Transcriptomic profiles of Clostridium ljungdahlii during lithotrophic growth with syngas or H-2 and CO2 compared to organotrophic growth with fructose

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Aklujkar, Muktak
Leang, Ching
Shrestha, Pravin M.
Shrestha, Minita
Lovley, Derek R.

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2017

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Clostridium ljungdahlii derives energy by lithotrophic and organotrophic acetogenesis. C. ljungdahlii was grown organotrophically with fructose and also lithotrophically, either with syngas - a gas mixture containing hydrogen (H-2), carbon dioxide (CO2), and carbon monoxide (CO), or with H-2 and CO2. Gene expression was compared quantitatively by microarrays using RNA extracted from all three conditions. Gene expression with fructose and with H-2/CO2 was compared by RNA-Seq. Upregulated genes with both syngas and H-2/CO2 (compared to fructose) point to the urea cycle, uptake and degradation of peptides and amino acids, response to sulfur starvation, potentially NADPH-producing pathways involving (S)-malate and ornithine, quorum sensing, sporulation, and cell wall remodeling, suggesting a global and multicellular response to lithotrophic conditions. With syngas, the upregulated (R)-lactate dehydrogenase gene represents a route of electron transfer from ferredoxin to NAD. With H-2/CO2, flavodoxin and histidine biosynthesis genes were upregulated. Downregulated genes corresponded to an intracytoplasmic microcompartment for disposal of methylglyoxal, a toxic byproduct of glycolysis, as 1-propanol. Several cytoplasmic and membrane-associated redox-active protein genes were differentially regulated. The transcriptomic profiles of C. ljungdahlii in lithotrophic and organotrophic growth modes indicate large-scale physiological and metabolic differences, observations that may guide biofuel and commodity chemical production with this species.

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Aklujkar, M., Leang, C., Shrestha, P. M., Shrestha, M., & Lovley, D. R. (2017). Transcriptomic profiles of Clostridium ljungdahlii during lithotrophic growth with syngas or H2 and CO2 compared to organotrophic growth with fructose. Scientific Reports, 7(1). doi:10.1038/s41598-017-12712-w

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Creative Commons Attribution 4.0 International

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2045-2322

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