José, PÉREZ-NAVARRO1, Tania, PANIAGUA MARTÍNEZ, Pol, GIMÉNEZ2, Joan Miquel, CANALS, Fernando, ZAMORA, Sergio GÓMEZ-ALONSO1,
1 Regional Institute for Applied Scientific Research (IRICA), University of Castilla-La Mancha, Av. Camilo José Cela 10, 13071 Ciudad Real, Spain. Faculty of Chemical Sciences and Technologies, University of Castilla-La Mancha, Av. Camilo José Cela, 10, 13071 Ciudad Real, Spain
2 Faculty of Chemical Sciences and Technologies, University of Castilla-La Mancha, Av. Camilo José Cela, 10, 13071 Ciudad Real, Spain
3 Faculty of Oenology, University of Rovira I Virgili, C/Marcel.li Domingo s/n, 43007 Tarragona, Spain.
Email contact: jose.pnavarro[@]uclm.es
AIM: This study evaluates the effect of different oenological factors and natural mediators on the degradation of Ochratoxin A (OTA) using Botrytis cinerea laccase. Because of its risk to human health, different detoxification techniques have been developed in various kinds of foodstuffs. The use of fungal or bacterial laccases is a biological method to decrease the OTA concentration [1, 2]. Laccases can oxidize a wide range of substrates, some of which cannot be oxidized directly by these enzymes and require the use of redox mediators . Due to this, several natural mediators present in wine and different SO2 and ethanol concentrations were tested in the current work.
METHODS: The ability of laccase to degrade OTA was studied by incubation of the enzyme in acetate buffer pH 4.0 and model wine, with OTA and mediators at 28 ºC during 24 h. To determine the impact of SO2 and ethanol on the OTA degradation caused by laccase, different concentrations of SO2 (10, 20 and 30 mg/L) and ethanol (5, 10 and 15% v/v) were used. The quantification of this mycotoxin was carried out in a HPLC-QTOF-MS system.
RESULTS: Under these conditions, OTA cannot be oxidized directly by laccase from Botrytis cinerea and the use of redox mediators is required. Among natural mediators tested, (-)-epicatechin and (+)-catechin were the phenolic compounds with higher impact on the biodegradation of this mycotoxin, achieving a decrease of OTA concentration over 50%. The degradation of OTA was completely inhibed by 30 mg of SO2/L, while 20 mg of SO2/L reduced lacasse activity by a half and 10 mg of SO2/L hardly caused any effect on the biodegradation of this mycotoxin. A concentration of 15% of ethanol led to a 50% reduction in the activity of laccase over OTA.
CONCLUSIONS: These preliminary results may be a first step in finding biological alternative strategies to eliminate undesirable substances such as mycotoxins (OTA) present in wine.
1. Chen W, Li C, Zhang B, Zhou Z, Shen Y, Liao X, Yang J, Wang Y, Li X, Li Y, Shen XL. 2018. Advances in biodetoxification of ochratoxin A-A review of the past five decades. Frontiers in Microbiology 9:1386.
2. Loi M, Fanelli F, Liuzzi V, Logrieco A, Mulè G. 2017. Mycotoxin biotransformation by native and commercial enzymes: Present and future perspectives. Toxins 9:111.
3. Gunne M. 2014. Identification and optimization of novel bacterial laccases. Ph.D. Thesis. Heinrich-Heine-Universität Düsseldorf.