Abstract: Dried fruits contain protein, carbohydrate, dietary fiber, vitamins, minerals and antioxidants. Antioxidants work to prevent cancer, stroke, heart disease, cataracts, and other diseases associated with ageing. Dried fruits can be contaminated with several kinds of fungi that produce mycotoxins such as aflatoxins, ochratoxin A, patulin and zearalenone.
Objectives: The study aimed to determine the species of toxicogenic fungi most common on dried fruits and in living premises and to evaluate their abilities to produce secondary metabolites dangerous for human health, to evaluate mycobiota capabilities to produce mycotoxins in their cultural media, to set up a DNA-based method for detecting aflatoxigenic fungi Aspergillus species isolated from dried fruits using species-specific primers to increase the awareness of mycotoxins in foods by developing fast and rapid mycotoxin diagnosis kits that are easy and economical to use and enhance the awareness of mycotoxins.
Methods: 15 types of dried fruits were collected from many markets in different areas in the Kingdom of Saudi Arabia which produced in different countries. All two groups were distributed, first group were surface disinfected by dipping with sodium chloride for 3 minute and washed several times with sterilized water, after that we put sterilized fruits on Petri- dish containing Potato dextrose agar (PDA). Second group of dried fruits were put on PDA without surface sterilization. The PDA and Cazpek's-Dox agar media were used for the pathogen inoculation. For identification of fungi and their mycotoxins was used different types of methods such as single spore isolation technique, UV light screening test for mycotoxins production, ELISA, HPLC as well as PCR.
Results: Raisins (grape) gave the highest total number of fungi isolates while the lowest number of fungi isolates was given by fig and the mango and the highest number of fungi isolates was produced from the non-sterilized dry fruits, while raisins yielded the highest number of fungi, the dried Mango yielded the lowest number. Also results found that Aspergillus niger showed the highest isolation frequency (50.8%) and Aspergillus flavus isolation frequency was (19.5%).
Determination of the mycotoxins produced from 26 isolates of Aspergillus species which isolated from different dried fruits by ELISA, found that while Aspergillus flavus from coconut yield all the 6 toxins, the isolate of Aspergillus niger which isolated from date did not produce any kind of toxins.
The PCR was used for the detection of mycotoxigenic species. The test was performed with an optimized protocol for dried fruits which includes a set of species- specific PCR assays. Specific PCR assays were developed to detect A. flavus or A. niger. A specific detection of A. flavus and A. niger using DNA obtained.
Conclusion: High level of genetic variability among non-aflatoxigenic A. flavus isolates that require greater attention in order to design a molecular experiment to distinguish true aflatoxigenic from non-aflatoxigenic A. flavus strains.
Keywords: Fungi, Dried Fruits, mycotoxins, ELISA, HPLC, PCR.
Title: Identification of Toxigenic Fungi Recovered from Dried Fruits
Author: Hanan Alomari, Ali H. Bahkali
International Journal of Life Sciences Research
ISSN 2348-313X (Print), ISSN 2348-3148 (online)
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