@article{SpijkermanLukasWacker2017,
  author    = {Spijkerman, Elly and Lukas, Marcus and Wacker, Alexander},
  title     = {Ecophysiological strategies for growth under varying light and organic carbon supply in two species of green microalgae differing in their motility},
  series = {Phytochemistry : an international journal of plant biochemistry},
  volume    = {144},
  journal   = {Phytochemistry : an international journal of plant biochemistry},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0031-9422},
  doi       = {10.1016/j.phytochem.2017.08.018},
  pages     = {43 -- 51},
  year      = {2017},
  abstract  = {Mixing events in stratified lakes result in microalgae being exposed to varying conditions in light and organic carbon concentrations. Stratified lakes consist of an upper illuminated strata and a lower, darker strata where organic carbon accumulates. Therefore, in this contribution we explore the importance of dissolved organic carbon for growth under various light intensities by measuring some ecophysiological adaptations in two green microalgae. We compared the non-motile Chlorella vulgaris with the flagellated Chlamydomonas acidophila under auto-, mixo-, and heterotrophic growth conditions. In both algae the maximum photosynthetic and growth rates were highest under mixotrophy, and both algae appeared inhibited in their phosphorus acquisition under heterotrophy. Heterotrophic conditions provoked the largest differences as C. vulgaris produced chlorophyll a in darkness and grew as well as in autotrophic conditions, whereas Chl. acidophila bleached and could not grow heterotrophically. Although the fatty acid composition of both phytoplankton species differed, both species reacted in a similar way to changes in their growth conditions, mainly by a decrease of C18:3n-3 and an increase of C18:1n-9 from auto- to heterotrophic conditions. The two contrasting responses within the group of green microalgae suggest that dissolved organic carbon has a high deterministic potential to explain the survival and behaviour of green algae in the deeper strata of lakes.},
  language  = {en}
}
@article{LachmannMaberlySpijkerman2017,
  author    = {Lachmann, Sabrina C. and Maberly, Stephen C. and Spijkerman, Elly},
  title     = {Species-specific influence of P-i-status on inorganic carbon acquisition in microalgae (Chlorophyceae)},
  series = {Botany},
  volume    = {95},
  journal   = {Botany},
  publisher = {NRC Research Press},
  address   = {Ottawa},
  issn      = {1916-2790},
  doi       = {10.1139/cjb-2017-0082},
  pages     = {943 -- 952},
  year      = {2017},
  abstract  = {Inorganic phosphorus (P-i) is often the primary limiting nutrient in freshwater ecosystems. Since P(i-)limitation affects energy transduction, and inorganic carbon (C-i) acquisition can be energy demanding, C(i-)acquisition strategies were compared in four species of green algae grown under P-i-replete and P-i-limited conditions predominantly at low and partly at high CO2. Although P-i-limitation was evident by the 10-fold higher cellular C:P ratio and enhanced phosphatase activity, it only decreased C-i-acquisition to a small extent. Nonetheless, the effects of Pi-limitation on both CO2 and HCO3- acquisition were demonstrated. Decreased CO2 acquisition under conditions of Pi limitation was mainly visible in the maximum uptake rate (V-max) and, for the neutrophile Scenedesmus vacuolatus, in the affinity for CO2 acquisition. Discrimination against C-13 was higher under P-i-limited, high CO2 conditions, compared with P-i-replete, highCO(2) conditions, in Chlamydomonas acidophila and S. vacuolatus. In the pH-drift experiments, HCO3- acquisition was reduced in P-i-limited C. reinhardtii. In general, energy demanding bicarbonate uptake was indicated by the less strong discrimination against (13)Cunder lowCO(2) conditions in the neutrophiles (HCO3- users), separating them from the acidophilic or acidotolerant species (CO2 users). The high variability of the influence of Pi supply among different green algal species is linked to their species-specific C(i-)acquisition strategies.},
  language  = {en}
}