Biodegradation of Ochratoxin A by Bacterial Strains Isolated from Vineyard Soils

Abstract: Ochratoxin A (OTA) is a mycotoxin with a main nephrotoxic activity contaminatingseveral foodstuffs. In the present report, five soil samples collected from OTA-contaminatedvineyards were screened to isolate microorganisms able to biodegrade OTA. When cultivated inOTA-supplemented medium, OTA was converted in OTalpha by 225 bacterial isolates. To revealclonal relationships between isolates, molecular typing by using an automated rep-PCR systemwas carried out, thus showing the presence of 27 different strains (rep-PCR profiles). The16S-rRNA gene sequence analysis of an isolate representative of each rep-PCR profiles indicatedthat they belonged to five bacterial genera, namely Pseudomonas, Leclercia, Pantoea, Enterobacter, andAcinetobacter. However, further evaluation of OTA-degrading activity by the 27 strains revealedthat only Acinetobacter calcoaceticus strain 396.1 and Acinetobacter sp. strain neg1, consistentlyconserved the above property; their further characterization showed that they were able to convert82% and 91% OTA into OTalpha in six days at 24 °C, respectively. The presence of OTalpha, asthe unique OTA-degradation product was confirmed by LC-HRMS. This is the first report onOTA biodegradation by bacterial strains isolated from agricultural soils and carried out underaerobic conditions and moderate temperatures. These microorganisms might be used to detoxifyOTA-contaminated feed and could be a new source of gene(s) for the development of a novelenzymatic detoxification system.