Aims: The present work aimed to study the effects of cultivation conditions on the haemolytic activities of Pseudoalteromonas issachenkonii.
Methods and results: The kinetics of growth and haemolytic activities was investigated on sea-salts and NaCl-based nutrient media supplemented with either starch, or KBr over a period of 140 h. The first haemolytic activity occurred when bacterial cells reached the late stationary phase. The second haemolytic activity was observed in marine broth (MB) after 110 h of incubation. Addition of Fe to the culture medium neither affected bacterial growth nor reduced the haemolytic activity. However, the activity was enhanced in the presence of iron chelator. The second haemolytic activity was not affected by Ca2+, or inhibited by chymotrypsin or EDTA.
Conclusions: The production of haemolysins by P. issachenkonii was greater on MB and was dependent on both the medium composition and time of incubation. The second haemolytic activity was heat stable, nonproteinaceous, calcium-independent and was regulated by Fe.
Significance and impact of the study: The results demonstrated the importance of optimization of both the media composition and monitoring the haemolytic activity over a prolonged cultivation time to detect different types of haemolysins.