Issue 9, 2023

Syngas fermentation to ethanol: CODH/AdhE1 gene expression and microbial community dynamics

Abstract

Biosynthesis of ethanol through syngas fermentation employing enriched microbial consortia offers resilience to operate under non-sterile conditions with energy efficiency. Gas fermentation was performed by varying C1 feedstock with reference to selective enrichment of microbial consortia to maximize ethanol production with simultaneous process parameter optimization. Three different operating conditions (R1-CO2 + HCO3, R2-syngas, and R3-syngas + HCO3) were evaluated using diverse shock-based enrichment strategies (heat-shock, acid-shock and BESA). R2 and R3 systems showed potential for ethanologenic conversion of C1 gases. The highest ethanol (0.38 g L−1) and acetic acid (2.1 g L−1) yields were obtained in the R3 conditions using BESA-treated culture. Upregulation of genes involved in the Wood–Ljungdahl pathway, specifically alcohol dehydrogenase (AdhE1), under the treated conditions correlated with ethanol synthesis. Over-expression of the Ni-protein subunit (CODH) and Fdhl in the treated conditions demonstrated their role in the selective production of ethanol and acetate. Analysis of the microbial community revealed that the R3 conditions showed abundant phyla such as Firmicutes and Actinobacteria, and members of the carboxydotrophs, which possess the coding sequences of the upregulated genes. The treated conditions exhibited a three-fold increase in ethanol biosynthesis with an inorganic carbon fixation rate of 66 mg L−1 h−1, indicating efficient conversion of C1 substrate by the enriched biocatalyst. Higher relative expression and dominance of carboxydotrophs in the microbial diversity depicted the metabolic inclination of enriched biocatalysts towards the conversion of C1 gases.

Graphical abstract: Syngas fermentation to ethanol: CODH/AdhE1 gene expression and microbial community dynamics

Supplementary files

Article information

Article type
Paper
Submitted
07 4月 2023
Accepted
14 7月 2023
First published
10 8月 2023
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Adv., 2023,2, 1247-1260

Syngas fermentation to ethanol: CODH/AdhE1 gene expression and microbial community dynamics

A. Tharak, R. Katakojwala and S. V. Mohan, Environ. Sci.: Adv., 2023, 2, 1247 DOI: 10.1039/D3VA00080J

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements