The Safety and Efficacy of Pleurotus ostreatus (Oyster Mushroom) Cultivation on Prosopis spp. Products

Abstract

Improving food safety and food security is imperative to adequately feed a growing population that is expected to exceed 9 billion people by 2050. Mushroom cultivation provides unique opportunities to take advantage of underutilized resources and produce high-quality food from otherwise inedible or unsafe food sources. Pleurotus ostreatus is a ligninolytic and biotechnologically relevant fungus that can be cultivated on a diverse array of lignocellulosic byproducts. Prosopis spp. are abundant in the Sonoran Desert and broadly distributed in semi-arid to arid regions around the globe. Prosopis spp. legumes (pods), and approximately 25% of all commonly cultivated crops, are susceptible to aflatoxin contamination, a highly carcinogenic and potentially lethal mycotoxin. This work aimed to (1) identify novel lignocellulosic byproducts from the Sonoran Desert for use as substrate materials in Pleurotus ostreatus (oyster mushroom) cultivation; (2) evaluate the safety of mushrooms cultivated on plant products that are contaminated with aflatoxin; and (3) measure the amount of aflatoxin that is degraded by P. ostreatus after the contaminated products have been colonized by the fungus. Prosopis spp. pods were identified as suitable substrate component for P. ostreatus production by conducting yield evaluations and finding that the biological efficiency increased with increasing percentages of pods. No detectable quantity of aflatoxin could be measured in mushrooms that were cultivated on maize that was naturally contaminated with aflatoxin B1 at concentrations up to 2500 ng g⁻¹. P. ostreatus degraded AFB₁ by >85% in maize with initial concentrations of 2500 ng g⁻¹ AFB₁ in repeated experiments. Thus, the cultivation of P. ostreatus on aflatoxin-contaminated products may be a viable method to produce a safe and high quality food from an otherwise unsafe food source, and may double as a means to reduce the aflatoxin concentration in contaminated plant products to levels that are acceptable for use as livestock feed.