Morphomolecular identification of two new isolates of Aspergillus niger, PP373715 (ITS) and PP596863 (BenA), in agroforestry systems in Buenaventura, Colombia

Abstract

A reliable diagnosis of Aspergillus species requires the use of an integrative taxonomy (macro, microscopic- and molecular-based analysis). In this research, the population of Aspergillus in agroforestry systems in Buenaventura (Colombia) was examined. The CYA and YES colonies had powdery surfaces, white areas and black pigmentation. The colony produces a colorless exudate, sclerotia are absent, and the reverse pigmentation is pale yellow. The radial folds are irregular. The micromorphology of the isolates revealed the presence of radiate conidial heads. Biseriate conidiophores. Hyaline, thick-walled, smooth stipes measuring 1482.59 ± 52.45 (759.97-1946.12) × 6.36 ± 1.25 (5.24–9.37) µm were used. Vesicles globose to subglobose, 45.25 ± 3.98 (38.51–56.37) × 38.54 ± 4.58 (33.54–52.83) µm. Metulae 11.42 ± 1.24 (9.83–13.59) x 2.50 ± 0.24 (2.29–2.74) µm, covering 100% of the head. Phialides ampulliform, 12.28 ± 0.84 (9.36–11.59) x 2.36 ± 0.21 (2.17–2.64) µm. Conidia globose, rough, 2.67 ± 0.43 (2.40–2.97) × 2.43 ± 0.35 (2.24–2.89) µm. Two DNA sequences were obtained from the study: one for the internal transcribed spacer (ITS) segment (PP373715) and the other for the β-tubulin gene (PP596863). These sequences matched those of A. niger. ITS region and β-tubulin gene analyses revealed that the isolates were Aspergillus niger. This study presents the first sequences of this fungus in agroforestry systems in the study area (Buenaventura, Colombia). For species identification in the genus Aspergillus, the ITS region and the presence of the BenA gene are currently mandatory. The detection of A. niger in local agroforestry systems (AFSs) could enhance soil and ecosystem quality while reducing the reliance on pesticides. The secondary metabolites produced by this fungus could be employed in the agricultural industry to identify promising native species in the Colombian Pacific.