Document Details

Document Type : Article In Journal 
Document Title :
“Control of Aspergillus flavus in corn using natural materials”
"مقاومة فطر الأسبرجلس فلافس فى الذرة باستخدام المواد الطبيعية"
Document Language : English 
Abstract : Control of Aspergillus flavus in corn using natural materials I would like to thank SfAM for awarding me a President’s Fund grant to attend the 9th European Conference on Fungal Genetics held in Edinburgh, UK on 5-8 April 2008. I presented my paper on the organisms that produce the mycotoxin, aflatoxin, especially Aspergillus flavus. This can infect important food and feed crops, including corn, before, during and after harvest. These fungi are normal soil-borne inhabitants in our environment, growing on both living and decaying plant matter. Mycotoxins include metabolic by-products produced by a number of different fungi. The importance of this study comes from the prevalence of Aspergillus flavus producing aflatoxin in corn, wheat and barley crops. It is possible to control contamination by preventing the presence of the fungus (Aspergillus flavus) and removing or affecting its capability to produce the toxin. This could be done by using natural materials and may lead to the production of toxinfree food and feed and increased safety from a health point of view whilst preserving grain food wealth. I studied the control of Aspergillus flavus using natural materials namely, the essential oil marjoram (Origanum majorana L.) and salt (sodium chloride) and their effect on fungal growth and the quantity of aflatoxin production. Effect of different concentrations of marjoram (Origanum majorana L.) essential oil and salt (sodium chloride) on Aspergillus flavus: One millilitre of Aspergillus flavus containing 5.0x104cfu/ml was added to 100 grams of corn (sterilized in a 250 ml conical flask) and distributed without the addition of marjoram or salt (control sample). Also, one millilitre of the same Aspergillus flavus with the addition of different volumes of marjoram essential oil (0.05, 0.1, 0.2, 0.3, 0.5 and 0.7 ml) and one ml of the same Aspergillus flavus with the addition of different weight of salt (0.2, 0.4, 0.6, 1.0, 1.5 and 2.0 grams) were each added to 100 grams of sterilized corn (placed in a 250 ml sterilized conical flask) and mixed. Sterilised distilled water was added to raise the moisture content to 18% and the mixture was shaken to make it homogenous. These were stored at 25OC for 21 days. Sampling to determine Aspergillus flavus count and aflatoxin concentration was made at intervals of 7 days until 21 days. Adding 0.05 ml of marjoram essential oil did not stop the growth of Aspergillus flavus during storage and up to 21 days, in inoculated corn. At the beginning of storage Aspergillus flavus count was 4.0x102 cfu/g and gradually increased on day 21 to reach 1.5x103cfu/g. The corresponding values in the control sample were 4x102 Aspergillus flavus count and 0 ppb aflatoxin production at the beginning of storage and 3.2x103 Aspergillus flavus and 150 ppb aflatoxin production at the end of storage (21 days). This indicates that the addition of 0.05 ml marjoram caused a reduction of Aspergillus flavus count of 62.5% at 21 days of storage. Raising the level of marjoram to 0.1 ml inhibited the growth of Aspergillus flavus and aflatoxin production completely at 7 days until the end of storage. These results are in agreement with those of Paster et al., (1995) who reported that the essential oil of marjoram has been shown to inhibit mycelial growth and aflatoxin production in Aspergillus parasites and Aspergillus flavus — both fungi which grow on stored grains. This observation was noted clearly with other higher marjoram levels. It can be observed from the effect of different salt concentrations on A. flavus count during storage of inoculated corn up to 21 days that the control sample gave a gradual increase in A. flavus number during storage from 0 to 21 days. It increased from 6x102 cfu/g to 5x103cfu/g at 0 and 21 days storage period respectively. The corresponding values, in inoculated corn sample treated with 0.2 grams of salt were 6x102cfu/g to 9x102cfu/g at the same periods of storage. Although the salt concentration (0.2 gram) was quite low it still produced a slight effect towards reducing the rate of growth of A. flavus during storage. This trend increased during storage, and was more obvious when 0.4 grams of salt was added. At this concentration the number of A. flavus at 0, 7, 14 and 21 days storage period became 6x102, 6.3x102, 6.6x102 and 7x102cfu/g, respectively. At 0.6% salt concentration growth inhibition reached 83.3% and aflatoxin production reached 50 ppb between 0 and 21 days while the control sample reached 180 ppb during the same period. Hence this concentration is not suitable for controlling A. flavus growth during storage. Raising salt concentration to 1 gram caused a complete inhibition of A. flavus growth and aflatoxin production during the whole experimented storage periods (7, 14, and 21 days). The same observation was noted when 1.5 and 2 grams of salt were used. Accordingly the minimum inhibitory concentration to prevent A. flavus growth in corn is 1 gram salt/100 gram corn and can be successfully used in the storage of corn up to 21 days. It is also suitable to prevent aflatoxin production. Moreover salt is traditionally used as a food, feed ingredient and food preservative, so the hazard would appear negligible. It is possible to conclude that using marjoram at concentration of 0.1 ml and above per 100g corn at 18% moisture inhibited the growth of Aspergillus flavus completely at 7 days and up to the end of storage also prevented aflatoxin production. Also it can be concluded that the minimum inhibitory concentration to prevent A. flavus growth in corn is 1 gram salt/100 gram corn. This concentration can be successfully used in the storage of corn up to 21 days. It is also suitable to prevent aflatoxin production. 
ISSN : 1479-2699 
Journal Name : Microbiologist 
Volume : 10 
Issue Number : 3 
Publishing Year : 1430 AH
2009 AD
Article Type : Article 
Added Date : Saturday, September 10, 2011 


Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
يوسف أحمد جبريلGibriel, Youssef


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