* Corresponding author e-mail: abdallahhassane@yahoo.com © 2017 NSP Natural Sciences Publishing Cor. J. Eco. Heal. Env. 5, No. 3, 77-83 (2017) 77 Journal of Ecology of Health & Environment An International Journal http://dx.doi.org/10.18576/jehe/050302 Influence of Different Moisture Contents and Temperature on Growth and Production of Aflatoxin B 1 by a Toxigenic Aspergillus flavus Isolate in Wheat Flour A. M. A. Hassane 1* , A. A. El-Shanawany 1 , N. F. Abo-Dahab 1 , A. M. Abdel-Hadi 1,2 , U. M. Abdul-Raouf 1 and M. Mwanza 3 . 1 Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Assiut Branch, 71524 Assiut, Egypt. 2 College of Applied Medical Sciences, Medical Laboratories Department, Majmaah University, Kingdom of Saudi Arabia. 3 Department of Animal Health, Faculty of Agriculture and Technology, Mafikeng Campus, North West University, Private Bag X2046,Mmabatho 2735, South Africa. Received: 21 Jul. 2017, Revised: 22 Aug. 2017, Accepted: 24 Aug. 2017. Published online: 1 Sep. 2017. Abstract: Experimental short time population and production of aflatoxin B1 by Aspergillus flavus in wheat flour at 20, 25, 30, 35 and 40ºC, as related to different moisture contents 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22% and 25%, was studied. Spore suspension of a toxigenic A. flavus containing ~ 3×10 3 spore/ml was inoculated in each flask containing 50 g wheat flour and incubated for 15 days. Spore count was observed slightly in flour with a moisture content 5% at all incubation temperature, then increased gradually by rising the moisture content reaching the maximum at 30ºC with moisture content 25%. High performance liquid chromatography analysis of AFB1 showed the lowest quantification (482 ng/kg) at 20ºC with 8% moisture content in comparison to uninoculated control. The higher quantity of AFB1 (637835.4 ng/kg) was produced at 25ºC with 25% moisture content. Accumulation of high amounts of AFB1 was noticed at 20, 30 and 35ºC with moisture content 25%. However, at 40ºC with moisture contents 22% and 25%, high spore count was recorded, but traces of AFB1 were produced. The significance of this investigation is that, in the event of wheat flour contamination with afltoxigenic species, rise in moisture contents are hazardous in the storage of wheat flour around 25ºC. Keywords: Moisture contents, temperature, Aspergillus flavus, aflatoxin B1, wheat flour. 1 Introduction Aflatoxins (AFs) are secondary metabolites biosynthesized by numerous species of Aspergillus, especially A. flavus and A. parasiticus [1]. Not all A. flavus and A. parasiticus strains are aflatoxins producers, but about 60% of isolates were producer [2]. There are four major types of aflatoxins; B1, B2, G1 and G2 based on their fluorescence under UV light, and their two metabolites M1 and M2. However, the most harmful mycotoxin at present known is AFB1. Naturally A. flavus produces aflatoxins AFB1 and AFB2, while A. parasiticus produces the four aflatoxins types [3]. Aflatoxins are highly toxic, mutagenic and carcinogenic compounds and chemically, they are a group of difuranocoumarin derivatives [4]. Aflatoxins biosynthesis is the outcome of a mix of species, substrate and environment. The factors influencing AFs production can be divided into three categories: physical, nutritional and biological factors. Physical factors include temperature, pH, relative humidity of the atmosphere, water activity, moisture, light, aeration and level of atmospheric gases [5]. The development of A. flavus and aflatoxin biosynthesis relies upon favorable conditions of temperature and humidity [6]. The conditions conducive to germination, growth and aflatoxin production by A. flavus and A. parasiticus demonstrate that germination happens over a wider range than that for growth, with the aflatoxin production range yet narrower than that for growth [7]. Optimal conditions of nutrition and physiological parameter changes for various strains [8]. There are numerous examinations about the best conditions for fungal development and toxin biosynthesis. Some contrasting