title: Poly(3-hydroxybutyrate) synthesis from glycerol by a recombinant Escherichia coli arcA mutant in fed-batch microaerobic cultures.
abstract: Poly(3-hydroxybutyrate) (PHB) synthesis was analyzed under microaerobic conditions in a recombinant Escherichia coli arcA mutant using glycerol as the main carbon source. The effect of several additives was assessed in a semi-synthetic medium by the 'one-factor-at-a-time' technique. Casein amino acids (CAS) concentration was an important factor influencing both growth and PHB accumulation. Three factors exerting a statistically significant influence on PHB synthesis were selected by using a Plackett-Burman screening design [glycerol, CAS, and initial cell dry weight (CDW) concentrations] and then optimized through a Box-Wilson design. Under such optimized conditions (22.02 g l(-1) glycerol, 1.78 g l(-1) CAS, and 1.83 g l(-1) inoculum) microaerobic batch cultures gave rise to 8.37 g l(-1) CDW and 3.52 g l(-1) PHB in 48 h (PHB content of 42%) in a benchtop bioreactor. Further improvements in microaerobic PHB accumulation were obtained in fed-batch cultures, in which glycerol was added to maintain its concentration above 5 g l(-1). After 60 h, CDW and PHB concentration reached 21.17 and 10.81 g l(-1), respectively, which results in a PHB content of 51%. Microaerobic fed-batch cultures allowed a 2.57-fold increase in volumetric productivity when compared with batch cultures.
authors.affiliation: Departamento de Química Biológica, Universidad de Buenos Aires, Ciudad Universitaria, 1428, Buenos Aires, Argentina.
authors.forename: Pablo I
authors.initials: PI
authors.lastname: Nikel
authors.forename: M Julia
authors.initials: MJ
authors.lastname: Pettinari
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Galvagno
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Méndez
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000378:metabolism*; D007218:Industrial Microbiology; D008962:Models, Theoretical; D009154:Mutation; D011091:Polyesters / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D000094122:Polyhydroxybutyrates
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D005947:Glucose; D005990:Glycerol; D006885:Hydroxybutyrates; D011091:Polyesters; D012097:Repressor Proteins; C041610:arcA protein, E coli; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates