Chromium tolerance and accumulation in Aspergillus flavus isolated from tannery effluent

J Basic Microbiol. 2020 Jan;60(1):58-71. doi: 10.1002/jobm.201900389. Epub 2019 Oct 16.

Abstract

Cr(VI) tolerance in Aspergillus flavus, strain SFL, isolated from tannery effluent was measured and compared with a reference strain of A. flavus, A1120. On solid medium, SFL had a high level of Cr(VI) tolerance (1,600 mg/L), which was 16 times that of A1120 and greater than most previously analyzed fungal strains. When in 100 mg/L of Cr(VI), SFL completely depleted Cr(VI) within 72 h while A1120 depleted 85% of Cr(VI). SFL was more effective in reducing extracellular Cr(VI) than A1120. While A1120 showed greater biosorption of Cr(VI) than SFL, intracellular accumulation was approximately 50% greater in SFL and was more energy-dependent than A1120. Cr(VI) modified the external surface of the hyphae. Cr speciation detected the presence of only Cr(III), corresponding to Cr(OH)3 , which precipitated on the hyphal surface. Cr(VI) bound to the functional groups carboxyl, amine, and hydroxyl in both SFL and A1120. Transmission electron microscopy energy-dispersive X-ray detected Cr on the fungal wall and within membrane-bound organelles of the cytoplasm. In conclusion, the greater tolerance of SFL to Cr(VI) relative to A1120 is due to more effective energy-dependant uptake of Cr(VI) into the cell and increased capacity of SFL to store Cr in intracellular vacuoles compared with A1120.

Keywords: Aspergillus flavus; Cr biosorption; Cr uptake; FTIR; SEM; TEM; XPS.

MeSH terms

  • Adsorption
  • Aspergillus flavus / metabolism*
  • Aspergillus flavus / ultrastructure
  • Chromium / metabolism*
  • Hyphae / metabolism
  • Hyphae / ultrastructure
  • Tanning
  • Waste Water / microbiology*
  • Water Pollutants, Chemical / metabolism*

Substances

  • Waste Water
  • Water Pollutants, Chemical
  • Chromium