Exploiting microbial hyperthermophilicity to produce an industrial chemical, using hydrogen and carbon dioxide

Abstract

Microorganisms can be engineered to produce useful products, including chemicals and fuels from sugars derived from renewable feedstocks, such as plant biomass. An alternative method is to use low potential reducing power from nonbiomass sources, such as hydrogen gas or electricity, to reduce carbon dioxide directly into products. This approach circumvents the overall low efficiency of photosynthesis and the production of sugar intermediates. Although significant advances have been made in manipulating microorganisms to produce useful products from organic substrates, engineering them to use carbon dioxide and hydrogen gas has not been reported. Herein, we describe a unique temperature-dependent approach that confers on a microorganism (the archaeon Pyrococcus furiosus, which grows optimally on carbohydrates at 100°C) the capacity to use carbon dioxide, a reaction that it does not accomplish naturally. This was achieved by the heterologous expression of five genes of the carbon fixation cycle of the archaeon Metallosphaera sedula, which grows autotrophically at 73°C. The engineered P. furiosus strain is able to use hydrogen gas and incorporate carbon dioxide into 3-hydroxypropionic acid, one of the top 12 industrial chemical building blocks. The reaction can be accomplished by cell-free extracts and by whole cells of the recombinant P. furiosus strain. Moreover, it is carried out some 30°C below the optimal growth temperature of the organism in conditions that support only minimal growth but maintain sufficient metabolic activity to sustain the production of 3-hydroxypropionate. The approach described here can be expanded to produce important organic chemicals, all through biological activation of carbon dioxide.

Single gene insertion drives bioalcohol production by a thermophilic archaeon

“…The resulting PCR products were digested with AscI and SphI, and then ligated into plasmid pGL007 (14) to make plasmids pMB403SLP and pMB404SLP. Plasmid pMB407SLP for construction of strain A ( Fig.…”

“…P. furiosus was recently metabolically engineered to generate end products other than acetate in a temperature-controlled manner without the need for chemical inducers. Lactate was produced from glucose, and 3-hydroxypropionate was produced from carbon dioxide and glucose, using heterologously expressed enzymes encoded by foreign genes obtained from microbes that grow near 75°C (13,14). At 98°C, the foreign enzymes were inactive and the engineered P. furiosus strains generated acetate, but near 70°C, the engineered strains produced either lactate or 3-hydroxypropionate instead.…”

A warm welcome for alternative CO2 fixation pathways in microbial biotechnology

“…Hereto, in recent years a few attempts have been made, such as the introduction of the complete natural 3‐hydroxypropionate bi‐cycle in Escherichia coli by the Silver laboratory, which did not yet yield a completely functional pathway (Mattozzi et al ., 2013). In the Adams laboratory, a section of the natural 3‐hydroxypropionate/4‐hydroxybutyrate cycle was successfully introduced in the heterotrophic thermophile Pyrococcus furiosus ; however, this short section is insufficient to support complete autotrophic growth (Keller et al ., 2013). …”

Synthetic biology for CO2 fixation

“…Each sub-pathway was found to be functional, which provided a basis for the potential synthesis of CO2-fixing E. coli. In the same year, Keller et al expressed a part of the 3-hydroxypropionate/4-hydroxybutyrate cycle from the archaea Metallosphaera sedula (optimum growth temperature of 73°C) in another archaea Pyrococcus furiosus (optimum growth temperature of 100°C) (Keller et al, 2013). This engineered strain can synthesize a valuable industrial chemical, 3-hydroxypropionic acid, from CO2, using hydrogen as the energy source.…”