Study of Spanish Grape Mycobiota and Ochratoxin A Production by Isolates of Aspergillus tubingensis and Other Members of Aspergillus Section Nigri

Abstract

The native mycobiota of five grape varieties grown in Spain has been studied. Four (Bobal, Tempranillo, Garnacha, and Monastrell) were red varieties and one (Moscatel) was white. The main fungal genera isolated were Alternaria, Cladosporium, and Aspergillus. The isolation frequency of Aspergillus spp. section Nigri in contaminated samples was 82%. Ochratoxin A (OTA) production was assessed using yeast extract-sucrose broth supplemented with 5% bee pollen. Cultures of 205 isolates from this section showed that 74.2% of Aspergillus carbonarius and 14.3% of Aspergillus tubingensis isolates produced OTA at levels ranging from 1.2 to 3,530 ng/ml and from 46.4 to 111.5 ng/ml, respectively. No Aspergillus niger isolate had the ability to produce this toxin under the conditions assayed. Identification of the A. niger aggregate isolates was based on PCR amplification of 5.8S rRNA genes and its two intergenic spacers, internal transcribed spacer 1 (ITS1) and ITS2, followed by digestion with restriction endonuclease RsaI of the PCR products. The restriction patterns were compared with those from strains of A. niger CECT 2807 and A. tubingensis CECT 20393, held at the Spanish Collection of Type Cultures. DNA sequencing of the ITS1-5.8S rRNA gene-ITS2 region of the OTA-producing isolates of A. tubingensis matched 99 to 100% with the nucleotide sequence of strain A. tubingensis CBS 643.92. OTA determination was accomplished by liquid chromatography with fluorescence detection. OTA confirmation was carried out by liquid chromatography coupled to ion trap mass spectrometry. The results showed that there are significant differences with regard to the isolation frequency of ochratoxinogenic fungi in the different grape varieties. These differences were uncorrelated to berry color. The ability of A. tubingensis to produce OTA and the influence of grape variety on the occurrence of OTA-producing fungi in grapes are described in this report for the first time.

Endophytic fungi from Vitis labrusca L. ‘Niagara Rosada’) and its potential for the biological control of Fusarium oxysporum

“…These fungi have also been isolated from various plants from tropical and subtropical regions, including Saccharum sp (Mendes and Azevedo, 2007), Theobroma cacao (Rubini et al, 2005;Hamada, 2006), Musa (Cao et al, 2003), Arachis (Suryanarayanan and Murali, 2006), Euterpe (Rodrigues, 1994), and Citrus spp (Araújo et al, 2001;Durán et al, 2005). Several of the species we isolated have also been found as endophytes of V. vinifera (Medina et al, 2005;Martini et al, 2009) and V. labrusca (Lima, 2010). Other isolates, such as those belonging to the phylum Basidiomycota, including the species B. adusta, F. flavus, P. sordida, P. nebrodensis, and T. epimiltinus, were dominant and had not, to date, been isolated as endophytes from tropical plants.…”

“…These studies are usually concerned with the characterization of the endophytic communities (Mostert et al, 2000;Medina et al, 2005;Martini et al, 2009). Characterization of the endophytic fungal community of Vitis labrusca has been conducted by Brum (2006) and Lima (2010).…”

Incidence of ochratoxin A in rice and dried fruits from Rabat and Salé area, Morocco

“…Other black aspergilli including the A. niger aggregate and A. aculeatus have also been found to produce OTA on grapes (Battilani et al, 2003). Recently, OTA production in A. tubingensis isolates originating from grapes was observed by Medina et al (2005).…”

Determination of mycotoxin profiles characteristic ofAlternariastrains isolated from Malbec grapes

“…The incidence of Alternaria in grapes has been reported in different percentages with respect to total mycobiota: 5-23% in USA, 25% in Italy, 80% in Argentina; 3-18%, 24%, 17% in different studies in Portugal, 75%, 3-58%, 13% in Spain, and A. alternata and A. tenuissima were reported in 16-19% in Slovakia [7,8,13,15,24,25,[35][36][37][38][39][40][41][42].…”