title: Enhanced production of recombinant aspartase of Aeromonas media NFB-5 in a stirred tank reactor.
abstract: Aspartase gene (aspA) from Aeromonas media NFB-5 was cloned and expressed in Escherichia coli BL21 using pET21b(+) expression vector. Maximum production of aspartase was obtained at shake-flask after 5 h of IPTG (1.5 mM) induction at 37°C and by supplementing the media with KH2PO4 (0.3%, w/v) and K2HPO4 (0.3%, w/v). Further production was investigated at a laboratory scale stirred tank reactor using response surface methodology (RSM). Agitation (130-270 rpm), aeration (0.30-1.70 vvm) and IPTG induction time (3-7 h) was optimized. Optimal levels of agitation (250 rpm), aeration (1.25 vvm) and induction time (6h) were determined by statistical analysis of the experimental data. More than 7-fold increase in recombinant aspartase (1234 U/g wet weight) was observed than the parent strain (172 U/g wet wt). Homogenized immobilized permeabilized recombinant cells (566 mg/g wet cells) produced more L-aspartic acid as compared to permeabilized recombinant free cells (154 mg/g wet cells).
authors.affiliation: Carbohydrate and Protein Biotechnology Laboratory, Department of Biotechnology, Punjabi University, Patiala, India. rssingh11@lycos.com
authors.forename: Ram Sarup
authors.initials: RS
authors.lastname: Singh
authors.forename: Mukesh
authors.initials: M
authors.lastname: Yadav
mesh_terms: D000333:Aeromonas / Q000201:enzymology* / Q000235:genetics; D001220:Aspartate Ammonia-Lyase / Q000096:biosynthesis* / Q000235:genetics*; D019149:Bioreactors; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000378:metabolism*; D010710:Phosphates; D017680:Potassium Compounds; D011994:Recombinant Proteins / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D011994:Recombinant Proteins; C013216:potassium phosphate; D001220:Aspartate Ammonia-Lyase