The growth and lipid productivity of Chlorella pyrenoidosa enhanced by plant hormones under ammonium stress

Abstract

The high level of ammonium is a serious threat to algal lipid production when low quality water sources like piggery anaerobic digestion effluents were used as algal growth medium. Here, we aimed to investigate the effect of plant hormones (including indole‐3‐acide, cytokinin, and abscisic acid) on algal cells under ammonium stress particularly in respect to algal biomass and lipid productivities. Compared to those without hormones, the presence of plant hormones promotes algal growth under low levels of ammonium regardless of pH conditions. Exogenous plant hormones help in conferring tolerance to stress caused by high levels of ammonium and overcome the loss of algal productivities. Compared to the control, the lipid productivity increased by 298%, 637%, and 533% at pH 7, pH 8, and pH 9, respectively. In addition, the application of plant hormones suggested that indole‐3‐acide and cytokinin significantly increase cell density of algae subjected to ammonium stress while abscisic acid enhances the lipid accumulation. The results here demonstrate that it would be favorable alternative to grow algae for large‐scale biofuel production in low‐quality wastewater containing high ammonium content with the help of plant hormones. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1187–1193, 2017