Degradação de ocratoxina a mediante proteases bacterianas
PINTO, Anne Caroline Schoch Marques1; MECA, Giuseppe3; MINGUEZ, Carlos Luz3; ROIG, Josep Ferrer 3; LUCIANO, Fernando Bittencourt 2;
Introdução:Ochratoxin A (OTA) is a toxin produced by fungal species of the genus Penicillium and Aspergillus, mainly during storage. This toxin is resistant to thermal treatments and, therefore, it is common to find OTA in processed foods and animal feed. It has been classified by the International Agency of Research on Cancer (IARC) as possibly carcinogenic (2B). Due to its toxicity, legislations have been introduced in several countries to regulate its maximum tolerable limits in foods. These limits are in the order of a few parts per billion. Therefore, different methods have been sought to mitigate the possible toxic effects generated by OTA’s presence in foods and animal feed. Lactic Acid Bacteria (LAB) are commonly used in food production as starter cultures or probiotics, and some species have been found to degrade OTA in non-toxic metabolites.
Objetivo:The aim of this project was to evaluate the capacity of 17 LAB to degrade OTA in vitro and in a digestion system that simulates the gastrointestinal tract of pigs.
Metodologia:Firstly, 17 LAB strains were incubated with OTA in MRS broth for 24 h and the levels of the mycotoxin were evaluated by LC-FLD. Strains with the best degradation rates were selected to perform enzymatic tests, using extracellular and membrane-bound enzymes. These enzymes were separately incubated with OTA for 24h at pH 3,5 or 6,5. Moreover, selected strains were tested for their ability to adhere in Caco-2/TC7 cells in vitro, which mimic the intestinal epithelium. Lastly, selected strains were also tested in a simulated system of pig digestion to evaluate their capacity to degrade OTA until the mycotoxin reaches the small intestine.
Resultados:Three selected LAB could degrade 700 to 900 ppb of OTA in vitro. However, in the enzymatic tests and during the digestion simulation, there was no significant reduction of OTA concentration in comparison to the control. Also, none of the LAB strains showed good adhesion to Caco-2/TC7 cells, with a maximum adherence of Lactobacillus plantarum CECT 749.
Conclusões:Although the selected LAB showed an excellent potential for OTA degradation in vitro, no reduction of OTA was observed in the simulated digestion system.