The pyrE mutant strain is a uracil auxotroph and resistant to FOA-mediated toxicity.
(F) The rate of ammonium consumption by the wild-type and ∆yeaG mutant strain is directly proportional to their respective 'recovery' growth characteristics.
A Cj0977 mutant strain is fully motile but significantly reduced in the invasion of intestinal epithelial cells in vitro.
Therefore, the ∆yeaG mutant strain is less viable than the wild-type strain, because it, unlike the latter, exists in a single and metabolically active population following sustained N starvation (Figs 4 and 6A).
Next, to directly link the property of the ∆yeaG mutant strain is mediated by the differences in the levels of expression of mqsR/mqsA and dinJ/yafQ, we constructed ∆dinJ∆yafQ∆yeaG and ∆mqsR∆mqsA∆yeaG triple deletion mutants as well as a ∆dinJ∆yafQ∆mqsR∆mqsA∆yeaG quintuple deletion mutant.
We were able to revert the growth characteristics of the ∆yeaG mutant strain to that of the wild-type strain by complementing with inducible plasmid-borne yeaG (∆yeaG pBAD-yeaG), thereby demonstrating that the altered growth of the mutant strain is not due to any undesired effects caused by the deletion of the yeaG gene (Fig. 3A,B).
However the mutant strain is not stable and can reverse to the wild type.
In theory, the effect of anhydrotetracycline to the mutant strain is similar to the effect of d-cycloserine to the wild type strain.
Our results showed that when the WT and mutant were mixed, the overall fitness of the mutant strain is inferior to that of its WT (Fig. 2).
This suggests that the overall fitness of the mutant strain is inferior to that of its WT, when cultivated in co-culture in the conditions tested (i.e. initial ratios, nitrogen concentrations, cultivation conditions etc).
It is known, however, that the lack of the PHB polymerase (PhaC) activity in this mutant strain is associated with distinctly lower activities of β-ketothiolase (PhaA) and acetoacetyl-CoA reductase (PhaB) [66].
