Cadmium-Resistant Fungi from Cocoa Crops: Isolation, Morphological Identification and Tolerance Assessment

Abstract

The objective of the present study is to isolate and evaluate native fungi of cocoa soils that possess tolerance to cadmium in order to apply them in cadmium bioremediation in cocoa plantations. The soil samples were collected from the cocoa areas of Junín, Pucallpa and Mazamari, Peru. The fungi were isolated from the colony on potato dextrose agar (PDA) and recognized by their appearance. To exclude out non-resistant or poorly resistant strains, all of the identified strains were cultured on PDA agar with 87.64 ppm of cadmium. Positive strains were identified by their macroscopic and microscopic morphology. The diameter of the colony established on PDA with 87.64, 175.29, and 350.59 ppm of cadmium was measured to determine cadmium tolerance. A total of 100 fungal strains were isolated, with 24 showing tolerance to 87.64 ppm, 21 to 175.29 ppm, and 16 to 350.59 ppm. The fungi with the highest tolerance were J2E2 (Acremonium sp.), MP4H1 (Curvularia sp.), HK6 (Not Described, ND) and JH3 (Fusarium sp.) respectively. Likewise, the strains with the best tolerance indices were HK6 (ND), H2 (Penicillium sp.), AP3H4 (ND) and J2E2 (Acremonium sp.). The findings suggest that native fungi isolated from cocoa soils are tolerant of high cadmium concentrations, suggesting that they could be employed as bioremediators in cocoa farms or other biotechnological processes.