title: Tracking the acetate threshold using DO-transient control during medium and high cell density cultivation of recombinant Escherichia coli in complex media.
abstract: DO-transient nutrient controllers use the dissolved oxygen signal to attempt acetate threshold tracking during fed-batch cultivation of recombinant E. coli. Here we apply DO-transient control to the production of Jembrana disease virus protein in complex Super Luria medium and compare performance against a high-limit pH-stat controller. For induction at medium cell density (harvest between 31 and 32.5 g dcw L) a total productivity of 0.27 g L h was achieved as compared to 0.24 g L h with the high-limit pH-stat. For induction at high cell density (harvest at 60 g dcw L), decreased productivity (0.12 g L h) was attributed to the effect of acetate accumulation on recombinant protein formation and a concomitant lowering of the critical growth rate. Our results suggest that complex media provides a difficult environment for the application of acetate threshold tracking DO-transient control because of difficulties in re-oxidizing acetate, and apparent localized production of acetate below the production threshold (as detected by the DO-transient controller as SPOUR(crit)). Configuring the DO-transient controller to avoid aggressive threshold probing is suggested as a means to improve performance and reduce acetate accumulation in complex media.
authors.affiliation: Hawaii Natural Energy Institute, University of Hawaii-Manoa, 1680 East West Road, POST 109, Honolulu, HI 96822, USA.
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Johnston
authors.forename: Meredith
authors.initials: M
authors.lastname: Stewart
authors.forename: Peter
authors.initials: P
authors.lastname: Lee
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cooney
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000465:Algorithms; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D002455:Cell Division / Q000502:physiology; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D005246:Feedback / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D011994:Recombinant Proteins / Q000096:biosynthesis; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000085:Acetates; D011994:Recombinant Proteins; D014764:Viral Proteins; D010100:Oxygen