Effects of temperature and salinity on the production of cell biomass, chlorophyll-a and intra- and extracellular nodularins (NOD) and nodulopeptin 901 produced by Nodularia spumigena KAC 66

Nodularia spumigena is one of the dominant toxic cyanobacteria which produce blooms in the Baltic Sea, a brackish water body, particularly in late summer. Nodularia spp. are known to produce hepatotoxic nodularins (NODs) and other bioactive peptides such as spumigins and nodulopeptins. In a recent study, three new nodulopeptins with a molecular weight of 899, 901 and 917 Da were characterized from N. spumigena KAC66. To gain further insight into the effects of environmental stress on growth and production of bioactive metabolites in N. spumigena KAC66, two parameters were investigated: temperature and salinity. It was found that growth conditions have a considerable effect on biomass and toxin levels of N. spumigena KAC66. Increasing temperature had a profound effect on NOD production with an increase from 22 to 25 °C resulting in a 50% decrease in intracellular NOD levels. At 30 °C, little or no NOD was detected. In contrast, while concentrations of nodulopeptin 901 decreased with increasing temperature, it was still detectable throughout the growth cycle at elevated temperatures. The light intensity of 13 μmol photons m−2 s−1, 22 °C and 11–20‰ salinity were optimal growth conditions to obtain maximum biomass, intra- and extracellular peptide productions. This is the first report to evaluate the effects of selected environmental parameters on NOD/nodulopeptin 901 productions which ultimately may be helpful to explain the distribution, control of natural blooms and toxin levels of N. spumigena in the Baltic Sea, as well as in laboratory based experiments.