title: Molecular characterization of black Aspergillus species from onion and their potential for ochratoxin A and fumonisin B2 production.
abstract: Onion bulbs can become contaminated with various molds during the storage period, the most important causal agents being black aspergilli (Aspergillus section Nigri). Taxonomic studies have revealed that this group of Aspergillus contains many species that cannot be reliably identified using standard morphological methods. Therefore, it is necessary to define the fungus causing this problem in the onion exactly, especially since some species assigned to section Nigri are well known as ochratoxin and/or fumonisin producers. Sixty fungal isolates belonging to 10 fungal genera were isolated from 40 onion samples originated from the Taif region in Saudi Arabia. Black aspergilli were detected in 37 onion samples. Using primer pairs (awaspec and Cmd6) designed based on partial calmodulin gene sequence data, 37 isolates were identified as A. welwitschiae. The ochratoxin A and fumonisin B2 contents of the onion samples were examined. No ochratoxins were detected in the collected samples, while fumonisin B2 was detected in 37.5% of the onion samples. Eighteen of 37 isolates of Aspergillus welwitschiae were recognized as potential producers for fumonisin B2. Multiplex polymerase chain reactions designed to detect biosynthetic genes of fumonisins confirmed these results.
authors.affiliation: 1 Biological Sciences Department, Faculty of Science, Taif University , Taif, Saudi Arabia .
authors.forename: Youssuf
authors.initials: Y
authors.lastname: Gherbawy
authors.forename: Hesham
authors.initials: H
authors.lastname: Elhariry
authors.forename: Sándor
authors.initials: S
authors.lastname: Kocsubé
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Bahobial
authors.forename: Bahig El
authors.initials: BE
authors.lastname: Deeb
authors.forename: Abdulla
authors.initials: A
authors.lastname: Altalhi
authors.forename: János
authors.initials: J
authors.lastname: Varga
authors.forename: Csaba
authors.initials: C
authors.lastname: Vágvölgyi
mesh_terms: D001234:Aspergillus niger / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004271:DNA, Fungal / Q000235:genetics; D005506:Food Contamination; D005516:Food Microbiology; D037341:Fumonisins / Q000737:chemistry*; D005656:Fungal Proteins / Q000235:genetics*; D014644:Genetic Variation; D009793:Ochratoxins / Q000737:chemistry*; D019697:Onions / Q000382:microbiology*; D012529:Saudi Arabia; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal; D037341:Fumonisins; D005656:Fungal Proteins; D009793:Ochratoxins; C056934:fumonisin B2; C025589:ochratoxin A