title: Betaine tripled the volumetric productivity of D(-)-lactate by Escherichia coli strain SZ132 in mineral salts medium.
abstract: Osmotic stress restricts glycolytic flux, growth (rate and yield), D-lactate productivity, and D-lactate tolerance in Escherichia coli B strain SZ132 during batch fermentation in mineral salts medium with 10% (w/v) sugar. Addition of 1 mM: betaine, a non-metabolized protective osmolyte, doubled cell yield, increased specific productivity of D-lactate and glycolytic flux by 50%, and tripled volumetric productivity (from 8.6 to 25.7 mmol l(-1) h(-1); 0.8 to 2.3 g l(-1) h(-1)). Glycolytic flux and specific productivity in mineral salts medium with betaine exceeded that in Luria broth, substantially eliminating the need for complex nutrients during D-lactate production. In mineral salts medium supplemented with betaine, SZ132 produced approximately 1 mol D-lactate (90 g) per 100 g sugar (glucose or sucrose).
authors.affiliation: Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA.
authors.forename: S
authors.initials: S
authors.lastname: Zhou
authors.forename: T B
authors.initials: TB
authors.lastname: Grabar
authors.forename: K T
authors.initials: KT
authors.lastname: Shanmugam
authors.forename: L O
authors.initials: LO
authors.lastname: Ingram
mesh_terms: D001622:Betaine / Q000494:pharmacology*; D001709:Biotechnology; D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D007700:Kinetics; D008903:Minerals; D009997:Osmotic Pressure; D012492:Salts; D013395:Sucrose / Q000378:metabolism
chemical_list: D003470:Culture Media; D008903:Minerals; D012492:Salts; D001622:Betaine; D013395:Sucrose; D005947:Glucose