title: High production of acetone-butanol-ethanol with high cell density culture by cell-recycling and bleeding.
abstract: A continuous acetone-butanol-ethanol (ABE) production system with high cell density obtained by cell-recycling of Clostridium saccharoperbutylacetonicum N1-4 has been studied. In conventional continuous culture of ABE without cell-recycling, the cell concentration was below 5.2 g l(-1) and the maximum ABE productivity was only 1.85 g l(-1)h(-1) at a dilution rate of 0.20 h(-1). To obtain a high cell density at a faster rate, we concentrated the solventogenic cells of the broth 10 times by membrane filtration and were able to obtain approximately 20 g l(-1) of active cells after only 12h of cultivation. Continuous culture with cell-recycling was then started, and the cell concentration increased gradually through cultivation to a value greater than 100 g l(-1). The maximum ABE productivity of 11.0 gl(-1)h(-1) was obtained at a dilution rate of 0.85 h(-1). However, a cell concentration greater than 100 gl(-1) resulted in heavy bubbling and broth outflow, which made it impossible to carry out continuous culture. Therefore, to maintain a stable cell concentration, cell-bleeding was performed together with cell-recycling. At dilution rates of 0.11h(-1) and above for cell-bleeding, continuous culture with cell-recycling could be operated for more than 200 h without strain degeneration and the overall volumetric ABE productivity of 7.55 gl(-1)h(-1) was achieved at an ABE concentration of 8.58 gl(-1).
authors.affiliation: Laboratory of Microbial Technology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tashiro
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Takeda
authors.forename: Genta
authors.initials: G
authors.lastname: Kobayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sonomoto
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D000096:Acetone / Q000378:metabolism*; D019149:Bioreactors; D001709:Biotechnology; D003013:Clostridium / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D015169:Colony Count, Microbial; D000431:Ethanol / Q000378:metabolism*; D007700:Kinetics
chemical_list: D000096:Acetone; D000431:Ethanol; D020001:1-Butanol