襄阳市主要花生种植区土壤中黄曲霉菌分布及产毒力研究

Distribution,aflatoxin production of Aspergillus flavus in soils of main peanuts planting areas in Xiangyang China

为掌握襄阳市主要花生种植区土壤中黄曲霉菌的分布和产毒特征,从襄阳市主要花生种植区采集土壤样品36份,进行黄曲霉菌分离、鉴定和产毒力研究。结果表明,襄阳市不同花生种植区土壤中黄曲霉菌落数平均为5997.6 cfu/g,且分布存在显著差异,菌落数由高到低依次为襄州、枣阳、宜城、谷城;鉴定获得黄曲霉菌株中产毒菌株占63.6%,产毒量范围ND~304.9μg/L,不产毒菌株占36.4%;产毒菌株可分为7种产毒类型组合,其中同时产AFB_(1)、AFB_(2)和AFG_(1)三种类型的黄曲霉菌占比最多,为54.0%。在适宜培养条件下,产毒力分析结果为襄州地区每克土壤中黄曲霉菌产AFT的理论值最高,可达2080.0×10^(3)μg/L,且其中分离出的菌株平均产毒量最高,为218.7μg/L。可以看出襄阳市花生代表性产区土壤中黄曲霉菌分布数量显著高于我国南、北方花生主产区的平均水平,但其菌株的平均产毒能力却远低于全国其它地区。本研究初步得出了襄阳市花生主产区黄曲霉菌的分布特征和产毒特征,可为襄阳市花生黄曲霉毒素防控提供理论依据。

In order to investigate the occurrence and distribution of aflatoxin by Aspergillus flavus in soils,36 soil samples were collected from 4 main peanut planting areas in Xiangyang for A.flavus isolation,identification and aflatoxin detection.Results demonstrated that the average colony number of A.flavus was 5997.6 cfu in one gram soil generally.But the populations of A.flavus in soil samples from 4 peanuts areas were significantly different.The order of colony numbers of 4 peanuts areas was Xiangzhou,Zaoyang,Yicheng,Gucheng,ranking from high to low.Among the strains,aflatoxigenic strains accounted for 63.6%,with AFT content of ND-304.9μg/L,and proportion of atoxigenic strains was 36.4%.According to the aflatoxin types,there were 7 types of aflatoxigenic strains and the proportion of strains which producing AFB_(1)+AFB_(2)+AFG_(1) was the highest,reaching 54%.Studies on aflatoxin production in different planting areas showed that with proper culture conditions,the highest amount of AFT contamination per gram of soil was from Xiangzhou,reaching 2080.0×10^(3)μg/L.And the average aflatoxin production of strains isolated from soils of Xiangzhou was the highest(218.7μg/L).Results illustrated that the average population of A.flavus in soil samples from main peanuts planting fields in Xiangyang was significantly higher than that in both south and north peanuts planting areas in China.But the ability of aflatoxin producing of A.flavus isolated from soils in Xiangyang were much lower than those from other areas in China.This study was expected to provide a theoretical base for predicting and controlling of aflatoxin contamination in typical peanut planting areas in Xiangyang.