Abstract
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.
Highlights
Worldwide mycotoxin contamination of agricultural commodities by members of the Aspergillus genus, especially A. flavus and A. parasiticus, has been reported (Dutta and Das, 2001; Ghiasian and Maghsood, 2011; Ibrahim et al, 2016)
It has been reported that ingredients used in animal feed formulations can be contaminated by molds that are capable of producing aflatoxins (Gelven, 2010)
Our findings showed that most of the isolates from our feed samples belonged to subgenera Fumigati and Circumdati based on observed morphological characteristics
Summary
Worldwide mycotoxin contamination of agricultural commodities by members of the Aspergillus genus, especially A. flavus and A. parasiticus, has been reported (Dutta and Das, 2001; Ghiasian and Maghsood, 2011; Ibrahim et al, 2016) These two species, together with A. nomius, are well known producers of the mycotoxin, aflatoxin, a secondary metabolite (Rodrigues et al, 2011; Monson et al, 2015). Biosynthesis of aflatoxins involves participation of several enzymes and regulatory proteins whose genes are found in a single cluster of 70–75 kb in size The order of these genes in Aspergillus is highly conserved (Woloshuk and Prieto, 1998; Yu et al, 2004; Adhikari et al, 2016). The inability to produce aflatoxins by some species is mainly due to mutations in at least one of the genes in the aflatoxin biosynthetic gene cluster (Degola et al, 2007; Adhikari et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
