I conducted two experiments to see how KCl and NaCl concentration of 0.5M, respectively, affect the bacterial growth. I used JM109 E.coli strain, and JM109 with pBR322. For NaCl the bacterial growth was better in case of JM109, in case of 0.5M KCl, pBR322 bearing strain grew better than plasmid free one. I am not sure now which salt is more toxic to bacteria overall. Also, do you know why pBR322 bearing strain grew better than plasmid free strain in 0.5M of KCl?? I would assume before the experiment that presence of plasmid would slow down the growth (extra DNA to replicate) but I was proven wrong. Are there any genes on pBR322 that help bacteria to cope with KCl stress and respond to this stress better than JM109 or anything like that? Do you know any literature that would allow me to compare my results and help me to understand this problem??
Thanks in advance!
Ah, I used salt free media as controls (in any case I noted better growth for JM109 than the plasmid containing strain)