title: Studies on plasmid stability and LTB production by recombinant Vibrio cholerae in batch and chemostat cultures: a lesson for optimizing conditions for chemical induction.
abstract: Plasmid content, its stability and the expression of B-subunit of Escherichia coli heat-labile enterotoxin (LTB) in Vibrio cholerae/r-pMMB68 system have been studied in batch as well as in chemostat cultures. Upon induction with isopropyl-beta-D-thiogalactopyranoside (IPTG), cultures secreted LTB into the extracellular milieu. Highest specific LTB production rate of 7.3 mg mg-1h-1 was achieved in batch culture induced at the late exponential growth phase. The plasmid pMMB68 was fairly stable up to 20 generations, even in the absence of selection pressure. Instability of the plasmid was accelerated in the presence of IPTG and at higher dilution rates. Maximum productivity of 2.1 mg l-1 h-1 was achieved in continuous culture, which remained constant at a range of dilution rates from 0.20 to 0.35 h-1.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal, India.
authors.forename: A
authors.initials: A
authors.lastname: Ramesh
authors.forename: A K
authors.initials: AK
authors.lastname: Panda
authors.forename: B R
authors.initials: BR
authors.lastname: Maiti
authors.forename: A
authors.initials: A
authors.lastname: Mukhopadhyay
mesh_terms: D000667:Ampicillin; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D002455:Cell Division; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D004768:Enterotoxins / Q000096:biosynthesis* / Q000235:genetics; D029968:Escherichia coli Proteins; D005947:Glucose; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D010957:Plasmids / Q000737:chemistry* / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D012641:Selection, Genetic; D014734:Vibrio cholerae / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D003470:Culture Media; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D007544:Isopropyl Thiogalactoside; D000667:Ampicillin; C027538:heat-labile enterotoxin, E coli; D005947:Glucose