Fungus Aspergillus niger Processes Exogenous Zinc Nanoparticles into a Biogenic Oxalate Mineral

Abstract

Zinc oxide nanoparticles (ZnO NPs) belong to the most widely used nanoparticles in both commercial products and industrial applications. Hence, they are frequently released into the environment. Soil fungi can affect the mobilization of zinc from ZnO NPs in soils, and thus they can heavily influence the mobility and bioavailability of zinc there. Therefore, ubiquitous soil fungus Aspergillus niger was selected as a test organism to evaluate the fungal interaction with ZnO NPs. As anticipated, the A. niger strain significantly affected the stability of particulate forms of ZnO due to the acidification of its environment. The influence of ZnO NPs on fungus was compared to the aqueous Zn cations and to bulk ZnO as well. Bulk ZnO had the least effect on fungal growth, while the response of A. niger to ZnO NPs was comparable with ionic zinc. Our results have shown that soil fungus can efficiently bioaccumulate Zn that was bioextracted from ZnO. Furthermore, it influences Zn bioavailability to plants by ZnO NPs transformation to stable biogenic minerals. Hence, a newly formed biogenic mineral phase of zinc oxalate was identified after the experiment with A. niger strain’s extracellular metabolites highlighting the fungal significance in zinc biogeochemistry.

Special Issue: Fungal Nanotechnology

“…As a result, Aspergillus niger, a common soil fungus, was chosen as a test organism to evaluate fungal interactions with ZnO NPs. As expected, the A. niger strain had a significant effect on the stability of particulate forms of ZnO due to the acidification of its environment [15]. The macrofungi-derived NPs produced by major mushroom species such as Agaricus bisporus, Pleurotus spp., Lentinus spp.…”

Application of Response Surface Methodology for Optimizing the Therapeutic Activity of ZnO Nanoparticles Biosynthesized from Aspergillus niger

“…The chitin/ZnO composites showed antibacterial properties against Gram-positive bacteria [ 52 ]. In another work, extracellular metabolites of A. niger were used to transform ZnO-NPs into a zinc oxalate [ 53 ]. The results show that due to the presence of high active metabolites, A. niger can biomineralize inorganic NPs and transform these NPs into more stable oxalate complexes.…”

A Review on Biofabrication of Zinc Nanoparticles, Its Mechanism and Recent Applications

“…In intracellular synthesis, transportation of metal ions within the cell takes place where they are reduced by enzymes present there which leads to increase in nuclei resulting in nanoparticles formation in the periplasmic space and cytoplasm [39]. Mukherjee et al [42] reported intracellular mechanism for NPs by Verticillium sp. Consisting of three steps trapping, bioreduction and capping.…”

“…Cell filtrate of this both fungal strain was treated with 2mM zinc acetate [Zn(CH3CO2)2] to form precipitate which was dried at 150˚C for 48h to be used for further investigation [45]. Identical method was used for the synthesis of ZnO NPs by using zinc nitrate hexahydrate [Zn (NO3)2.6H2O] with fungal filtrate of Xylaria acuta followed by heating the reaction mixture [42].…”