Thirty four fungal species belonging to thirteen genera were isolated, and identified from three animal feeds (crushed corn grains, crushed cotton seeds, and crushed wheat grains), stored at different temperatures for different periods (5, 10, 20, 30, 40, 50, and 60 days), the dominant fungal species isolated from each utilized animal feed were belonged to the genus Aspergillus. The effect of different temperatures on the average count of fungal species associated with each tested animal feed was studied. The production of aflatoxin B1 (AFB1) by the dominant isolated Aspergillus isolates were estimated in vitro using Enzyme Linked Immuno Sorbent Assay (ELISA). The inhibitory effect of different essential oils of some aromatic plants (Cymbopogon citratus Stapf, Eucalyptus globules L., Syzygium aromaticum L., and Ocimum basilicum L.) at different concentrations (0.1, 0.15 and 0.25%) were tested on mycelial dry weight (mg) and AFB1 produced by the tested Aspergillus isolates in vitro. The mycelial dry weight (mg) was decreased with increasing of the concentrations of the tested essential oils. The amount of AFB1 produced by A. flavus (isolates 8, and 10) was completely inhibited by Cymbopogon citratus at 0.25% concentration, while the amount of AFB1 produced by A. fumigatus (isolate 12) was inhibited to 95.1% compared to the control. When the tested animal feeds were amended with the different tested essential oils, and inoculated with the high producer Aspergillus spp., at 26-28ºC for 8 days, Cymbopogon citratus at 0.25% concentration completely inhibited the production of AFB1.
Key words: Animal feeds, temperature, Aspergillus spp., Aflatoxin B1, Essential oils.
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