title: Iron feeding optimization and plasmid stability in production of recombinant bacterial magnetic particles by Magnetospirillum magneticum AMB-1 in fed-batch culture.
abstract: The production of bacterial magnetic particles (BMPs) by recombinant Magnetospirillum magneticum AMB-1 harboring the plasmid pKML was enhanced in pH-regulated fed-batch culture. The addition of fresh nutrients was feedback-controlled as a function of the pH of the culture. The yield of BMPs was optimized by adjusting the rate of ferric iron addition. Feeding ferric quinate at 15.4 microg/min resulted ina BMP yield of 7.5 mg/l, which is the highest yield so far reported. Expression of a plasmid-encoded fusion protein and segregation of the plasmid during bacterial growth here both stable during, fed-batch culture. More than 75 % of the cells retained the plasmid for 130 h under antibiotic-free conditions. In addition, the fusion protein permitting the display of a specific protein on the BMP surface was also stably expressed.
authors.affiliation: Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Takeyama
authors.forename: T
authors.initials: T
authors.lastname: Matsunaga