Increased stability of pBR322-related plasmids in Escherichia coli W3101 grown in carrageenan gel beads |
| |
Authors: | Sami Sayadi Fadwa Berry Moncef Nasri Jean N. Barbotin Daniel Thomas |
| |
Affiliation: | Laboratoire de Technologie Enzymatique, U A no. 523 du CNRS, BP 649, Universitéde Technologie de Compiègne, 60206 Compiègne Cedex, France |
| |
Abstract: | Abstract The stability and the copy number of pBR322, pBR325 and pBR328 were studied during continous cultures of free and immobilized E. coli W3101 without selective pressure. In the free-cell system, it was found that pBR328 and pBR325-free E. coli cells appeared after a lag period. They rapidly overgrew the cultures and the plasmid copy number subsequently declined. On the other hand, an increase in the proportion of pBR322- carrying cells during a free continuous culture was observed. This increase correlated with that of plasmid copy number. By contrast, in the immobilized- cell system, plasmid free segregants were not detected in all the cases even after 250 generations. We have also shown that plasmid copy number remained constant and phenomena such as fluctuations or genetic modifications which occured after long term growth of bacteria in a free continuous culture could be avoided throughout cell immobilization. |
| |
Keywords: | pBR322-related plasmid Continuous culture Immobilized cell Plasmid stability Plasmid copy number |
本文献已被 ScienceDirect 等数据库收录! |
|