title: Improvement of the butanol production selectivity and butanol to acetone ratio (B:A) by addition of electron carriers in the batch culture of a new local isolate of Clostridium acetobutylicum YM1.
abstract: Improvement in the butanol production selectivity or enhanced butanol:acetone ratio (B:A) is desirable in acetone-butanol-ethanol (ABE) fermentation by Clostridium strains. In this study, artificial electron carriers were added to the fermentation medium of a new isolate of Clostridium acetobutylicum YM1 in order to improve the butanol yield and B:A ratio. The results revealed that medium supplementation with electron carriers changed the metabolism flux of electron and carbon in ABE fermentation by YM1. A decrease in acetone production, which subsequently improved the B:A ratio, was observed. Further improvement in the butanol production and B:A ratios were obtained when the fermentation medium was supplemented with butyric acid. The maximum butanol production (18.20 ± 1.38 g/L) was gained when a combination of methyl red and butyric acid was added. Although the addition of benzyl viologen (0.1 mM) and butyric acid resulted in high a B:A ratio of 16:1 (800% increment compared with the conventional 2:1 ratio), the addition of benzyl viologen to the culture after 4 h resulted in the production of 18.05 g/L butanol. Manipulating the metabolic flux to butanol through the addition of electron carriers could become an alternative strategy to achieve higher butanol productivity and improve the B:A ratio.
authors.affiliation: School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia; Department of Applied Microbiology, Faculty of Applied Sciences, Taiz University, 6803, Taiz, Yemen.
authors.forename: Najeeb Kaid
authors.initials: NK
authors.lastname: Nasser Al-Shorgani
authors.affiliation: Department of Chemical and Process Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
authors.forename: Mohd Sahaid
authors.initials: MS
authors.lastname: Kalil
authors.affiliation: School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
authors.forename: Wan Mohtar
authors.initials: WM
authors.lastname: Wan Yusoff
authors.affiliation: Department of Chemical and Process Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
authors.forename: Hafiza
authors.initials: H
authors.lastname: Shukor
authors.affiliation: School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia. Electronic address: aidilabdulhamid@gmail.com.
authors.forename: Aidil Abdul
authors.initials: AA
authors.lastname: Hamid
mesh_terms: D000096:Acetone / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D001594:Benzyl Viologen / Q000378:metabolism; D000440:Butanols / Q000378:metabolism*; D020148:Butyric Acid / Q000378:metabolism; D046969:Clostridium acetobutylicum / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D004583:Electrons; D005285:Fermentation; D012988:Soil Microbiology
chemical_list: D000440:Butanols; D003470:Culture Media; D020148:Butyric Acid; D001594:Benzyl Viologen; D000096:Acetone
keywords: B:A ratio; Butanol; Clostridium acetobutylicum YM1; Electron carriers; Renewable energy