Hints for understanding microalgal phosphate-resilience from Micractinium simplicissimum IPPAS C-2056 (Trebouxiophyceae) isolated from a phosphorus-polluted site

Failure of <em>Micractinium simplicissimum </em>Phosphate Resilience upon Abrupt Re-Feeding of its Phosphorus-Starved Cultures

“…To gain a deeper insight into the rearrangements of P pools in the culture of the M. simplicissimum under our experimental conditions, an electron microscopy studies of cells sampled at the key stages of the experiment (see Figure 1) was carried out (Figures 5, A1, A2). The ultrastructure of the M. simplicissimum pre-culture cells was similar to that of the cells grown under similar conditions [10]. Briefly, the preculture consisted of individual round-shaped cells containing a single nucleus, parietal chloroplast with a centrally located pyrenoid; the culture also contained occasional autosporangia (Figures 5 a and 6 a, b).…”

“…The Micractinium simplicissimum strain IPPAS C-2056 recently isolated from a P-polluted site served as a model organism for this study. The cultures of the M. simplicissimum grown in P-replete media exhibit a very high Pi-resilience [10]. In our recent experiments on P starvation, we observed a sudden culture death upon replenishment of Pi to the Pdepleted culture of the M. simplicissimum.…”

“…The P-deprived cultures demonstrated the onset of stationary phase due to the P limitation by the 10 th day of incubation. The Pi was replenished to the P-deprived cultures to the final concentration of 0.8 g L -1 which is far below the level potentially toxic to the M. simplicissimum [10]). The pH of the cultures remained in the range 6.7-7.7 throughout the experiment, so the Pi added to the cultures is expected to be readily available for the uptake by the microalgal cells.…”

“…Possibly as a side effect of these adaptations, microalgae became remarkably resilient to high levels of external Pi by far exceeding its environmental concentrations (1 g L -1 and more [10]). Some microalgal species found in P-polluted sites display very high Pi tolerance (see e.g.…”

“…Some microalgal species found in P-polluted sites display very high Pi tolerance (see e.g. [10]). It makes microalgae a powerful vehicle for biocapture of P from waste streams [11] increasing thereby sustainability of using P resources which is currently notoriously low (< 20%) [12].…”