OCHRATOXIN PRODUCTION DETECTION BY THIN LAYER CHROMATOGRAPHY OF ASPERGILLUS SECTION NIGRI STRAINS ISOLATED FROM COMPOSED YERBA MATÉ.

CASTRILLO MARIA LORENA , JERKE GLADIS Y HORIANSKI MARTA AURELIA

Ciudad de Santa Fe, Santa Fe, Argentina.

Workshop; 2nd Latin Americam Pesticide Residue Workshop (LAPRW2009); 2009

Universidad Nacional del Litoral, Facultad de Ingeniería Química y el Laboratorio Central; y co-organizada con otras universidades y centros de investigación de Latín America.

Micotoxins are secundary metabolism products of several mould species, characterized by both a diversity of chemicals structures and the biological activities, which cause harmful biological alterations for humans and animals health. Ochratoxin A (OTA) is an teratogenic, immunosuppressor, nefrotoxic and carcinogenic mycotoxin produced by the genus Aspergillus and Penicillium. The chlorine molecule in its structure is responsable for the toxic character and it’s termostability and water soluble properties. The disease appears after a cronic ingestion of foods or drinks containing very small concentrations of the toxin. Recent studies demostrated that Aspergillus belonging to the nigri section are important producers of this toxin and are a part of micota found in diverse food. The objective of the present work was to determine ochratoxin A production by Aspergillus species from the nigri’s section isolated from composed yerba maté by thin layer chromatography. Aspergillus strains were isolated from 41 samples of composed yerba maté obtained from commerces of Posadas, Misiones, Argentina. Were worked with 43 Aspergillus section nigri strains and a pattern strain producing Ochratoxin A (A. Carbonarius JFPE 1546). The strains were clasified using Klich Maren, 2002 codes, characterizing 17 A. japonicus var japonicus strains, 12 A. japonicus var aculeatus strains, 7 A. niger var niger strains, 5 A. foetidus strains, 1 A. carbonarius strain y 1 A. niger var awamori strain. The strains were cultivated in Czapeck Yeast Extract Agar (CYA) and incubated in darkness at 25ºC for 7 days. Entire culture medium extraction with chloroform was perform by agitation at 250 rpm for 1 hour and 30 minutes. The extract was filtered, evaporated in a stove at 50ºC and resuspended in 1 ml of chloroform:ether:acetic acid 17:3:1. 10 µl of the samples, pattern and standard strains were deposited in a Silica Gel 60 chromatographic plate. Chloroform:ether:acetic acid 17:3:1 was used as running solvent. OTA was identified under UV light at 366 nm as a bluish green fluorescent stain with the same mobility as the OTA standard. As confirmation, the stains were exposed to ammoniac vapors since the bluish green fluorescence turns to a brilliant blue in the presence of OTA. From the 43 strains we studied only one strain of A. japonicus var aculeatus showed ochratoxin A production in vitro at level detection of employed methodology. The obtained results showed an ocratoxicogenic strain incidence of 8 % of the Aspergillus japonicus var aculeatus and 2 % of all of the analized strains. In previous studies we have found that the most frequent contaminant mould in tradicional  and composed yerba maté belongs to Aspergillus section nigri. Taking into account that black aspergillus are considered to be a source for OTA in tropical and subtropical climates and that OTA traces have been found in numerous individual serum without being able to specify the origin, at present, we are focused on the toxin analysis in samples of composed yerba maté.