Amino acid supplementation decreases plasmid retention in Escherichia coli

✍ Scribed by J. Shu; M. L. Shuler

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 551 KB
• Volume: 40
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/bit.260401009

✦ Synopsis

Abstract

The effect of amino acid supplementation on plasmid stability in Escherichia coli B/r was tested experimentally. Comparisons of experimental results to computer‐predicted values were made using a detailed, structured single‐cell model. The plasmid, pDW17 (a pBR322 derivative with a mutated tac promoter controlling the β‐lactamase gene), was used. In chemostat cultures, the amino acid supplemented cultures were always less stable than those grown in minimal medium. This effect was not a growth rate effect, as increasing growth rate imsproves stability for both cultures in minimal medium and in amino acid supplemented medium. The computer model also predicted a decrease in stability due to amino acid supplementation. The model also predicts that amino acid supplementation, combined with moderately strong plasmid‐encoded protein expresion, results in a depletion of low‐molecular‐weight organics compared with plasmid‐free cells. In minimal medium the same level of plasmid‐encoded protein synthesis results in a strong reduction in amino acid pools compared with plasmid‐free cells. With amino acid supplementation the growth differential between plasmid‐bearing and plasmid‐free cells may be due to an “energy limitation,” while in minimal medium the size of the growth rate differential may be due to a “building block” limitation. © 1992 John Wiley & Sons, Inc.