AUTHOR=Alves Joana I. , Visser Michael , Arantes Ana L. , Nijsse Bart , Plugge Caroline M. , Alves M. Madalena , Stams Alfons J. M. , Sousa Diana Z. 

TITLE=Effect of Sulfate on Carbon Monoxide Conversion by a Thermophilic Syngas-Fermenting Culture Dominated by a Desulfofundulus Species

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.588468

DOI=10.3389/fmicb.2020.588468

ISSN=1664-302X

ABSTRACT=<p>A syngas-degrading enrichment culture, culture T-Syn, was dominated by a bacterium closely related to <italic>Desulfofundulus australicus</italic> strain AB33<sup>T</sup> (98% 16S rRNA gene sequence identity). Culture T-Syn could convert high CO concentrations (from pCO ≈ 34 kPa to pCO ≈ 170 kPa), both in the absence and in the presence of sulfate as external electron acceptor. The products formed from CO conversion were H<sub>2</sub> and acetate. With sulfate, a lower H<sub>2</sub>/acetate ratio was observed in the product profile, but CO conversion rates were similar to those in the absence of sulfate. The ability of <italic>D. australicus</italic> strain AB33<sup>T</sup> to use CO was also investigated. <italic>D. australicus</italic> strain AB33<sup>T</sup> uses up to 40% CO (pCO ≈ 68 kPa) with sulfate and up to 20% CO (pCO ≈ 34 kPa) without sulfate. Comparison of the metagenome-assembled genome (MAG) of the <italic>Desulfofundulus</italic> sp. from T-Syn culture with the genome of <italic>D. australicus</italic> strain AB33<sup>T</sup> revealed high similarity, with an ANI value of 99% and only 32 unique genes in the genome of the <italic>Desulfofundulus</italic> sp. T-Syn. So far, only <italic>Desulfotomaculum nigrificans</italic> strain CO-1-SRB had been described to grow with CO with and without sulfate. This work further shows the carboxydotrophic potential of <italic>Desulfofundulus</italic> genus for CO conversion, both in sulfate-rich and low-sulfate environments.</p>