Isolation and identification of a Cytobacillus oceanisediminis strain with ochratoxin A detoxification ability

Ochratoxin A (OTA) is a polyketide mycotoxin produced by several Aspergillus and Penicillium species that is of great concern as a contaminant in agricultural products. In this study, the bacterial strain CO29 with high OTAdetoxification ability was isolated from vineyards and was identified as Cytobacillus oceanisediminis based on morphological and physiological characteristics, combined with 16S rRNA gene sequencing and phylogenetic analysis. The removal of OTA by CO29 was partly attributed to physical absorption, but the main mechanism of OTA removal was degradation. The degradation activity was completely removed by boiling, and could be significantly reduced by proteinase K treatment, but was only partially inhibited by the metal chelator EDTA. Zn2+ significantly improved the degradation of OTA, while Ca2+ and Mg2+ significantly inhibited the degradation. In addition, organic solvents inhibited OTA degradation in a dose-dependent manner. Thus, the mechanism of degradation by CO29 cell lysates was deduced as being enzymatic. Two OTA degradation intermediates were observed, one of which was identified as OT alpha. The time-profiles of OTA degradation by cell lysates showed an increase of OT alpha corresponding to the decrease of OTA. To our best knowledge, this is the first report of a Cytobacillus oceanisediminis strain with the ability to detoxify OTA, with potential applications in the bioremediation of contaminated soils.

Automated summary

In this study, a bacterial strain CO29 with high OTA detoxification ability was isolated from vineyards and identified as Cytobacillus oceanisediminis. The removal of OTA by CO29 was mainly attributed to degradation, which was completely removed by boiling and could be significantly reduced by proteinase K treatment. OTA degradation was significantly improved by Zn2+, while inhibited by Ca2+ and Mg2+. Organic solvents inhibited OTA degradation in a dose-dependent manner. Two OTA degradation intermediates were observed, one of which was identified as OT alpha. This is the first report of Cytobacillus oceanisediminis strain with the ability to detoxify OTA.