Analysis of aflatoxin M1 contamination in milk and cheese produced in Mexico: a review

Due to the carcinogenic character of aflatoxins when present in foods, these compounds are considered a risk to human health. This systematic review aimed at compiling the available research data on detection and quantification of aflatoxin M1 (AFM1) in milk and common types of cheese produced in Mexico in the past two decades. A limited number of studies were found that matched the purpose of our review. Only ten research works focused on the evaluation of AFM1 content in milk while three studies analysed the occurrence of this mycotoxin in oaxaca and panela cheeses. HPLC-FD and ELISA were the methods of choice utilised to detect AFM1. Concentrations higher than 0.5 μg AFM1/kg, a maximum limit set in current food regulation in Mexico, were found in major dairy brands consumed in Mexico. Analysis of raw milk produced during the rainy season in the states of Jalisco (2007) and Chiapas (2013) showed mycotoxin levels within the regulation limits while milk samples obtained during the dry season in the Mexico City and the State of Mexico (2008) exceeded that threshold. For cheeses, 33% of the artisanal produced oaxaca type samples from Veracruz (2016) and 55% of those acquired in Mexico City (2019) were found above the limit set for milk. In contrast, the panela cheese samples obtained in Baja California and Guanajuato (2009) complied with the AFM1 regulation. Additionally, the presence of AFB1 and its hydroxylated metabolites other than AFM1 were determined in the major milk brands at concentrations that could be of high risk for human health. Similar results were reported for both artisan and industrially produced oaxaca cheese. Finally, mycotoxins enter human food chain through animals fed with contaminated fodder. Our systematic review demonstrated the urgent need to amend the existing food regulation in Mexico to include mycotoxins as potent contaminants in cheese.

The effect of endophytic colonization of wheat plants by the fungus Beauveria bassiana on the development of the nymphs of the migratory and desert locusts

The experiments were aimed at evaluation of the effect of feeding with wheat colonized by the fungus Beauveria bassiana on the development of locusts. The seeds were treated with fungal conidia and 90 days after sowing, the plant parts were fed to II instar nymphs of laboratory colonies of migratory and desert locusts within the period of 18 days. The mortality levels between experimental and control (fed with untreated wheat) groups were not significantly different though a tendency of an increase in variants with contaminated fodder was observed. Two weeks after the beginning of the bioassay, insect mortality was 20-30% and 15% in control. As many as 50% of migratory locust and 40% of desert locust cadavers were covered by a fungal mycelium. Sequencing of two diagnostic DNA loci has confirmed attribution of the reisolate to the genotype of the initial Beauveria bassiana strain BBK-1. It can be therefore concluded that the endophyte fungus is capable of causing classical pathogenesis of mycosis in locust nymphs. Moreover, the nymphal development was retarded by feeding with the fungus-colonized plants.