TY  - JOUR
A1  - Lachmann, Sabrina C.
A1  - Mettler-Altmann, Tabea
A1  - Wacker, Alexander
A1  - Spijkerman, Elly
T1  - Nitrate or ammonium
BT  - Influences of nitrogen source on the physiology of a green alga
JF  - Ecology and evolution
N2  - In freshwaters, algal species are exposed to different inorganic nitrogen (Ni) sources whose incorporation varies in biochemical energy demand. We hypothesized that due to the lesser energy requirement of ammonium (NH4+)-use, in contrast to nitrate (NO3-)-use, more energy remains for other metabolic processes, especially under CO2-and phosphorus (Pi) limiting conditions. Therefore, we tested differences in cell characteristics of the green alga Chlamydomonas acidophila grown on NH4+ or NO3- under covariation of CO2 and Pi-supply in order to determine limitations, in a full-factorial design. As expected, results revealed higher carbon fixation rates for NH4+ grown cells compared to growth with NO3- under low CO2 conditions. NO3- -grown cells accumulated more of the nine analyzed amino acids, especially under Pi-limited conditions, compared to cells provided with NH4+. This is probably due to a slower protein synthesis in cells provided with NO3-. In contrast to our expectations, compared to NH4+ -grown cells NO3- -grown cells had higher photosynthetic efficiency under Pi-limitation. In conclusion, growth on the Ni-source NH4+ did not result in a clearly enhanced Ci-assimilation, as it was highly dependent on Pi and CO2 conditions (replete or limited). Results are potentially connected to the fact that C. acidophila is able to use only CO2 as its inorganic carbon (Ci) source.
KW  - amino acids
KW  - carbon uptake kinetics
KW  - CO2 conditions
KW  - nitrogen
KW  - phosphorus limitation
Y1  - 2019
U6  - https://doi.org/10.1002/ece3.4790
SN  - 2045-7758
VL  - 9
IS  - 3
PB  - Wiley
CY  - Hoboken
ER  -