Marker Retention service, also known as Plasmid Loss analysis service, is offered to determine the percentage of cells in a cell sample that contains a selectable marker such as antibiotic resistant gene. In microbial cell culture process, a bacteria stain may lose its antibiotic resistance due to the loss of its resistant-coding plasmid, an undesirable event in biologics manufacturing.
Test sample will be tested for the presence or absence of the selective marker, such as an antibiotic resistant gene coded in the plasmid in E. Coli. Test sample, positive, and negative cells will be plated to obtain isolated colonies. Results will be reported as the percentage of cells retaining the marker, or percentage of plasmid loss.
A report with the following information will be delivered: images of selective and non-selective growth plates, colony counts, and calculation of percentage of marker retention or plasmid loss.