Polyphasic identification, cyp51A-RFLP differentiation, and biomass production of Aspergillus section Flavi isolates from cereal grains collected in Tulcán, Ecuador

Accurate identification of species within Aspergillus section Flavi is essential due to their relevance to food safety and industrial biotechnology, and to the taxonomic complexity arising from morphological and genetic similarities among closely related species such as Aspergillus flavus and Aspergillus oryzae . In this study, a polyphasic approach was applied to characterize fungal isolates obtained from rice, oat, and wheat grains collected in Tulcán, Ecuador. Identification included macroscopic and microscopic characterization, amplification of the ITS region, phylogenetic analysis, and molecular differentiation by PCR-RFLP of the cyp 51A gene using the restriction enzyme HincII. Molecular results allowed the classification of isolates M5A2, M5A3, M5A5, M10A1, M10A2, and M10A3 as Aspergillus tamarii . The isolate M6A5 was identified as Aspergillus oryzae , as confirmed by the restriction pattern of the cyp 51A gene, demonstrating the usefulness of the polyphasic strategy for resolving closely related species within section Flavi . None of the isolates showed detectable aflatoxin production on coconut agar, suggesting their potential suitability for biotechnological applications. In a preliminary evaluation, biomass production exceeded 15 g/L in isolates M10A2 and M6A5, indicating high mycelial growth capacity. These results indicate that the native mycobiota associated with cereal grains represents a valuable microbial resource with potential for future biotechnological valorization.