title: Mechanisms involved in reduction of ochratoxin A produced by Aspergillus westerdijkiae using Debaryomyces hansenii CYC 1244.
abstract: Aspergillus westerdijkiae is one of the most relevant ochratoxin A (OTA) producing species within the Section Circumdati contaminating a number of agroproducts. The yeast Debaryomyces hansenii CYC 1244 was previously reported to be able to reduce growth and extracellular OTA produced by A. westerdijkiae. In this work, we examined several mechanisms possibly involved in this OTA reduction in in vitro experiments. OTA biosynthesis was evaluated by quantitation of expression levels of pks (polyketide synthase) and p450-B03 (cytochrome p450 monooxygenase) genes using newly developed and specific real time RT-PCR protocols. Both genes showed significant lower levels in presence of D. hansenii CYC 1244 suggesting an effect on regulation of OTA biosynthesis at transcriptional level. High levels of removal of extracellular OTA were observed by adsorption to yeast cell walls, particularly at low pH (98% at pH 3). On the contrary, no evidences were obtained of absorption of OTA into yeast cells or the production of constitutively expressed enzymes that degrade OTA by D. hansenii CYC 1244. These results described the potential of this yeast strain as a safe and efficient biocontrol agent to decrease OTA in A. westerdijkiae and two important mechanisms involved which may permit its application at different points of the food chain.
authors: Department of Microbiology III, Faculty of Biology, University Complutense of Madrid, José Antonio Novais 2, 28040-Madrid, Spain. jgilsern@bio.ucm.es
authors: Jéssica
authors: J
authors: Gil-Serna
authors: Belén
authors: B
authors: Patiño
authors: Laura
authors: L
authors: Cortés
authors: María Teresa
authors: MT
authors: González-Jaén
authors: Covadonga
authors: C
authors: Vázquez
mesh_terms: D000327:Adsorption; D001230:Aspergillus / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D061046:Biological Control Agents; D002473:Cell Wall / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006863:Hydrogen-Ion Concentration; D009793:Ochratoxins / Q000096:biosynthesis*; D048630:Polyketide Synthases / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D004718:Saccharomycetales / Q000502:physiology*
chemical_list: D061046:Biological Control Agents; D009793:Ochratoxins; C025589:ochratoxin A; D048630:Polyketide Synthases