Aflatoxin M1 in Africa: Exposure Assessment, Regulations, and Prevention Strategies - A Review.

Aflatoxins are the most harmful mycotoxins causing health problems to human and animal. Many acute aflatoxin outbreaks have been reported in Africa, especially in Kenya and Tanzania. When ingested, aflatoxin B1 is converted by hydroxylation in the liver into aflatoxin M1, which is excreted in milk of dairy females and in urine of exposed populations. This review aims to highlight the AFM1 studies carried out in African regions (North Africa, East Africa, West Africa, Central Africa, and Southern Africa), particularly AFM1 occurrence in milk and dairy products, and in human biological fluids (breast milk, serum, and urine) of the populations exposed. Strategies for AFM1 detoxification will be considered, as well as AFM1 regulations as compared to the legislation adopted worldwide and the assessment of AFM1 exposure of some African populations. Egypt, Kenya, and Nigeria have the highest number of investigations on AFM1 in the continent. Indeed, some reports showed that 100% of the samples analyzed exceeded the EU regulations (50 ng/kg), especially in Zimbabwe, Nigeria, Sudan, and Egypt. Furthermore, AFM1 levels up to 8,000, 6,999, 6,900, and 2040 ng/kg have been reported in milk from Egypt, Kenya, Sudan, and Nigeria, respectively. Data on AFM1 occurrence in human biological fluids have also shown that exposure of African populations is mainly due to milk intake and breastfeeding, with 85-100% of children being exposed to high levels. Food fermentation in Africa has been tried for AFM1 detoxification strategies. Few African countries have set regulations for AFM1 in milk and derivatives, generally similar to those of the Codex alimentarius, the US or the EU standards.

Characterization of filamentous fungi isolated from Moroccan olive and olive cake: toxinogenic potential of Aspergillus strains.

During the 2003 and 2004 olive oil production campaigns in Morocco, 136 samples from spoiled olive and olive cake were analyzed and 285 strains were isolated in pure culture. Strains included 167 mesophilic strains belonging to ten genera: Penicillium, Aspergillus, Geotrichum, Mucor, Rhizopus, Trichoderma, Alternaria, Acremonium, Humicola, Ulocladium as well as 118 thermophilic strains isolated in 2003 and 2004, mainly belonging to six species: Aspergillus fumigatus, Paecilomyces variotii, Mucor pusillus, Thermomyces lanuginosus, Humicola grisea, and Thermoascus aurantiacus. Penicillium and Aspergillus, respectively, 32.3 and 26.9% of total isolates represented the majority of mesophilic fungi isolated. When considering total strains (including thermotolerant strains) Aspergillus were the predominant strains isolated; follow-up studies on mycotoxins therefore focused primarily on aflatoxins (AFs) and ochratoxin A (OTA) from the latter strains. All isolated Aspergillus flavus strains (9) and Aspergillus niger strains (36) were studied in order to evaluate their capacity to produce AFs and OTA, respectively, when grown on starch-based culture media. Seven of the nine tested A. flavus strains isolated from olive and olive cake produced AF B1 at concentrations between 48 and 95 microg/kg of dry rice weight. As for the A. niger strains, 27 of the 36 strains produced OTA.

Production of Toxic Metabolites by Penicillium italicum and P. digitatum Isolated from Citrus Fruits.

Ninety-six mold isolates were obtained from naturally rotten citrus fruits. Among them, forty were identified as Penicillium italicum and twenty-four as P. digitatum . Twenty-four isolates of the former and twenty of the latter were tested for toxigenesis. They were first grown on Yeast Extract Sucrose (YES) broth for ten d at 22°C. Then, after mycelium removal, the cultures were sterilized by Millipore filtration and the toxicity of the sterile filtrates tested by four different bioassays; i.e. a bacterial test with Bacillus megaterium , a plant test with Lepidium sativum , a test with the brine shrimp Anemia salina and the chick ( Gallus domesticus ) embryo test. In P. digitatum , 95% of the filtrates were toxic to B. megaterium , 100% caused strong inhibition of seed germination in L. sativum , 75% showed acute toxicity to the brine shrimp and 65% were toxic to the chick embryo, while the figures for P. italicum filtrates were about 96%, 71%, 87%, and 42%, respectively. The results observed with the four different tests didn't always correlate.

Method to Study Antimicrobial Effects of Essential Oils: Application to the Antifungal Activity of Six Moroccan Essences.

The Micro-atmosphere method of Kellner and Kober was modified and used to study antifungal properties of six essential oils that have different chemical compositions (three chemotypes from mugwort, Artemisia herba alba , one from thyme, Thymus capitatus , one from rosemary, Romarinus officinalis and one from Eucalyptus, Eucalyptus globulus ). They were tested against 39 mold strains (13 from the genus Penicillium , nine from Aspergillus and 17 others). The essential oil from thyme was the most effective, suscessively followed by those from mugwort, rosemary and eucalyptus. The strains studied were classified into three groups: sensitive, intermediate and resistant.