Abstract

Aflatoxin B1 (AFB1) is a major threat to human and animal health, due to its potent hepatotoxic, carcinogenic and mutagenic effects. Removal or inactivation of aflatoxin in food and feedstuff is difficult. Chemical and physical methods have been found to be effective in detoxification of AFB1 from various materials but their use in the practice is limited, due to safety issues and possible loss of nutritional value of the treated commodities. In the feed industry a proposed technology for detoxification of feedstuff is the dietary supplementation of inorganic or organic materials able to adsorb mycotoxins. Once the mycotoxin has been bound, absorption in the digestive tract of animals is strongly reduced. Some mineral adsorbents such as aluminosilicates, bentonites and activated carbons have showed good results but have some drawbacks, such as the negative impact on the nutritional quality of decontaminated feed. For this reason, interest in the use of natural microbial adsorbents has increased. In this study we investigated the capability of ground not-viable mycelium of the edible and cultivated mushroom Pleurotus eryngii to bind AFB1. P. eryngii strain ITEM 13681 was cultured on malt-extract broth for 20 days at 28 °C in the dark. For preparation of the biosorbent, the mycelium was harvested, autoclaved, lyophilized and finely ground to particles of size <= 500 µm. One hundred milligrams of the biosorbent were suspended in 5 mL of phosphate-buffer saline (PBS) pH 7 containing 2000 ng AFB1, and incubated overnight at 25 °C in a rotary shaker at 250 rpm. Then, the mycelium and the supernatant were separated by centrifugation and both the phases were analyzed for AFB1 content. Sixty-five percent of AFB1 was detected in the supernatant, while the mycelium was able to retain 6 ng of AFB1 per milligram of dry mycelium (35%). The effect of mycelium dosage was studied by testing different amounts of biomass (25, 50, 75, 100, 150, 200 mg/mL) in both acetate buffer (pH = 5) and PBS (pH = 7) containing 0.5 µg/mL AFB1. The suspensions were shaken for 90 minutes at 250 rpm, at 25 and 37 °C. Then the samples were centrifuged at 13000 rpm for 10 minutes and the pellets were washed three times and analyzed by UPLC/FLD. The efficiency of adsorption (%A) was calculated using following equation: %A = [(Ci - Cf) / Ci] x 100; where Ci was the initial and the Cf final concentration (supernatant plus washing solution) of mycotoxin. The biosorbtion showed to be both dosage- and temperature-dependant. In acetate buffer the mycelium adsorbed 44±4% at the dosage of 200 mg and no significant adsorption at 25 mg. In PBS absorption at 37 °C ranged from 7±5% at 25 mg of mycelium to 64±6% at 200 mg, and at 25 °C it ranged from 3±0 % at 25 mg of mycelium to 26±3% at 200 mg. Our results envisage a possible use of P. eryngii as a cheap and effective biosorbent for AFB1. This mechanism of AFB1-binding by P. eryngii mycelium is herein demonstrated for the first time.

Autore Pugliese

• Logrieco Antonio Francesco , Altomare Claudio , Haidukowski Edith Miriam

Tutti gli autori

• Cimmarusti M.T.; Casamassima E.; Branà M.T.; Longobardi F.; Logrieco A.F.; Haidukowski M.; Altomare C.

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Anno di pubblicazione

2017

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