The effect of environmental growth conditions on the segregational stabiIity of a recombinant Esckrichia
co&Bacillus subtilis shuttle plasmid pCPPS-31 which expresses carboxymethyl cellulase (CMCase) and contains the
neomycin resistance gene (Ne’), was studied in E. coli DHSa. The stability increased with the decrease in medium
complexity. Lowering culture temperatures had a negative effect on stability. Stability was maximum at 100 rpm and
a medium/flask volume ratio of 1:lO. A pH range of 5-8 had no significant effect on stability. The recombination
(ret) and gyrase (gyr) backgrounds of E. coli hosts had no apparent effect on plasmid stability. The plasmid was
structurally stable under all circumstances.