In Gram-negative bacteria, a response to nutrient limitation is production of polyhydroxyalkanoates, storage compounds that are produced in unbalanced metabolic conditions [27,28]. In the present study, rprY mutant cells contained high levels of undecanoate, a subunit of a polyhydroxyalkanoate, which appeared to be a gene effect. Interestingly, polyhydroxyalkanoate production decreased the oxidative stress response in a psychrophilic Pseudomonas species by modulating the levels of reducing equivalents [29]. Thiamine levels were approximately five-fold lower in the mutant strain than in the parent, another effect of the rprY mutation. A link between thiamine and oxidative stress was provided by the observation that thiamine supplementation restored the growth of Salmonella enterica on paraquat, a superoxide-generator, the interpretation being that oxidative stress directly caused the thiamine requirement [30]. Our **data** would suggest that low levels of thiamine in the rprY mutant result from oxidative stress induced by the mutation, even in normal media.