Increased Cd 2+ biosorption capability of Aspergillus nidulans elicited by crpA deletion.

The P-type ATPase CrpA is an important Cu ²⁺ /Cd ²⁺ pump in the Aspergilli, significantly contributing to the heavy metal stress tolerance of these ascomycetous fungi. As expected, the deletion of crpA resulted in Cu ²⁺ /Cd ²⁺ -sensitive phenotypes in Aspergillus nidulans on stress agar plates inoculated with conidia. Nevertheless, paradoxical growth stimulations were observed with the ΔcrpA strain in both standard Cu ²⁺ stress agar plate experiments and cellophane colony harvest (CCH) cultures, when exposed to Cd ²⁺ . These observations reflect efficient compensatory mechanisms for the loss of CrpA operating under these experimental conditions. It is remarkable that the ΔcrpA strain showed a 2.7 times higher Cd biosorption capacity in CCH cultures, which may facilitate the development of new, fungal biomass-based bioremediation technologies to extract harmful Cd ²⁺ ions from the environment. The nullification of crpA also significantly changed the spatial distribution of Cu and Cd in CCH cultures, as demonstrated by the combined particle-induced X-ray emission and scanning transmission ion microscopy technique. Most important, the centers of gravity for Cu and Cd accumulations of the ΔcrpA colonies shifted toward the older regions as compared with wild-type surface cultures.
(© 2020 The Authors. Journal of Basic Microbiology published by Wiley-VCH Verlag GmbH & Co. KGaA.)