2,3-Butanediol Production by Acetogenic Bacteria, an Alternative Route to Chemical Synthesis, Using Industrial Waste Gas

Abstract

2,3-Butanediol (23BD) is a high-value chemical usually produced petrochemically but which can also be synthesized by some bacteria. To date, the best microbial 23BD production rates have been observed using pathogenic bacteria in fermentation systems that depend on sugars as the carbon and energy sources for product synthesis. Here we present evidence of 23BD production by three nonpathogenic acetogenic Clostridium species-Clostridium autoethanogenum, C. ljungdahlii, and C. ragsdalei-using carbon monoxide-containing industrial waste gases or syngas as the sole source of carbon and energy. Through an analysis of the C. ljungdahlii genome, the complete pathway from carbon monoxide to 23BD has been proposed. Homologues of the genes involved in this pathway were also confirmed for the other two species investigated. A gene expression study demonstrates a correlation between mRNA accumulation from 23BD biosynthetic genes and the onset of 23BD production, while a broader expression study of Wood-Ljungdahl pathway genes provides a transcription-level view of one of the oldest existing biochemical pathways.

Evaluation of Clostridium ljungdahlii DSM 13528 reference genes in gene expression studies by qRT-PCR

“…qRT-PCR has been performed to study of the expression levels of genes involved in 2,3-butanediol production in one acetogenic bacterium; in this study, gukl and fotl were used to normalize the transcriptional abundance of the target genes (20). However, neither of these genes had been previously validated in other acetogenic bacteria.…”

“…Genomic DNA was extracted as previously described (20). Total RNA was isolated with the RNA mini kit (Qiagen, Hilden, Germany) according to the manufacturer's instructions.…”

“…ljungdahlii DSM 13528 fixes CO and CO 2 through the WoodLjungdahl pathway and converts syngas into acetyl-CoA, a precursor for the production of many useful chemicals, such as ethanol (17), acetate (18), butanol (19), 2,3-butanediol (20) and other byproducts. The solvents generated by C. ljungdahlii DSM 13528 are autotoxic, and thus, the strain has evolved mechanisms to acclimate to these stresses (19,20). The publication of the C. ljungdahlii DSM 13528 genome has permitted the identification of the genes involved in carbon fixation, sugar metabolism, solvent synthesis, quorum sensing and two-component signal system, among others.…”

Catalytic routes towards acrylic acid, adipic acid and ε-caprolactam starting from biorenewables

“…162 Currently, LanzaTech has a 55 klpa pilot plant in New Zealand and a 380 klpa plant in China, where carbon monoxide waste gas is fermented to ethanol and 2,3-butanediol (2,3-BDO). 163 Direct carbon monoxide fermentation to 1,3-butadiene and the catalytic dehydration of 2,3-BDO are also being investigated (eqn (47)). DSM's ALTAM process (ALTernative caprolactAM) consists of carbonylation of 1,3-butadiene to obtain methyl-3-pentanoate.…”

Syngas Fermentation: A Microbial Conversion Process of Gaseous Substrates to Various Products

“…Butanol is sought as a "drop-in" biofuel for use in existing petroleum infrastructure, as a solvent and as precursor for subsequent synthesis. Propionic acid, propanol, hexanoic acid, hexanol, acetone, isobutanol, butanediol, amino and fatty acids are other potential products proposed from syngas fermentation [34,35,[105][106][107]. A biological water-gas shift is proposed to produce H 2 [108], and syngas can be biologically converted to methane [109] so that syngas energy and subsequent products might be obtained from biological conversion of natural gas.…”