DIVERSITY OF FEEDSTUFF MYCOBIOME IS DETERMINED BY FEEDSTUFF COMPOSITION AND CULTURING CONDITIONS

Abstract

Fungal contamination of feedstuffs is a serious threat impacting domestic animals via the production of mycotoxins. This study surveys the mycobiome diversity of some Egyptian feedstuffs in relation to the type of feed and some culturing conditions viz. type of nutrient medium and incubation temperature. Poultry, rabbit and cattle feeds from the Nile Delta, Egypt were assayed for nutritional components and fungal contamination. Feed inoculants were incubated on potato dextrose agar (PDA) and malt extract agar (MEA) at 25 °C and 30 °C to specify the appropriate culturing conditions for each feedstuff mycobiome. Poultry feed was relatively rich in protein, insoluble sugars and fat; cattle feed was rich in soluble sugars, fiber, moisture and ash; while rabbit feed had moderate composition. PDA rather than MEA favored maximal species richness, species diversity and germ load of feedstuffs. Despite its low fungal count, rabbit feed has high species diversity and species richness but cattle feed exhibited the opposite pattern. The most dominant fungal division was the Ascomycota, particularly Aspergillus spp. and Monascus ruber, followed by Zygomycota with a rarity of Basidiomycota. Some fungal species were confined to certain feedstuffs. The three fungal divisions exhibited different preferences for incubation temperature and nutrient medium. The low moisture content and fungal load refer to the hygienic nature of feedstuffs. Nevertheless, the prevalence of Aspergillus species points to a potential mycotoxin production. Each feedstuff has a unique fungal community, which is further screened by the culturing conditions. The species diversity and species richness of a feedstuff might contrast its fungal count. This study pays attention towards the consequences of seeping of mycotoxins, produced by the feed-born fungi, into the food chain from domestic animals to the humans.