Strain and bioprocess improvement of a thermophilic anaerobe for the production of ethanol from wood.

Autor: Herring CD; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA., Kenealy WR; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Verdezyne, Carlsbad, CA USA., Joe Shaw A; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Novogy Inc, Cambridge, MA 02138 USA., Covalla SF; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA., Olson DG; Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA ; Bioenergy Science Center, Oak Ridge, TN USA., Zhang J; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Genzyme, Cambridge, MA USA., Ryan Sillers W; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Myriant Corporation, Quincy, MA USA., Tsakraklides V; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Novogy Inc, Cambridge, MA 02138 USA., Bardsley JS; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA., Rogers SR; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA., Thorne PG; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA., Johnson JP; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Washington, DC, USA., Foster A; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA., Shikhare ID; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Nalco Champion, Houston, TX USA., Klingeman DM; Bioenergy Science Center, Oak Ridge, TN USA ; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA., Brown SD; Bioenergy Science Center, Oak Ridge, TN USA ; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA., Davison BH; Bioenergy Science Center, Oak Ridge, TN USA ; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA., Lynd LR; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA ; Bioenergy Science Center, Oak Ridge, TN USA., Hogsett DA; Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA ; Novozymes Inc, Davis, CA USA.
Jazyk: angličtina
Zdroj: Biotechnology for biofuels [Biotechnol Biofuels] 2016 Jun 16; Vol. 9, pp. 125. Date of Electronic Publication: 2016 Jun 16 (Print Publication: 2016).
DOI: 10.1186/s13068-016-0536-8
Abstrakt: Background: The thermophilic, anaerobic bacterium Thermoanaerobacterium saccharolyticum digests hemicellulose and utilizes the major sugars present in biomass. It was previously engineered to produce ethanol at yields equivalent to yeast. While saccharolytic anaerobes have been long studied as potential biomass-fermenting organisms, development efforts for commercial ethanol production have not been reported.
Results: Here, we describe the highest ethanol titers achieved from T. saccharolyticum during a 4-year project to develop it for industrial production of ethanol from pre-treated hardwood at 51-55 °C. We describe organism and bioprocess development efforts undertaken to improve ethanol production. The final strain M2886 was generated by removing genes for exopolysaccharide synthesis, the regulator perR, and re-introduction of phosphotransacetylase and acetate kinase into the methyglyoxal synthase gene. It was also subject to multiple rounds of adaptation and selection, resulting in mutations later identified by resequencing. The highest ethanol titer achieved was 70 g/L in batch culture with a mixture of cellobiose and maltodextrin. In a "mock hydrolysate" Simultaneous Saccharification and Fermentation (SSF) with Sigmacell-20, glucose, xylose, and acetic acid, an ethanol titer of 61 g/L was achieved, at 92 % of theoretical yield. Fungal cellulases were rapidly inactivated under these conditions and had to be supplemented with cellulosomes from C. thermocellum. Ethanol titers of 31 g/L were reached in a 100 L SSF of pre-treated hardwood and 26 g/L in a fermentation of a hardwood hemicellulose extract.
Conclusions: This study demonstrates that thermophilic anaerobes are capable of producing ethanol at high yield and at titers greater than 60 g/L from purified substrates, but additional work is needed to produce the same ethanol titers from pre-treated hardwood.
Databáze: MEDLINE
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