title: Isolation and screening of carboxydotrophs isolated from composts and their potential for butanol synthesis.
abstract: Carboxydotrophs are known for their ability to convert carbon monoxide (CO) to butanol through fermentation. Such a platform offers a promising alternative approach to biofuel production from synthesis gas feedstocks. In this study, carboxydotrophs were isolated from various manure compost. Out of 500 isolates, only 11 carboxydotrophs (7 mesophiles and 4 thermophiles) were found to utilize CO as the sole source of carbon and energy. To assess the biochemical basis for their ability to produce biofuel (butanol), the level of activities of CO dehydrogenase (CODH), hydrogenase and butanol dehydrogenase (BDH) enzymes for these isolates against the known carboxydotroph, Butyribacterium methylotrophicum was assessed. All isolates showed evidence of enzyme activities (0.16-2.20 micromol min(-1)), with the majority exhibiting higher activities compared with the known carboxydotroph, B. methylotrophicum (0.33-0.71 micromol min(-1)). The level of activities for CODH and BDH ranged from 0.163-3.59 micromolmin(-1) and 0.19-2.2 micromolmin(-1), respectively. Three isolates (M7-1, T2-22, and T3-14) demonstrated enzymatic activity three to seven times higher than B. methylotrophicum. Of these, T2-22 exhibited the highest BDH activity and shows great promise in the conversion of toxic CO into butanol more so than other carboxytotrophs known thus far. This study revealed some biochemical basis for butanol production from CO by carboxydotrophs. However, more research is needed to discover a direct biological route for butanol production from CO to strengthen their potential for synthesis gas bioprocessing. Follow-up work will focus on whole-genome sequencing of the promising isolate T2-22 to provide system-level insights into how carboxydotrophs utilize and regulate their molecular machineries for butanol production.
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Nguyen
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Fatime
authors.initials: F
authors.lastname: Ala
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Cisley
authors.initials: C
authors.lastname: Cardwell
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Darlene
authors.initials: D
authors.lastname: Cai
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Katelyn M
authors.initials: KM
authors.lastname: McKindles
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Lotvola
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Hodges
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Natural Sciences, University of Michigan, Dearborn, MI, USA.
authors.forename: Sonia M
authors.initials: SM
authors.lastname: Tiquia-Arashiro
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D056804:Biofuels; D000440:Butanols / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D005740:Gases / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D012987:Soil; D012988:Soil Microbiology
chemical_list: D056804:Biofuels; D000440:Butanols; D005740:Gases; D009097:Multienzyme Complexes; D012987:Soil; D002244:Carbon; D000429:Alcohol Oxidoreductases; C060833:butanol dehydrogenase; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D005947:Glucose