title: Characterization of a Clostridium beijerinckii spo0A mutant and its application for butyl butyrate production.
abstract: Spo0A is a master regulator that governs the metabolic shift of solventogenic Clostridium species such as Clostridium beijerinckii. Its disruption can thus potentially cause a significant alteration of cellular physiology as well as metabolic patterns. To investigate the specific effect of spo0A disruption in C. beijerinckii, a spo0A mutant of C. beijerinckii was characterized in this study. In a batch fermentation with pH control at 6.5, the spo0A mutant accumulated butyrate and butanol up to 8.96 g/L and 3.32 g/L, respectively from 60 g/L glucose. Noticing the unique phenotype of the spo0A mutant accumulating both butyrate and butanol at significant concentrations, we decided to use the spo0A mutant for the production of butyl butyrate that can be formed by the condensation of butyrate and butanol during the ABE fermentation in the presence of the enzyme lipase. Butyl butyrate is a value-added chemical that has numerous uses in the food and fragrance industry. Moreover, butyl butyrate as a biofuel is compatible with Jet A-1 aviation kerosene and used for biodiesel enrichment. In an initial trial of small-scale extractive batch fermentation using hexadecane as the extractant with supplementation of lipase CalB, the spo0A mutant was subjected to acid crash due to the butyrate accumulation, and thus produced only 98 mg/L butyl butyrate. To alleviate the butyrate toxicity, the biphasic medium was supplemented with 10 g/L CaCO3and 5 g/L butanol. The butyl butyrate production was then increased up to 2.73 g/L in the hexadecane layer. When continuous agitation was performed to enhance the esterification and extraction of butyl butyrate, 3.32 g/L butyl butyrate was obtained in the hexadecane layer. In this study, we successfully demonstrated the use of the C. beijerinckii spo0A mutant for the butyl butyrate production through the simultaneous ABE fermentation, condensation, and extraction. Biotechnol. Bioeng. 2017;114: 106-112. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Seung-Oh
authors.initials: SO
authors.lastname: Seo
authors.affiliation: Biosystems Engineering Department, Auburn University, Auburn, Alabama.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.|Departments of Bioengineering and Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Ting
authors.initials: T
authors.lastname: Lu
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.|The Integrated Bioprocessing Research Laboratory (IBRL), University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.
authors.forename: Hans P
authors.initials: HP
authors.lastname: Blaschek
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D000440:Butanols / Q000378:metabolism; D002087:Butyrates / Q000032:analysis / Q000378:metabolism*; D002119:Calcium Carbonate; D046970:Clostridium beijerinckii / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009154:Mutation / Q000235:genetics
chemical_list: D000440:Butanols; D002087:Butyrates; C022793:n-butyl n-butyrate; D002119:Calcium Carbonate; D005947:Glucose
keywords: ABE fermentation; Butyl butyrate production; Clostridium beijerinckii spo0A mutant