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1.
BMC Biotechnol ; 14: 6, 2014 Jan 21.
Article in English | MEDLINE | ID: mdl-24444109

ABSTRACT

BACKGROUND: Penicillin G acylase (PGA) is used industrially to catalyze the hydrolysis of penicillin G to obtain 6-aminopenicillanic acid. In Escherichia coli, the most-studied microorganism for PGA production, this enzyme accumulates in the periplasmic cell space, and temperature plays an important role in the correct synthesis of its subunits. RESULTS: This work investigates the influence of medium composition, cultivation strategy, and temperature on PGA production by recombinant E. coli cells. Shake flask cultures carried out using induction temperatures ranging from 18 to 28°C revealed that the specific enzyme activity achieved at 20°C (3000 IU gDCW-1) was 6-fold higher than the value obtained at 28°C. Auto-induction and high cell density fed-batch bioreactor cultures were performed using the selected induction temperature, with both defined and complex media, and IPTG and lactose as inducers. Final biomass concentrations of 100 and 120 gDCW L-1, and maximum enzyme productivities of 7800 and 5556 IU L-1 h-1, were achieved for high cell density cultures using complex and defined media, respectively. CONCLUSIONS: To the best of our knowledge, the volumetric enzyme activity and productivity values achieved using the complex medium are the highest ever reported for PGA production using E. coli. Overall PGA recovery yields of 64 and 72% after purification were achieved for crude extracts obtained from cells cultivated in defined and complex media, respectively. The complex medium was the most cost-effective for PGA production, and could be used in both high cell density and straightforward auto-induction protocols.


Subject(s)
Batch Cell Culture Techniques/methods , Escherichia coli/metabolism , Penicillin Amidase/biosynthesis , Bioreactors , Culture Media , Temperature
2.
Curr Microbiol ; 65(4): 369-74, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22729211

ABSTRACT

This work reports the cloning, expression, and purification of a 42-kDa fragment of the SpaA protein from Erysipelothrix rhusiopathiae, the main antigenic candidate for a subunit vaccine against swine erysipelas. The use of an auto-induction protocol to improve heterologous protein expression in recombinant Escherichia coli cultures was also investigated. The cellular growth pattern and metabolite formation were evaluated under different induction conditions. The His-tagged protein was over-expressed as inclusion bodies, and was purified by a single chromatography step under denaturing conditions. Auto-induction conditions were shown to be an excellent process strategy, leading to a high level of rSpaA expression (about 25 % of total cellular protein content) in a short period of time.


Subject(s)
Antigens, Bacterial/isolation & purification , Bacterial Proteins/genetics , Erysipelothrix/genetics , Swine Erysipelas/microbiology , Animals , Antigens, Bacterial/chemistry , Antigens, Bacterial/genetics , Bacterial Proteins/chemistry , Chromatography, Affinity , Cloning, Molecular , Escherichia coli/genetics , Gene Expression , Inclusion Bodies , Molecular Weight , Protein Denaturation , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/isolation & purification , Swine , Swine Erysipelas/immunology
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