Proteomic Insights into the Adaptation of Acidithiobacillus ferridurans to Municipal Solid Waste Incineration Residues for Enhanced Bioleaching Efficiency

Acidithiobacillus spp. have traditionally
been
utilized to extract metals from mineral ores through bioleaching.
This process has recently expanded to include artificial ores, such
as those derived from municipal solid waste incineration (MSWI) residues.
Previous studies have indicated that microbial adaptation enhances
bioleaching efficiency, prompting this study to identify proteins
involved in the adaptation of A. ferridurans to MSWI residues. We employed data-independent acquisition-parallel
accumulation serial fragmentation to determine the proteomic response
of A. ferridurans DSM 583 to three
distinct materials: bottom ash (BA), kettle ash (KA), and filter ash
(FA), which represent typical MSWI residues. Our findings indicate
that, irrespective of the residue type, a suite of membrane transporters,
porins, efflux pumps, and specific electron and cation transfer proteins
was notably upregulated. The upregulation of certain proteins involved
in anaerobic pathways suggested the development of a spontaneous microaerobic
environment, which minimally impacted the bioleaching efficiency.
Additionally, the adaptation was most efficient at half the target
FA concentration, marked by a significant increase in the detoxification
and efflux systems required by microorganisms to tolerate high heavy
metal concentrations. Given that metal recovery peaked at lower FA
concentrations for most metals of interest, further adaptation at
the level of protein expression may not be warranted for improved
bioleaching outcomes.