香辛料中赭曲霉毒素A累积规律及暴露评估

Mycotoxins contamination of food is a global problem, Ochratoxin A (OTA) is one of common toxins of Penicillium and Aspergillus species, which is easy to contamination during storage, may harm to human health. Spices are daily food for our residents, which has not research on the OTA produced fungi, accumulation rule and risk assessment of OTA in spices. Practical experience based on three years of China's major food mycotoxins contamination and evaluation project topics, this research intends to set OTA toxin as research objectives, set spices as the object of food matrix, establish the molecular biology methods (18S rDNA/ITS sequence analysis) to study the OTA produced fungal condition during the spice food storage, using Neighbor-Joining build phylogenetic tree, combined with morphological and biochemical characterization to study distribution and diversity of OTA produced fungi in spices. By means of the predictive microbiology to study the environmental conditions (temperature, water activity and pesticides, etc.) and environmental factor in the regulation of fungal toxin accumulation mechanism, and ultimately to clarify the environment aspects in the foundation of our spice storage that to guide the storage scientificly. In the end, through the point evaluation and the combination of the Monte Carlo model of probability assessment technical to assess the potential health risks on the spice OTA exposure levels to bring the people's health in China, this research will help the government to take effective regulatory means to solve the food safety issues in China scientifically, it will give an important theoretical and practical reference. Also, the study will be to understand and master the rule of OTA accumulation in spices and provides important basic data for pollution control.

真菌毒素污染食品是一个全球性问题，赭曲霉毒素A（OTA）是曲霉和青霉属真菌产生的常见毒素之一，危及人体健康。香辛料为我国居民每日摄入食品，当前还未针对香辛料中产OTA霉菌、累积规律及风险模型进行系统研究。本课题拟以OTA 毒素为研究目标，以香辛料为基质，以分子生物学手段（18S rDNA/ITS 序列分析）鉴定香辛料中产OTA 霉菌，采用Neighbor-Joining 法构建系统发育进化树并结合形态学、生化特征鉴定对产OTA 霉菌分布和多样性进行研究；通过预测微生物学“逆向”手段研究产OTA霉菌的环境因子调控真菌产毒累积动态规律，阐明香辛料中OTA 累积的环境基础；建立基于我国人口学特点的点评估和生命年蒙特卡洛等概率评估模型对OTA 暴露水平进行健康风险评估，阐明我国不同人群OTA摄入风险大小。该研究将对掌握我国香辛料食品中霉菌分布、OTA累积规律及污染控制提供十分重要的数据与依据。

赭曲霉毒素A（OTA）是曲霉和青霉属真菌产生的常见毒素之一，危及人体健康。通过构建样本容量函数，在满足置信度、抽样精度及变异性的情况下确定了香辛料样本最小抽样数量，通过分离纯化与形态学、ITS分子生物学等鉴定共分离得到26株霉菌（其中曲霉属为13株，青霉属为6株），样本中霉菌的总体污染率为80.7%，黄曲霉毒素（总量）污染率为3.3%，赭曲霉毒素污染率为8.7%，真菌毒素的总体污染率为11.3%。通过预测微生物学手段对所分离的产毒霉菌构建了香辛料基质中霉菌生长与产毒规律的预测模型，温度为28 °C、Aw为0.97、pH值为4.5时，辣椒粉中黄曲霉菌的生长速率和产毒量均达到最大；而对于产毒赭曲霉菌其在香辛料基质的实验室条件下并不能高含量累积毒素，其产毒调控机制需进一步研究。根据A. ochraceus OTA生物合成的关键基因（聚酮化合物合成酶基因PKS）的保守序列设计了特异性引物，建立了A. ochraceus的qPCR检测方法，该方法最低检测限为30 fg/μL。同时基于PKS基因设计了引物和探针，建立了检测A. ochraceus的RPA检测方法，该方法最低检测限为3 fg/μL，qPCR和RPA检测方法特异性均很强，能够快速检测A. ochraceus污染的食品。对所获得的香辛料中OTA基础污染数据研究了参数拟合与非参数Bootstrp抽样技术，采用Montel Carlo模拟和Bootstrap自抽样技术进行了基于我国人群特点的概率膳食摄入暴露量和风险描述评估，结果表明对当前我国不同年龄人群和不同地区人群由香辛料中摄入OTA引起的健康风险很小，但鉴于香辛料中OTA的11.3%的总体污染率及辣椒中30.0%、花椒和八角中2.0%的污染率应继续对香辛料中OTA进行持续跟踪研究。该研究对掌握我国香辛料中霉菌分布、真菌毒素累积规律及风险控制提供了十分重要的数据与依据。