Effect of NH4Cl supplementation on growth, photosynthesis, and triacylglycerol content in Chlamydomonas reinhardtii under mixotrophic cultivation
Issued Date
2024-10-03
Resource Type
eISSN
13652672
Scopus ID
2-s2.0-85205604306
Pubmed ID
39257021
Journal Title
Journal of applied microbiology
Volume
135
Issue
10
Rights Holder(s)
SCOPUS
Bibliographic Citation
Journal of applied microbiology Vol.135 No.10 (2024)
Suggested Citation
Sittisaree W., Yokthongwattana K., Aonbangkhen C., Yingchutrakul Y., Krobthong S. Effect of NH4Cl supplementation on growth, photosynthesis, and triacylglycerol content in Chlamydomonas reinhardtii under mixotrophic cultivation. Journal of applied microbiology Vol.135 No.10 (2024). doi:10.1093/jambio/lxae233 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/101573
Title
Effect of NH4Cl supplementation on growth, photosynthesis, and triacylglycerol content in Chlamydomonas reinhardtii under mixotrophic cultivation
Corresponding Author(s)
Other Contributor(s)
Abstract
AIM: Ammonium chloride (NH4Cl) is one of the nitrogen sources for microalgal cultivation. An excessive amounts of NH4Cl are toxic for microalgae. However, combining mixotrophic conditions and excessive quantities of NH4Cl positively affects microalgal biomass and lipid production. In this study, we investigated the impact of NH4Cl on the growth, biomass, and triglyceride (TAG) content of the green microalga Chlamydomonas reinhardtii especially under mixotrophic conditions. METHODS AND RESULTS: Under photoautotrophic conditions (without organic carbon supplementation), adding 25 mM NH4Cl had no significant effect on microalgal growth or TAG content. However, under mixotrophic condition (with acetate supplementation), NH4Cl interfered with microalgal growth while inducing TAG content. To explore these effects further, we conducted a two-step cultivation process and found that NH4Cl reduced microalgal growth, but induced total lipid and TAG content, especially after 4-day cultivation. The photosynthesis performances showed that NH4Cl completely inhibited oxygen evolution on day 4. However, NH4Cl slightly reduced the Fv/Fm ratio indicating that the NH4Cl supplementation directly affects microalgal photosynthesis. To investigate the TAG induction effect by NH4Cl, we compared the protein expression profiles of microalgae grown mixotrophically with and without 25 mM NH4Cl using a proteomics approach. This analysis identified 1782 proteins, with putative acetate uptake transporter GFY5 and acyl-coenzyme A oxidase being overexpressed in the NH4Cl-treated group. CONCLUSION: These findings suggested that NH4Cl supplementation may stimulate acetate utilization and fatty acid synthesis pathways in microalgae cells. Our study indicated that NH4Cl supplementation can induce microalgal biomass and lipid production, particularly when combined with mixotrophic conditions.