Aspergillus westerdijkiae polyketide synthase gene “aoks1” is involved in the biosynthesis of ochratoxin A

Bacha, Nafees; Atoui, Ali; Mathieu, Florence; Liboz, Thierry; Lebrihi, Ahmed

doi:10.1016/j.fgb.2008.09.015

Cited by 59 publications

(54 citation statements)

References 47 publications

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“…Growth rates at 37°C can be a useful feature to differentiate between these species without sequencing (3). Aspergillus westerdijkiae is commonly found in environmental samples (30) and as a food (31) and indoor contaminant (31)(32)(33)(34)(35). In the clinical setting, A. westerdijkiae has been linked to superficial infections (12) and isolated from sputum of immunocompromised patients in Tunisia (19).…”

Section: Discussionmentioning

confidence: 99%

Multilocus Phylogeny and Antifungal Susceptibility of Aspergillus Section Circumdati from Clinical Samples and Description of A. pseudosclerotiorum sp. nov

et al. 2017

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A multilocus phylogenetic study was carried out to assess species identity of a set of 34 clinical isolates from Aspergillus section Circumdati from the United States and to determine their in vitro antifungal susceptibility against eight antifungal drugs. The genetic markers used were the internal transcribed spacer (ITS) region, and fragments of the beta-tubulin (BenA), calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) genes. The drugs tested were amphotericin B, itraconazole, posaconazole, voriconazole, anidulafungin, caspofungin, micafungin, and terbinafine. The most common species sampled was A. westerdijkiae (29.4%), followed by a novel species, which was described here as A. pseudosclerotiorum (23.5%). Other species identified were A. sclerotiorum (17.6%), A. ochraceus (8.8%), A. subramanianii (8.8%), and A. insulicola and A. ochraceopetaliformis, with two isolates (5.9%) of each. The drugs that showed the most potent activity were caspofungin, micafungin, and terbinafine, while amphotericin B showed the least activity.KEYWORDS Aspergillus, Circumdati section, clinical isolates, molecular identification, phenotypic identification S ection Circumdati includes aspergilli with biseriate conidial heads in shades of yellow to ochre, with mostly globose vesicles, and sclerotia variable in shape and color (1-3). It contains 26 species (3), with A. ochraceus being the best known and described as an important producer of many extrolites, including the mycotoxin ochratoxin A (3-5). This metabolite has nephrotoxic, immunosuppressive, teratogenic, and carcinogenic properties (6, 7) and is commonly found in coffee, rice, beverages, and other contaminated foodstuffs (3,8). Several species in this section have been involved in different types of infections, such as onychomycosis, caused by A. insulicola, A. melleus, A. ochraceopetaliformis, A. persii, A. sclerotiorum, and A. westerdijkiae (9-14); otomycosis, caused by A. sclerotiorum (15); skin infection, caused by A. westerdijkiae (12); and pulmonary aspergillosis and osteomyelitis, caused by A. ochraceus (16,17). Moreover, A. ochraceus, A. sclerotiorum, and A. westerdijkiae have been repetitively isolated from clinical specimens of immunocompromised patients, although in such cases their pathogenic role is uncertain (18)(19)(20)(21)(22).There are few data on the in vitro antifungal susceptibility of species within section Circumdati. The azoles, especially itraconazole, appear to have good activity against A.

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Section: Discussionmentioning

confidence: 99%

Multilocus Phylogeny and Antifungal Susceptibility of Aspergillus Section Circumdati from Clinical Samples and Description of A. pseudosclerotiorum sp. nov

et al. 2017

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“…The OTA biosynthetic pathway has not yet been fully biochemically or genetically elucidated, despite the cloning of OTA polyketide synthase genes from several fungal species including A. ochraceus (O'Callaghanet al 2003), Aspergillus westerdijkiae (Bacha et al 2009) and P. nordicum (Karolewiez and Geisen 2005). OTA is a hybrid molecule composed of a type 1 polyketide dihydroisocoumarin moiety, linked via an amide bond to the amino acid, phenylalanine.…”

Section: Discussionmentioning

confidence: 99%

Isolation, characterization and evaluation of significant mycoflora and mycotoxins in pig feed from Serbian farms

