Mechanisms of ammonium assimilation by Chlorella vulgaris F1068: Isotope fractionation and proteomic approaches. (August 2015)

• Record Type: Journal Article
• Authors: Liu, Na; Li, Feng; Ge, Fei; Tao, Nengguo; Zhou, Qiongzhi; Wong, Minghung
• Is Part Of: Bioresource technology. Volume 190(2015)
• Page Start: 307
• Page End: 314
• Publication Date: 2015-08
• Subjects: Ammonium removal -- Microalgae -- 15N isotope fractionation -- Proteomic -- Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR); Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2015.04.024
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: The NH4 + -N concentrations affect the removal efficiency of NH4 + -N by algae. The NH4 + -N concentrations affect the biotransformation efficiency by algae. 15 N isotope fractionation effect depends on the NH4 + -N concentration. Glutamine synthase was a key enzyme for ammonium assimilation. Abstract: Removal of ammonium (NH4 + -N) by microalgae has evoked interest in wastewater treatment, however, the detailed mechanisms of ammonium assimilation remain mysterious. This study investigated the effects of NH4 + -N concentration on the removal and biotransformation efficiency by Chlorella vulgaris F1068, and explored the mechanisms by 15 N isotope fractionation and proteome approaches. The results showed NH4 + -N was efficiently removed (84.8%) by F1068 at 10 mg L −1 of NH4 + -N. The isotope enrichment factor ( ε = −2.37 ± 0.08‰) of 15 N isotope fractionation revealed 47.6% biotransformation at above condition, while 7.0% biotransformation at 4 mg L −1 of NH4 + -N ( ε = −1.63 ± 0.06‰). This was due to the different expression of glutamine synthetase, a key enzyme in ammonium assimilation, which was up-regulated 6.4-fold at proteome level and 18.0-fold at transcription level. The results will provide a better mechanistic understanding of ammonium assimilation by microalgae and this green technology is expected to reduce the burden of NH4 + -N removal for municipal sewage treatment plants.