Impact of Kluyveromyces marxianus VM004 culture conditions on the cell wall structure and its influence on aflatoxin B1 binding

The aim of this study was to determine the impact of Kluyveromyces marxianus VM004 culture conditions on the cell wall (CW) structure and its influence on aflatoxin B₁ binding. The yeast was inoculated into two types of culture media: yeast extract-peptone-dextrose (YPD) broth and dried distiller's grains with solubles (DDG). The CW was extracted from the biomass produced in these media. AFB₁ (150ng/ml) adsorption tests using the biomass (1×10⁷cells/ml) and the CW (0.001g) were performed at pH 2 and pH 8. Transmission electron microscopy (TEM) evaluated the CW thickness, and infrared spectroscopy (IR) determined the CW composition. Biomass production in YPD was higher than that in DDG. Cell diameter (μm) and CW thickness (μm) increased in the DDG medium. The CW percentage obtained in DDG was higher than that in YPD. The absorbance of carbohydrates by IR was higher in YPD. pH influenced AFB₁ adsorption, which was lower at pH 8. The proportion of β-glucan and chitin present in CW was higher in the YPD medium. The IR method allowed to study the CW carbohydrate variation under the influence of these carbon sources. In conclusion, the culture media composition influenced the β-glucan and chitin composition and consequently, AFB₁ adsorption.