Table_2_Biodiversity of Aflatoxigenic Aspergillus Species in Dairy Feeds in Bulawayo, Zimbabwe.docx

The presence of molds, especially certain species of Aspergillus, in food commodities may contribute to aflatoxin contamination. The aim of this study was to determine the biodiversity of Aspergillus species in dairy feeds from farms in select locations in Zimbabwe and assess their aflatoxin production potential using a polyphasic approach. A total of 96 feed samples were collected, which consisted of dairy feed concentrate, mixed ration, brewers’ spent grain, and grass from 13 farms during the dry season (August–October, 2016) and the following rainy season (January–March, 2017). A total of 199 presumptive isolates representing four sections from genus Aspergillus (Nigri, Fumigati, Flavi, and Circumdati) were recovered from the feeds. Section Flavi, which includes several aflatoxin producers, constituted 23% (n = 46) of the isolates. Species from this section were A. flavus, A. nomius, A. oryzae, A. parasiticus, and A. parvisclerotigenus, and 39 (84.4%) of these showed evidence of aflatoxin production in plate assays. Of the 46 section Flavi isolates examined, some lacked one or more of the five targeted aflatoxin cluster genes (aflD, aflR, aflS, aflM, and aflP). The presence of the five genes was as follows: aflD (76.9%), aflR (48.7%), aflS (74.4%), aflM (64.1%), and aflP (79.5%). This study highlights the species diversity of aflatoxigenic fungi that have the potential to contaminate different types of feed for dairy cows. Our findings underscore the importance of preventing contamination of feedstuffs by these fungi so that aflatoxins do not end up in the diets of consumers.

饲料原料中霉菌（尤其是特定曲霉属（Aspergillus）物种）的存在可能会引发黄曲霉毒素（aflatoxin）污染。本研究旨在探明津巴布韦部分选定地区农场的奶牛饲料中曲霉属物种的生物多样性，并采用多相分类法（polyphasic approach）评估其产黄曲霉毒素潜力。本研究于旱季（2016年8月—10月）及后续雨季（2017年1月—3月）从13家农场采集了共计96份饲料样本，样本涵盖奶牛浓缩饲料、混合日粮、啤酒糟以及牧草。从上述饲料中共分离得到199株疑似菌株，分属于曲霉属的四个组群：黑曲霉组（Nigri）、烟曲霉组（Fumigati）、黄曲霉组（Flavi）以及赭曲霉组（Circumdati）。其中包含多种产毒菌株的黄曲霉组菌株占分离菌株总数的23%（共46株）。该组菌株包括黄曲霉（A. flavus）、名义曲霉（A. nomius）、米曲霉（A. oryzae）、寄生曲霉（A. parasiticus）以及小核曲霉（A. parvisclerotigenus），其中39株（占比84.4%）在平板检测（plate assays）中表现出产黄曲霉毒素的特性。在检测的46株黄曲霉组菌株中，部分菌株缺失了靶向黄曲霉毒素合成基因簇的5个目标基因：aflD、aflR、aflS、aflM及aflP。这5个基因的检出率分别为：aflD（76.9%）、aflR（48.7%）、aflS（74.4%）、aflM（64.1%）以及aflP（79.5%）。本研究揭示了可污染不同类型奶牛饲料的产黄曲霉毒素真菌的物种多样性。本研究结果凸显了防范此类真菌污染饲料原料的重要性，以避免黄曲霉毒素最终进入消费者的膳食链条。