title: Degradation of ochratoxin A by Bacillus amyloliquefaciens ASAG1.
abstract: Ochratoxin A (OTA) is widely found in food and feed products as a mycotoxin contaminant. It is produced by Penicillium species and several Aspergillus species. The identification OTA detoxification microorganisms is believed to be the best approach for decontamination. In this study, we isolated ASAG1, a bacterium with the ability to degrade OTA effectively, from grain depot-stored maize. A 16S rDNA sequencing approach was used to identify this strain as Bacillus amyloliquefaciens ASAG1. The degradation of OTA was detected in both medium and cell-free extracts after incubation with a culture of B. amyloliquefaciens ASAG1 cells. Subsequently, a hydrolysed enzyme (carboxypeptidase) related to the enzymatic conversion of OTA was cloned from the B. amyloliquefaciens ASAG1 genome. Using the Escherichia coli Expression System, we successfully expressed and purified this carboxypeptidase. When this enzyme was incubated with the engineered recombinant E. coli cells, the concentration of OTA was dramatically degraded. Our data therefore indicate that the carboxypeptidase produced by B. amyloliquefaciens ASAG1 is likely responsible for the biodegradation of OTA.
authors.affiliation: a Cereals and Oils Microbiology Research Group , Academy of State Administration of Grain , Beijing , China.
authors.forename: Xiaojiao
authors.initials: X
authors.lastname: Chang
authors.forename: Zidan
authors.initials: Z
authors.lastname: Wu
authors.forename: Songling
authors.initials: S
authors.lastname: Wu
authors.forename: Yanshi
authors.initials: Y
authors.lastname: Dai
authors.forename: Changpo
authors.initials: C
authors.lastname: Sun
mesh_terms: D001230:Aspergillus; D001407:Bacillus / Q000145:classification / Q000201:enzymology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D003666:Decontamination; D002523:Edible Grain / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D009793:Ochratoxins / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D003313:Zea mays / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009793:Ochratoxins; D012336:RNA, Ribosomal, 16S; C025589:ochratoxin A; D002268:Carboxypeptidases
keywords: Bacillus amyloliquefaciens; biocontrol; carboxypeptidase; ochratoxin A