The defence of bacteria Comamonas sp against oxidative stress with the induction of catalases

The production of catalases as a response to oxidative stressors was tested in different phases of growth cycle of the bacterial strains: C. terrigena N3H and N1C isolated from soils contaminated with crude oil, C. testosteroni, the natural isolate from a sludge of waste water treatment plant, and C. testosteroni 1931(T)-ATCC 11996 obtained from the cultures collection. We found that the induction of catalatic and peroxidatic activities were dependent on an individual strain, its growth phase, and also on the kind of oxidant. 0.5 mM peracetic acid (PAA) and 0.5 mM hydrogen peroxide (11202) induced the highest catalase activity in the strain C. terrigena N3H in the middle exponential phase of the growth (approx. 5 or 3 fold) in comparison to controls. In contrast paraquat (PQ) and cadmium (Cd) influenced the expression of catalases mainly in the later phases of growth. H2O2 induced significant increase of the peroxidatic activity in the middle exponential phase in C. terrigena N3H and in the late stationary phase of the wild type strain of C. testosteroni. Cumene hydroperoxide and hydrogen peroxide induced significant increase in peroxidatic activity in the middle exponential phase of C. terrigena N3H. Homogenates of the collection strain C. testosteroni did not exhibit a significant increase in the low levels of catalatic and peroxidatic activities. We analysed the role of catalase isozymes in response to oxidative stress, with native gradient polyacrylamide electrophoresis. In the case of C. testosteroni strains only one band with molecular weight of 150 kDa was identified that corresponds to the constitutively expressed enzyme. During their growth, the strains of C. terrigena N3H and N1C induced one, two or three forms of catalase, as the response to oxidative stress. The appearance of the protein band with higher molecular weight approximately 240 kDa was typical for the later phases of growth. The results suggest, that despite the fact that the tested strains belong taxonomically to the same genus or species, they exhibit significant diversity and respond distinctly to the oxidative stress.