以解析益生菌在宿主体内生物减除重金属的生理机制。

本项目对益生菌生物减除重金属铅、镉等的作用机制进行了深入探究，较好地完成了既定的研究计划。首先解析了益生菌耐受重金属胁迫的相关分子机制，通过蛋白组学以及代谢组学分析发现特定植物乳杆菌的高耐受能力主要与其高胞内渗透保护物质浓度、可诱导形成胞外聚合物、稳定的核酸代谢、专一性的能量节省生存模式以及致密的膜结构有关。进一步阐明了益生菌高效吸附重金属的蛋白质分子机制，证明特定菌株的吸附能力主要与表面蛋白有关，确定了3个镉吸附的关键蛋白，分别是胞外蛋白Lp19_0886、胞外蛋白AVR82_10195、氨基酸ABC转运蛋白oppA5。探究了不同食源性重金属的毒理学特性，发现不同食源性重金属毒性主要与其在肠道环境中解离重金属离子能力有关，且益生菌对不同食源性重金属毒性均有一定的缓解作用。进而通过体内功能验证模型探究了益生菌缓解重金属生物毒性的主要机制，利用宏基因组学、代谢组学、蛋白组学和金属组学等手段，发现益生菌可通过修复肠道屏障、缓解氧化应激、维护元素平衡、保护肠道微生物群落稳态以及促进重金属肝肠循环排出等机制缓解重金属毒性。最后开发了具有缓解重金属毒性潜力的膳食策略，发现低聚半乳糖、功能性肠道微生物和益生菌复配微生态制剂对铅生物毒性均有很好的缓解作用。本项目的开展为益生菌的功能开发提供了新的着眼点，并为食源性重金属暴露的生物减除提供新的膳食干预思路。