ammonia tolerance on growth rate of marine microalga Chlorella vulgaris
Goto1, N. Nagao2*, F. Md. Yusoff2, M.S.
Kamarudin3, T. Katayama4, N. Kurosawa1, M.
Koyama5, K. Nakasaki5 and T. Toda1
1Faculty of Science
and Engineering, Soka University, Hachioji, Tokyo 192-8577, Japan
Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia,
43400 UPM Serdang, Selangor Daryl Ehsan, Malaysia
Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM
Serdang, Selangor Daryl Ehsan, Malaysia
4Graduate School of
Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo
Transdisciplinary Science and Engineering, School of Environment and Society,
Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan
Author E-mail: email@example.com
Paper received : 09.06.2017
Revised received : 15.08.2017
Re-revised received :
Accepted : 28.12.2017
Aim: In order to
evaluate the effects of ammonia on microalgae growth, chlorella vulgaris
was cultivated in ammonium nitrogen.
Methodology: The marine
microalgae, Chlorella vulgaris was cultivated in algal media
containing increasing concentrations of ammonium concentrations at 320, 640,
960, 1600 mg l-1, with free ammonia concentrations of 0.64 to 2.97
mM and pH ranging from 7.78 to 7.82. An addition ammonia treatment was 1600
mg l-1 that had a free ammonia concentration of 13.30 mM, while a
control was NaNO3 at 100 mg l-1.
Results: C. vulgaris
grew faster when cultured using ammonium nitrogen than nitrate nitrogen. The
dry weight of C. vulgaris increased even under extremely high ammonium
conditions of 1600 mg-N l-1, which initially contained 2.97 mM
free ammonia and reached around 4 g-ds l-1. Algal growth was
inhibited in the beginning of the experiment at the highest initial free
ammonia concentration of 13.30 mM. However, the cell density increased 2 days
later when free ammonia concentration decreased to 3.7 mM due to decrease in
pH from 8.48 to 7.88, and the maximum area productivity of 21.12 g-ds m-2
d-1 was observed.
Interpretation: These results
showed that C. vulgaris could maintain high productivity even in high
free ammonia concentrations of 3.7 mM. Because of the high tolerance for free
ammonia compared with other microalgae, C. vulgaris can be used for
the aquaculture industry by removing ammonia from wastewater, and thus
improving the water quality.