title: Improved conversion efficiencies for n-fatty acid reduction to primary alcohols by the solventogenic acetogen "Clostridium ragsdalei".
abstract: "Clostridium ragsdalei" is an acetogen that ferments synthesis gas (syngas, predominantly H2:CO2:CO) to ethanol, acetate, and cell mass. Previous research showed that C. ragsdalei could also convert propionic acid to 1-propanol and butyric acid to 1-butanol at conversion efficiencies of 72.3 and 21.0 percent, respectively. Our research showed that C. ragsdalei can also reduce pentanoic and hexanoic acid to the corresponding primary alcohols. This reduction occurred independently of growth in an optimized medium with headspace gas exchange (vented and gassed with CO) every 48 h. Under these conditions, conversion efficiencies increased to 97 and 100 % for propionic and butyric acid, respectively. The conversion efficiencies for pentanoic and hexanoic acid to 1-pentanol and 1-hexanol, respectively, were 82 and 62 %. C. ragsdalei also reduced acetone to 2-propanol at a conversion efficiency of 100 %. Further, we showed that C. ragsdalei uses an aldehyde oxidoreductase-like enzyme to reduce n-fatty acids to the aldehyde intermediates in a reaction that requires ferredoxin and exogenous CO.
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA, catisom@ou.edu.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Isom
authors.forename: Mark A
authors.initials: MA
authors.lastname: Nanny
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Tanner
mesh_terms: D020001:1-Butanol / Q000378:metabolism; D019840:2-Propanol / Q000378:metabolism; D019342:Acetic Acid / Q000378:metabolism; D000096:Acetone / Q000378:metabolism; D000426:Alcohol Dehydrogenase / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D000595:Amino Acid Sequence; D020148:Butyric Acid / Q000378:metabolism; D002208:Caproates / Q000378:metabolism; D003013:Clostridium / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry*; D005285:Fermentation; D005740:Gases / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D010421:Pentanoic Acids / Q000378:metabolism; D000439:Pentanols / Q000378:metabolism; D011422:Propionates / Q000378:metabolism
chemical_list: D002208:Caproates; D005227:Fatty Acids; D005740:Gases; D009097:Multienzyme Complexes; D010421:Pentanoic Acids; D000439:Pentanols; D011422:Propionates; D020148:Butyric Acid; D000096:Acetone; C037652:hexanoic acid; D000431:Ethanol; D020001:1-Butanol; D000426:Alcohol Dehydrogenase; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; C029658:propionic acid; C024999:n-pentanol; D019840:2-Propanol; D019342:Acetic Acid