The aim of the master's thesis was to develop and optimize a method for studying the influence of Pseudomonas putida GB-1 biofilm on the biocorrosion of different types of steel. We established a system for growing biofilm on four types of steel: martensitic 13-4, austenitic AISI 304, duplex 2507, and structural S235J. For analysis, we determined cell viability, surface coverage of optical slices in biofilm, and biofilm thickness using confocal laser scanning microscopy (CSLM), and checked for possible corrosion damage using scanning electron microscopy (SEM). We found that manganese oxidation growth medium was the most suitable medium for biofilm formation. After 16 days of incubation, the bacteria formed a biofilm on all steel types. The average cell viability was highest on structural steel S235J, which also had the thinnest biofilm. Among stainless steels, duplex steel 2507 had the lowest cell viability but the highest surface coverage of optical slices with bacterial cells. After extending the incubation to one month, the surface coverage of optical slices increased on all steel types, while the biofilm thickness decreased. Despite the successful biofilm formation, we did not detect any signs of microbiologically induced corrosion on any of the steel types. No changes were observed even after one month of incubation in rich LB medium, where bacterial growth was fastest. The results show that the P. putida GB-1 strain does not cause corrosion under the conditions used, while observations on structural steel indicate a possible protective effect of the biofilm. The development of corrosion would probably require longer incubation, different enviromental conditions for bacterial growth on the discs, or the use of a different bacterial strain.
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