Detecting the Activity of Silver Nanoparticles, Pseudomonas Fluorescens and Bacillus Circulans on Inhibition of Aspergillus Niger Growth Isolated From Moldy Orange Fruits

Abstract

The improper packaging and storage of oranges (Citrus sinensis) may result in decay it and growth of microorganisms, including Aspergillus spp. these fungi are omnipresent and growing on post-harvest fruits. Certain species of Aspergillus produce toxins that can affect humans and animals health. This study aimed to isolate Aspergillus niger from moldy oranges, test its ability to produce aflatoxin using the Saito and Machida method, and evaluation of their toxicity of some biochemical parameters in white rat males. Moreover, the inhibition efficiency of silver nanoparticles (AgNPs), Pseudomonas fluorescens, and Bacillus circulans were assessed against A. niger isolates. The outcome of screening all nine isolates by the Saito and Machida method has shown the capability of one isolate to produce aflatoxins in large amounts. The filtrate of this isolate showed an increase in the level of GPT and GOT enzymes (24.2 U/ml and 18.3 U/ml) respectively, compared to the non-producing aflatoxins isolate and the control (16.6 and 12.2 U/ml) and (8.5 and 8.2 U/ml) respectively. Glucose level was increased to (130.2 mg/dl) in the rats treated with the filtrate of aflatoxins producer isolate compared to (95 mg/dl) and (86.4 mg/dl) treated with the filtrate of the non-producer isolate and the control respectively. Additionally, the LDL-cholesterol level was reduced to 120.2 mg/dl, and 101 mg/dl with the filtrate producer and the non-producer aflatoxins isolates respectively compared to 144.3 mg/dl for the control. AgNPs have shown an inhibitory effect against A. niger growth with the largest inhibition zone of 28.38 mm at a concentration of 100μl was recorded. On the other hand, Pseudomonas fluorescens and Bacillus circulans have also shown an excellent inhibition rate (100%) at the concentration of 2 g/L of the fungus filtrate. These results exposed that AgNPs are able to inhibit A. niger, and consequently, AgNPs can be used as an antifungal candidate.

Antimicrobial properties of nanoparticles in biofilms

“…Many products, including toothpaste, now incorporate powdered zinc citrate or acetate to control the formation of dental plaque. Metallic nanoparticles have also been considered to improve antimicrobial efficiency [47][48][49][50] .…”