Aspergillus niger isolated from stored peanuts seeds in Argentin. Classic and molecular characterization.

MAGNOLI C.E.,; FERNÁNDEZ- JURI M.G.; DALCERO A.M.

Florianópolis, Brasil

Congreso; V CLAM & ENM´2006, V Congreso Latino- Americano Micotoxicologia.; 2006

Peanut (Arachis hypogaea L) is an important crop in Argentina, with Córdoba province accounting for approximately 98% of total peanut production. Most of the production is exported to various regions of the world and the rest is destined to the internal market. This substrate is often invaded before harvest by Aspergillus section Nigri species. A. carbonarius and A. niger are the main ochratoxin A producing in several commodities. In this work Aspergillus niger species were identified by classic methodology and AFLP to assess the genetic relation between A. niger strains isolated from peanuts. A total of fifty peanut samples were collected from a storing plant located in the south of Córdoba province, Argentina. The species were isolated by direct inoculation method with superficial disinfection of fruits. The culture medium was Dicloran Glicerol 18% (DG18). A total of 134 strains were identified by classic taxonomy (Klich, 2002) and AFLP (Vos et al. 1995, Zeller et al. 2000). For molecular characterization, fungal DNA extraction was done with cetyltrimethylammonium bromide (CTAB) method according to Murray and Thompson (1980), as modified by Kérenyi et al. (1999). AFLPs reactions were performed as described Vos et al. (1995), as modified by Zeller et al. (2000). The selective primers combinations analysis produced a complex fingerprinting pattern. Fifty two polymorphic AFLP bands (85.24%) were identified among a total of 61 bands generated with the best combination of primers (EcoRI + TG y MseI + CG). The average of similarity among the 134 strains was 75% (range: 44-98%). These results indicate that these strains correspond at the same specie. The members of section Nigri are difficult to differentiate by the superposition of morphologically characters. The AFLP technical could be a useful tool to evaluate the genetic differences between these species.