乳酸菌生物吸附转化展青霉素与缓解展青霉素毒性的机制分析

Patulin is an unsaturated heterocyclic lactone mycotoxin produced by certain filamentous fungi with multiple-organ toxicities and has become an important risk factor for food and feedstuff safeties. We have found that some certain lactic acid bacteria strains have the ability to adsorb and transform patulin and alleviate patulin toxicity in Balb/c mice model, but the mechanism of such protective effects is still unknown. Based on our preliminary research, this research is proposed to investigate the mechanisms underlying the inhibition of penecillia mycelia growth and patulin formation by lactic acid bacteria. The in vitro biosorption model is used to study the specific modes of bioabsorption and biotranformation of patulin by lactic acid bacteria, and to elucidate the detailed mechanisms of such bioabsorption and biotranformation on cellular and molecular levels. The cultured cell model is used to investigate the patulin-induced damage of cultured cells and protective effects by lactic acid bacteria against patulin toxicities. We use the animal model to study the alleviation effects of lactic acid bacteria administration against patulin-induced toxicities in the biochemical, physiological, and metabolic indicators. At the same time, the protective mechanism is also probed in patulin-exposed animal models with transcriptomic and metabolomic analysis tools. We also use metagenomics tools to study the impact of patulin exposure and the beneficial intervention by lactic acid bacteria on the gastrointestinal microbiome. The results will give us some new insights in the patulin biocontrol and safety assurance by lactic acid bacteria and provide theoretical guidance for the related research and application.

展青霉素是某些真菌产生的具多靶器官毒性的不饱和杂环内酯型毒素，已成为影响食品和饲料安全的重要风险因素。申请人研究发现某些乳酸菌能吸附并转化展青霉素并在Balb/c小鼠模型中表现出缓解展青霉素毒性的效应，然而相关的机制尚未见报道。基于此申请人拟研究乳酸菌抑制青霉生长和毒素合成的作用机制；利用体外模型研究其吸附规律，在细胞和分子水平上阐明植物乳杆菌吸附和降解展青霉素的作用模式；通过细胞模型研究展青霉素对培养模型细胞的损伤及乳酸菌对展青霉素导致损伤的保护作用；通过动物模型研究植物乳杆菌摄入在生理生化与代谢标志物指标上对展青霉素毒性的缓解作用，利用组学分析技术揭示乳酸菌缓解展青霉素毒性的作用机制；利用宏基因组技术研究展青霉素暴露对肠道微生态的影响。研究结果将在利用乳酸菌对展青霉素进行生物控制和安全保证方面形成干预展青霉素的新认识，为相关研究与应用提供理论依据。

环境中存在着展青霉素、黄曲霉毒素、脱氧雪腐镰刀菌烯醇等多种具有显著毒性作用的真菌毒素。环境和食物中的真菌毒素暴露已经成为影响食品安全和人群健康的重要风险因素。我们前期研究初步发现乳酸菌可生物减除展青霉素毒害，但我们对乳酸菌针对展青霉素如何进行体外降解、体内减毒的作用方式和机制不甚了解。基于该科学问题，我们通过乳酸菌细胞-展青霉素体外相互作用水平、肠道细胞和小鼠动物模型解析了乳酸菌对展青霉素的合成、降解和缓解展青霉素毒性的作用机制。研究发现乳酸菌发酵上清液对扩展青霉的最低抑制浓度为15%，其中多种有机酸可显著降低扩展青霉中展青霉素合成基因的表达，进而有效抑制展青霉素的合成。此外，经过乳酸菌的体外发酵，43.28%的展青霉素被降解。并且基于转录组学技术，结果显示展青霉素胁迫下乳酸菌胞内醛酮还原酶调控基因的表达量发生及其显著的提升，进一步将该醛酮还原酶调控基因通过异源表达手段，纯化得到醛酮还原酶（LpAKR），并验证其可降解展青霉素的功能。在展青霉素暴露细胞模型中，乳酸菌干预能恢复细胞活力，清除毒素暴露产生的ROS，调节肠细胞紧密连接蛋白的表达与合成，对肠道屏障发挥保护作用。此外，膳食补充乳酸菌能显著缓解展青霉素暴露导致的小鼠组织损伤，调节免疫应激，同时对小鼠肠道微生态的紊乱具有显著的保护作用。综上所述，以乳酸菌为基础的膳食干预政策，可实现抑制毒素合成、体外毒素降解、体内展青霉素毒性的缓解，并为相关研究的与应用开发提供了必要的理论依据和技术指导。