Abstract
Ochratoxin A (OTA) is a mycotoxin with a main nephrotoxic activity contaminating several foodstuffs. In the present report, five soil samples collected from OTA-contaminated vineyards were screened to isolate microorganisms able to biodegrade OTA. When cultivated in OTA-supplemented medium, OTA was converted in OTα by 225 bacterial isolates. To reveal clonal relationships between isolates, molecular typing by using an automated rep-PCR system was carried out, thus showing the presence of 27 different strains (rep-PCR profiles). The 16S-rRNA gene sequence analysis of an isolate representative of each rep-PCR profiles indicated that they belonged to five bacterial genera, namely Pseudomonas, Leclercia, Pantoea, Enterobacter, and Acinetobacter. However, further evaluation of OTA-degrading activity by the 27 strains revealed that only Acinetobacter calcoaceticus strain 396.1 and Acinetobacter sp. strain neg1, consistently conserved the above property; their further characterization showed that they were able to convert 82% and 91% OTA into OTα in six days at 24 °C, respectively. The presence of OTα, as the unique OTA-degradation product was confirmed by LC-HRMS. This is the first report on OTA biodegradation by bacterial strains isolated from agricultural soils and carried out under aerobic conditions and moderate temperatures. These microorganisms might be used to detoxify OTA-contaminated feed and could be a new source of gene(s) for the development of a novel enzymatic detoxification system.
Highlights
Mycotoxins are natural contaminants in foodstuffs that, according to the Food and AgriculturalOrganization (FAO), contaminate more than 25% of the world’s commodities [1]
An aliquot of each one of the three soil suspensions with ochratoxin A (OTA)-degrading ability was used to inoculate Medium Peptone (MMP) and Potatto Dextrose Broth (PDB) supplemented with 10 μg/mL of OTA and a given antibiotic or an antifungal agent
Database searches with these sequences showed identities >99% with type strain sequences available in database, leading to the assignment of the following bacterial species: Acinetobacter calcoaceticus, Pseudomonas taiwanensis, Pseudomonas reinekei, Pseudomonas koreensis, Leclercia adecarboxylata, Pantoea agglomenans, Enterobacter aerogenes, and Enterobacter xiangfangensis (Table 1)
Summary
Mycotoxins are natural contaminants in foodstuffs that, according to the Food and Agricultural. Bacterial strains of soil origin belonging to Nocardioides and Devosia genera were characterized for their capacity to degrade DON to 3-epi-deoxynivalenol [36], whereas Islam et al [35] isolated from agricultural soils bacterial populations able to biodegrade DON under aerobic conditions and moderate temperatures via a de-epoxydation mechanism. With this regard, in our knowledge, this is the first study aimed to evaluate degradation of ochratoxin A in soil samples from vineyards contaminated by high levels of OTA in order to isolate new microorganisms with OTA-degrading ability
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