Studies on the aerobic utilization of synthesis gas (syngas) by wild type and recombinant strains of Ralstonia eutropha H16.

Daniel Heinrich,Matthias Raberg,Alexander Steinbüchel

doi:10.1111/1751-7915.12873

Daniel Heinrich, Matthias Raberg + Show 1 more

Open Access

https://doi.org/10.1111/1751-7915.12873

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Abstract

SummaryThe biotechnical platform strain Ralstonia eutropha H16 was genetically engineered to express a cox subcluster of the carboxydotrophic Oligotropha carboxidovorans OM5, including (i) the structural genes coxM, ‐S and ‐L, coding for an aerobic carbon monoxide dehydrogenase (CODH) and (ii) the genes coxD, ‐E, ‐F and ‐G, essential for the maturation of CODH. The cox Oc genes expressed under control of the CO 2‐inducible promoter PL enabled R. eutropha to oxidize CO to CO 2 for the use as carbon source, as demonstrated by 13 CO experiments, but the recombinant strains remained dependent on H2 as external energy supply. Therefore, a synthetic metabolism, which could be described as ‘carboxyhydrogenotrophic’, was established in R. eutropha. With this extension of the bacterium's substrate range, growth in CO‐, H2‐ and CO 2‐containing artificial synthesis gas atmosphere was enhanced, and poly(3‐hydroxybutyrate) synthesis was increased by more than 20%.

Highlights

The b-proteobacterium Ralstonia eutropha H16, currently named as Cupriavidus necator H16, represents a model organism for autotrophic lifestyle and has been studied extensively for its efficient utilization of carbon dioxide and hydrogen as carbon and energy sources (Friedrich and Schwartz, 1993)
Carboxydotrophic bacteria oxidize CO with H2O to CO2 and 2 H+ + 2 eÀ by a carbon monoxide dehydrogenase (CODH), thereby obtaining energy and carbon, that is usually fixed in the CBB cycle
The CODH-associated proteins of the model organism for carboxydotrophy, O. carboxidovorans OM5, are encoded in a single 14.5-kbp cox gene cluster, which is located on the organism’s megaplasmid pHCG3 (Fig. S1; Fuhrmann et al, 2003). This cluster includes the structural genes for CODH, coxM, coxS and coxL, as well as genes that code for proteins mediating the post-translational maturation of CODH

Summary

The biotechnical platform strain Ralstonia eutropha H16 was genetically engineered to express a cox subcluster of the carboxydotrophic Oligotropha carboxidovorans OM5, including (i) the structural genes coxM, -S and -L, coding for an aerobic carbon monoxide dehydrogenase (CODH) and (ii) the genes coxD, -E, -F and -G, essential for the maturation of CODH. The coxOc genes expressed under control of the CO2-inducible promoter PL enabled R. eutropha to oxidize CO to CO2 for the use as carbon source, as demonstrated by 13CO experiments, but the recombinant strains remained dependent on H2 as external energy supply. A synthetic metabolism, which could be described as ‘carboxyhydrogenotrophic’, was established in R. eutropha. With this extension of the bacterium’s substrate range, growth in CO-, H2- and CO2-containing artificial synthesis gas atmosphere was enhanced, and poly(3-hydroxybutyrate) synthesis was increased by more than 20%

Introduction

Results and discussion

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