Influence of temperature, salinity and nutrient limitation on yessotoxin production and release by the dinoflagellate Protoceratium reticulatum in batch-cultures

Growth and bioactive secondary metabolites of arctic Protoceratium reticulatum (Dinophyceae)

“…For YTX of Protoceratium reticulatum, a significant amount was found in the culture medium, although the percentage of intracellular YTX of all strains at all experimental conditions was higher than extracellular YTX. This was observed as well for other strains of P. reticulatum (Paz et al, 2004(Paz et al, , 2013Guerrini et al, 2007;Rö der et al, 2012), although it has to be kept in mind that these authors did not report on extraction efficiency of their SPE method to quantify extracellular YTX and thus the true extracellular concentrations in their experiment might have been higher. A general feature observed for all Greenland isolates and in the studies cited above was an increase in intracellular YTX cell quota at stationary phase.…”

“…This might indicate an increased excretion of these compounds by actively growing cells, but it also might reflect an increased degradation of extracellular metabolites in old cultures as bacterial densities usually peak when algae become dense. In contrast, other studies (Paz et al, 2004;Guerrini et al, 2007) have found increasing per-cell extracellular concentrations of YTX in stationary phase, which is commonly discussed as a stress related release due to cell leakage or death. Clearly, more detailed studies are needed to fully evaluate the significance, variability, and potential role of extracellular YTX.…”

“…All these studies support the general conclusion that P. reticulatum is a temperate water species. Nevertheless, isolates from the Mediterranean, with maximum growth at 20 8C, were still growing at growing at 26 8C (Guerrini et al, 2007). Compared to the Greenland isolate, which died at 25 8C, this indicates that geographically different populations may differ in their temperature adaptation status.…”

“…In any case, growth rate is an important measure to quantify the effect of any environmental factor. Among those, temperature is important as it significantly influences phytoplankton dynamics and geographical distribution (Guerrini et al, 2007). For this reason one of the isolates was selected and tested for a wide range of temperatures to establish a base line of the physiology of this arctic P. reticulatum isolate.…”

“…Moreover, blooms of P. reticulatum have exclusively been reported from temperate areas, such as a bloom in Flødevigen (Norway) (Aasen et al, 2005), a bloom in northern Japan (Koike et al, 2006), or a bloom in northern Chile (Á lvarez et al, 2011), which all occurred at water temperatures of 13-21 8C. In addition to these in situ evidences, few laboratory studies have tested temperature effects on growth of P. reticulatum isolates from different locations, such as the Adriatic Sea (Guerrini et al, 2007), the North Sea (Rö der et al, 2012) and from NW Spain (Paz et al, 2006). All these studies support the general conclusion that P. reticulatum is a temperate water species.…”