Gluconobacter oxydans – potential biological agent for binding or biotransformation of mycotoxins

Abstract

The potential application of viable and heat-treated cells ofGluconobacter oxydans for binding or degradation of aflatoxin B1 (AFB1), citrinin (CIT), ochratoxin A (OTA) and patulin (PAT) in liquid matrix was investigated. Experiments were conducted using uncontaminated and toxin-containing YPM (yeast-peptone-mannitol) medium and inoculated with a bacterium suspension of either viable or heat-treated cells (108 cfu/ml) and incubated at 28 °C for 24 h. The unbound AFB1 and OTA were quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS), whereas CIT and PAT were quantified by high performance liquid chromatography (HPLC). Obtained results suggest thatG. oxydans is able to bind various mycotoxins by 26 to 94%. Viable cells showed the best binding ability towards OTA and PAT (80.8 and 93.8%, respectively), while heat-treated cells bound less than 50% of tested mycotoxins. Fourier transform infrared spectroscopy (FTIR) showed that partial removal of mycotoxins involves physical binding of the toxin to the proteins and polysaccharides constituting the bacterial cell wall. Since mycotoxins contain numerous functional groups that multiply the IR spectra upon binding to bacteria, the precision of FTIR monitoring of bacteria-mycotoxin interactions is limited.