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Dispersion of sulfur enables sulfur oxidation before iron oxidation in Acidithiobacillus ferrooxidans: A valuable formulation for the genetic engineering toolbox
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  • Yuta Inaba,
  • Timothy Kernan,
  • Alan West,
  • Scott Banta
Yuta Inaba
Columbia University
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Timothy Kernan
Columbia University
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Alan West
Columbia University
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Scott Banta
Columbia University
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Abstract

Acidithiobacillus ferrooxidans are acidophilic chemolithoautotrophs that are commonly reported to exhibit diauxic population growth behavior where ferrous iron is oxidized before elemental sulfur when both are available, despite the higher energy content of sulfur. We have discovered sulfur dispersion formulations that enables sulfur oxidation before ferrous iron oxidation. The oxidation of dispersed sulfur can lower the culture pH within days below the range where aerobic ferrous iron oxidation can occur so that ferric iron reduction occurs which had previously been reported over extended incubation periods with untreated sulfur. Therefore, we demonstrate that this substrate utilization pattern is strongly dependent on the cell loading in relation to sulfur concentration, sulfur surface hydrophobicity, and the pH of the culture. Our dispersed sulfur formulation, lig-sulfur, can be used to support the rapid antibiotic selection of plasmid-transformed cells, which is not possible in liquid cultures where ferrous iron is the main source of energy for these acidophiles. Furthermore, we find that media containing lig-sulfur supports higher production of green fluorescent protein (GFP) compared to media containing ferrous iron. The use of dispersed sulfur is a valuable new tool for the development of engineered A. ferrooxidans strains and it provides a new method to control iron and sulfur oxidation behaviors.

Peer review status:ACCEPTED

22 Feb 2021Submitted to Biotechnology and Bioengineering
23 Feb 2021Submission Checks Completed
23 Feb 2021Assigned to Editor
04 Mar 2021Reviewer(s) Assigned
02 Apr 2021Review(s) Completed, Editorial Evaluation Pending
02 Apr 2021Editorial Decision: Revise Major
28 May 20211st Revision Received
29 May 2021Submission Checks Completed
29 May 2021Assigned to Editor
01 Jun 2021Review(s) Completed, Editorial Evaluation Pending
01 Jun 2021Editorial Decision: Accept