title: Ethanol production from glycerol-containing biodiesel waste by Klebsiella variicola shows maximum productivity under alkaline conditions.
abstract: Biodiesel fuel (BDF) waste contains large amounts of crude glycerol as a by-product, and has a high alkaline pH. With regard to microbial conversion of ethanol from BDF-derived glycerol, bacteria that can produce ethanol at alkaline pH have not been reported to date. Isolation of bacteria that shows maximum productivity under alkaline conditions is essential to effective production of ethanol from BDF-derived glycerol. In this study, we isolated the Klebsiella variicola TB-83 strain, which demonstrated maximum ethanol productivity at alkaline pH. Strain TB-83 showed effective usage of crude glycerol with maximum ethanol production at pH 8.0-9.0, and the culture pH was finally neutralized by formate, a by-product. In addition, the ethanol productivity of strain TB-83 under various culture conditions was investigated. Ethanol production was more efficient with the addition of yeast extract. Strain TB-83 produced 9.8 g/L ethanol (0.86 mol/mol glycerol) from cooking oil-derived BDF waste. Ethanol production from cooking oil-derived BDF waste was higher than that of new frying oil-derived BDF and pure-glycerol. This is the first report to demonstrate that the K. variicola strain TB-83 has the ability to produce ethanol from glycerol at alkaline pH.
authors.affiliation: Faculty of Life and Environmental Sciences (Bioindustrial Sciences), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Faculty of Life and Environmental Sciences (Bioindustrial Sciences), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Nishikawa
authors.affiliation: Faculty of Life and Environmental Sciences (Bioindustrial Sciences), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Seta
authors.affiliation: Tsukuba Environmental Microorganism Institute, 8-1 Sakuragaoka, Tsukuba, Ibaraki 300-1271, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Shigeno
authors.affiliation: Faculty of Life and Environmental Sciences (Bioindustrial Sciences), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan. Electronic address: nakajima.toshiaki.ga@u.tsukuba.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakajima-Kambe
mesh_terms: D000468:Alkalies / Q000494:pharmacology*; D001483:Base Sequence; D061249:Batch Cell Culture Techniques; D056804:Biofuels / Q000382:microbiology*; D001709:Biotechnology / Q000379:methods*; D000431:Ethanol / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007709:Klebsiella / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D055442:Metabolome / Q000187:drug effects; D010802:Phylogeny; D011189:Potassium Chloride / Q000494:pharmacology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012492:Salts / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D014866:Waste Products
chemical_list: D000468:Alkalies; D056804:Biofuels; D012336:RNA, Ribosomal, 16S; D012492:Salts; D014866:Waste Products; D000431:Ethanol; D012965:Sodium Chloride; D011189:Potassium Chloride; D005990:Glycerol