1 DiSTAS Department for Sustainable Food Process, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy
2 Laboratory of Mycology, Department of Earth, Environmental and Life Sciences, Università degli Studi di Genova, Corso Europa 26, I, 16136 Genova, Italy
Ochratoxin A is a nephrotoxin which may occur in wines characterised by higher pH than the average. In the last decades the mechanisms responsible for ochratoxin A reduction by lactic acid bacteria have been investigated and identified as mainly cell walls adsorption and / or enzymatic conversion to ochratoxin-α, a non-toxic metabolite. Since lactic acid bacteria are involved in the malolactic fermentation during the wine-making process, selected starter cultures could be exploited to guarantee safe ochratoxin A level in wines also from contaminated grapes. A lactic acid bacteria strain (Lactobacillus plantarum V22) was previously selected for its ability of both degrading ochratoxin A and carrying out malolactic fermentation at high pH.
This study was aimed at assessing if the selected L. plantarum strain, can reduce ochratoxin A because it can use it as a carbon source.
L. plantarum V22 was grown in the presence of ochratoxin A in two different synthetic substrates, with or without malic acid, monitoring the reduction of ochratoxin A and the presence of ochratoxin α as an indicator for a toxin enzymatic hydrolysis. The presence of residual not hydrolysed ochratoxin A bound to the bacteria cell walls was also evaluated to quantify the ochratoxin A removal due to simple adsorption.
A significant reduction of 19.5 ± 2.0% in ochratoxin A concentration was observed only in the presence of malic acid. The quantified fraction of ochratoxin A adsorbed on cell walls was irrelevant and the metabolite ochratoxin α could not be detected.
There is a possibility that L. plantarum V22 can degrade ochratoxin A through a not yet identified metabolic pathway.
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