Ochratoxin A released back into the medium by Saccharomyces cerevisiae as a function of the strain, washing medium and fermentative conditions.
BACKGROUND
This study was aimed at investigating the removal of ochratoxin A (OTA) by two wild strains of Saccharomyces cerevisiae (W20 and W30) in a semi-synthetic medium under two temperatures (25, 30 °C) and sugar levels (200, 250 g L(-1) ), as well as the stability of OTA-yeast complex by evaluating the amount of bound toxin released back after some washing treatments with phosphate-buffered saline (PBS) or model wine (MW). In addition, the main products of fermentation were studied.


RESULTS
Both W20 and W30 strains reduced OTA with removal percentages of 5.41-49.58%, and this process was affected by temperature and sugar concentration. Concerning the stability of the OTA-yeast complex, the amount of bound toxin decreased by 20-99% after five passes of washing, with a strong strain dependence and an effect of temperature and sugar concentration only for the W30 isolate. In addition, the two strains showed interesting technological properties in terms of fermentation products in a semi-synthetic medium (high ethanol yield, volatile acidity as acetic acid < 1.2 g L(-1) ; glycerol production exceeding 5.2 g L(-1) ).


CONCLUSIONS
Apart from the removal of OTA, release of the toxin is a variable process and relies upon the strain effect; a significance of the other factors of the design (sugar concentration, temperature) was found only for a single isolate. Thus evaluation of the stability of the complex yeasts/OTA should be an additional trait to select promising functional yeasts.
Department of the Science of Agriculture, Food and Environment, University of Foggia, Via Napoli 25, 71122, Foggia, Italy.
Antonio
A
Bevilacqua
Leonardo
L
Petruzzi
Maria Rosaria
MR
Corbo
Antonietta
A
Baiano
Carmela
C
Garofalo
Milena
M
Sinigaglia
D003470:Culture Media; D005285:Fermentation; D005506:Food Contamination / Q000517:prevention & control*; D005638:Fruit / Q000737:chemistry; D009793:Ochratoxins / Q000032:analysis / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013045:Species Specificity; D013696:Temperature; D027843:Vitis; D014920:Wine / Q000032:analysis / Q000382:microbiology
D003470:Culture Media; D009793:Ochratoxins; C025589:ochratoxin A
Saccharomyces cerevisiae; alcoholic fermentation; ochratoxin A release; ochratoxin A removal; wine