Milićević

Nikšić

Baltić

et al. 2010

World J Microbiol Biotechnol

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This paper provides a brief review of approaches for the early detection and prevention strategies which have been employed in Serbia for the control of ochratoxogenic fungi and its metabolites in feed in the context of a hazard analysis critical control point (HACCP) framework. During a mycological analysis of complete feedmixes intended for fattening swine (n = 18), a total of six genera and 14 species of moulds were identified. Penicillium was present in considerably more samples than any other genus (94.4%), followed by the genera Fusarium (55.5%) and Paecilomyces (44.4%). Other fungi from the genera Aspergillus (22%), Mucor (11.1%) and Alternaria (5.5%) were represented in a smaller amount. Total fungal counts ranged from 10 5 to 40 9 10 5 c.f.u./g. The mycotoxins deoxynivalenol, ochratoxin A and zearalenone were detected, while aflatoxins were not present. Deoxynivalenol was detected in 10 samples in the concentration range 0.25-2.5 mg/kg. Ochratoxin A and zaralenone were detected in nine and eight samples, respectively, in the concentration range 0.057-0.27 and 0.2-5.0 mg/kg, respectively. Isolates identified as Aspergillus and Penicillium species were subjected to molecular characterization for the presence of genes responsible for the synthesis of OTA (polyketide synthase gene-PKS) using polymerase chain reaction (PCR) applied to a set of 18 isolates. The sequences of PCR reaction products in three samples were compared with nucleotide sequences of genes for polyketide synthase (PKS) from Penicillium species and it was found that the samples possessed the PKS sequence. These findings indicate that there may be a risk of animal exposure to mycotoxins through the consumption of mouldy infected feeds.

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“…The orthologs of these genes have also been identified for the closely related species P. verrucosum, but have not yet been identified in the major OTA-producing aspergilli. So far, in Aspergillus spp., specifically in A. ochraceus (41) and in A. westerdijkiae (6), only the pks genes involved in the initial steps of the pathway have been characterized. In A. carbonarius, an economically and scientifically interesting species due to its predominant role in the contamination of grapes, the presence of different pks genes was investigated (5).…”

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confidence: 99%

New Insight into the Ochratoxin A Biosynthetic Pathway through Deletion of a Nonribosomal Peptide Synthetase Gene in Aspergillus carbonarius

Gallo

Bruno

Solfrizzo

et al. 2012

Appl Environ Microbiol

102

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bOchratoxin A (OTA), a mycotoxin produced by Aspergillus and Penicillium species, is composed of a dihydroisocoumarin ring linked to phenylalanine, and its biosynthetic pathway has not yet been completely elucidated. Most of the knowledge regarding the genetic and enzymatic aspects of OTA biosynthesis has been elucidated in Penicillium species. In Aspergillus species, only pks genes involved in the initial steps of the pathway have been partially characterized. In our study, the inactivation of a gene encoding a nonribosomal peptide synthetase (NRPS) in OTA-producing A. carbonarius ITEM 5010 has eliminated the ability of this fungus to produce OTA. This is the first report on the involvement of an nrps gene product in OTA biosynthetic pathway in an Aspergillus species. The absence of OTA and ochratoxin ␣, the isocoumaric derivative of OTA, and the concomitant increase of ochratoxin ␤, the dechloro analog of ochratoxin ␣, were observed in the liquid culture of transformed strain. The data provide the first evidence that the enzymatic step adding phenylalanine to polyketide dihydroisocoumarin precedes the chlorination step to form OTA in A. carbonarius and that ochratoxin ␣ is a product of hydrolysis of OTA, giving an interesting new insight into the biosynthetic pathway of the toxin.

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Aspergillus westerdijkiae polyketide synthase gene “aoks1” is involved in the biosynthesis of ochratoxin A

Cited by 59 publications

References 47 publications

Multilocus Phylogeny and Antifungal Susceptibility of Aspergillus Section Circumdati from Clinical Samples and Description of A. pseudosclerotiorum sp. nov

Multilocus Phylogeny and Antifungal Susceptibility of Aspergillus Section Circumdati from Clinical Samples and Description of A. pseudosclerotiorum sp. nov

Isolation, characterization and evaluation of significant mycoflora and mycotoxins in pig feed from Serbian farms

New Insight into the Ochratoxin A Biosynthetic Pathway through Deletion of a Nonribosomal Peptide Synthetase Gene in Aspergillus carbonarius

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