Title: Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

Abstract

ABSTRACT The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has previously been genetically modified to produce isobutyric acid (IBA) from carbon dioxide while obtaining energy from the oxidation of ferrous iron. Here, a combinatorial approach was used to explore the influence of medium composition in both batch and chemostat cultures in order to improve IBA yields (g IBA/mol Fe ²⁺ ) and productivities (g IBA/L/d). Medium pH, ferrous concentration (Fe ²⁺ ), and inclusion of iron chelators all had positive impact on the IBA yield. In batch experiments, gluconate was found to be a superior iron chelator because its use resulted in smaller excursions in pH. In batch cultures, IBA yields decreased linearly with increases in the final effective Fe ³⁺ concentrations. Chemostat cultures followed similar trends as observed in batch cultures. Specific cellular productivities were found to be a function of the steady state ORP (Oxidation‐reduction potential) of the growth medium, which is primarily determined by the Fe ³⁺ to Fe ²⁺ ratio. By operating at low ORP, chemostat cultures were able to achieve volumetric productivities as high as 3.8 ± 0.2 mg IBA/L/d which is a 14‐fold increase over the previously reported value. Biotechnol. Bioeng. 2016;113: 790–796. © 2015 Wiley Periodicals, Inc.

Authors:

Li, Xiaozheng ^[1]; West, Alan C. ^[1]; Banta, Scott ^[1]

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+ Show Author Affiliations

1. Department of Chemical Engineering Columbia University New York New York 10027

Publication Date:

Tue Sep 29 00:00:00 EDT 2015

Sponsoring Org.:

USDOE

OSTI Identifier:

1401154

Grant/Contract Number:  

DE‐AR0000060

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Biotechnology and Bioengineering

Additional Journal Information:

Journal Name: Biotechnology and Bioengineering Journal Volume: 113 Journal Issue: 4; Journal ID: ISSN 0006-3592

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

United States

Language:

English