Microbial communities of acidic post-mining environments and their use in laterite bioreduction

their impact on the environment and the possibility of remediating
such areas. Such a hostile environment is also a source of acidophilic
microorganisms that can dissolve minerals that might be applied in
the extractive metallurgy of low-grade oxide ores. Therefore, the
study used autochthonic microorganisms isolated from water and
sediment samples taken from places affected by acid mine drainage.
The acidophiles were isolated under aerobic and anaerobic
conditions. Genomic analysis revealed low prokaryotic diversity. The
genera with a relative abundance greater than 1% were
Acidithiobacillus (39.8-84.2%), Ferrimicrobium (26.4-34.4%),
Acidiphilium (8.31-28.8%), and Leptospirillum (9.6-32.1%). Aerobic
bacteria were adapted to reduce iron(III) under a nitrogen atmosphere
and the presence of elemental sulfur as an electron donor. It was
shown that increasing the amount of sulfur (1-5 g) had little effect on
the process kinetics. In anaerobic bottom sediments, Sulfobacillus
(45.7%) and Acidisphaera (32.7%) predominated. Microorganisms
showed the fastest reduction activity when glycerol was used as an
electron donor. Four weeks of anaerobic-controlled bioreduction of
laterites yielded nickel and magnesium at 33.3% and 77.3%,
respectively, which could have potential applications in the
processing of laterites.