title: Injection of air into the headspace improves fermentation of phosphoric acid pretreated sugarcane bagasse by Escherichia coli MM170.
abstract: Microaeration (injecting air into the headspace) improved the fermentation of hemicellulose hydrolysates obtained from the phosphoric acid pretreatment of sugarcane bagasse at 170°C for 10 min. In addition, with 10% slurries of phosphoric acid pretreated bagasse (180°C, 10 min), air injection into the headspace promoted xylose utilization and increased ethanol yields from 0.16 to 0.20 g ethanol/g bagasse dry weight using a liquefaction plus simultaneous saccharification and co-fermentation process (L+SScF). This process was scaled up to 80 L using slurries of acid pretreated bagasse (96 h incubation; 0.6L of air/min into the headspace) with ethanol yields of 312-347 L (82-92 gal) per tone (dry matter), corresponding to 0.25 and 0.27 g/g bagasse (dry weight). Injection of small amounts of air into the headspace may provide a convenient alternative to subsurface sparging that avoids problems of foaming, sparger hygiene, flotation of particulates, and phase separation.
authors.affiliation: Department of Microbiology & Cell Science, University of Florida, Box 110700, Gainesville, FL 32611, USA. ismael.nieves@ufl.edu
authors.forename: I U
authors.initials: IU
authors.lastname: Nieves
authors.forename: C C
authors.initials: CC
authors.lastname: Geddes
authors.forename: M T
authors.initials: MT
authors.lastname: Mullinnix
authors.forename: R W
authors.initials: RW
authors.lastname: Hoffman
authors.forename: Z
authors.initials: Z
authors.lastname: Tong
authors.forename: E
authors.initials: E
authors.lastname: Castro
authors.forename: K T
authors.initials: KT
authors.lastname: Shanmugam
authors.forename: L O
authors.initials: LO
authors.lastname: Ingram
mesh_terms: D000388:Air; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D002241:Carbohydrates / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects*; D006868:Hydrolysis; D010756:Phosphoric Acids / Q000494:pharmacology*; D031786:Saccharum / Q000737:chemistry*; D013227:Steam; D013447:Sulfites
chemical_list: D002241:Carbohydrates; D010756:Phosphoric Acids; D013227:Steam; D013447:Sulfites; C005200:sodium metabisulfite; D002482:Cellulose; C027433:bagasse; C030242:phosphoric acid