Efficiency of biologically and locally manufactured silver nanoparticles from Aspergillus niger in preventing Aspergillus flavus to produce aflatoxin B1 on the stored maize grains

This study was conducted in the mycotoxins laboratory, College of Agricultural Engineering Sciences, University of Baghdad, Iraq to evaluate the efficiency of silver nanoparticles manufactured locally and biologically by Aspergillus niger in preventing A. flavus to produce aflatoxin B1 (AFB1). The results of laboratory isolation showed that the companion of fungi genera were Aspergillus spp., Fusarium spp., Penicillum spp. and Rhizopus spp. at rates of 5.66, 14.91, 21.18 and 38.86% respectively. The highest frequency of A. flavus was 19.32%. The results of the TLC test showed that all isolates produced AFB1 in varying rates (%), and the Baghdad / Al-Youssifia isolate was the most productive of AFB1, since it has a largest spot area and most intense fluorescence under the chromatographic plate, hence given a symbolic name AFBY7. The results of HPLC showed that the toxin concentration in the AFBY7 isolate was 124.167 ppb. Also, the results showed the high efficiency of A. niger in the manufacture of silver nanoparticles, as the colour of solution changed from yellow to dark brown. On the other hand, the results of using locally and biologically manufactured silver nanoparticles in the storage experiment to prevent the fungus from producing toxin showed superiority of treatments (T) 0.4, 0.6 and 0.8 mg L-1, since AFB1 was 0.0 ppb compared to T0.2 (3.990 ppb). In addition, the results showed the efficiency of locally and biologically manufactured silver nanoparticles used in reducing AFB1 in the storage experiment of maize grains stored. So that, T0.6 and T0.8 were superior in reducing the AFB1 to 0.0, compared to T0.2 and T0.4, leading AFB1 to reach 10.230 and 5.180 ppb respectively.