Effects of C/N ratio on the growth and protein accumulation of heterotrophic Chlorella in broken rice hydrolysate

Yihui Cai, Ligong Zhai, Xiaoman Fang, Kangping Wu, Yuhuan Liu, Xian Cui, Yunpu Wang, Zhigang Yu, Roger Ruan, Tongying Liu, Qi Zhang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Background: Microalgae protein is considered as a sustainable alternative to animal protein in the future. Using waste for microalgal culture can upgrade low-value raw materials into high-value products, helping to offset the cost of microalgal protein production. In this study we explored the feasibility of using microalgae heterotrophic fermentation to convert broken rice hydrolysate (BRH) into protein. Results: The results showed that the increase of BRH supplemental ratio was beneficial to the increase of biomass production but not beneficial to the increase of intracellular protein content. To further improve protein production, the effect of C/N ratio on intracellular protein accumulation was studied. It was found that low C/N ratio was beneficial to the synthesis of glutamate in microalgae cells, which in turn promoted the anabolism of other amino acids and further the protein. When the C/N ratio was 12:1, the biomass productivity and protein content could reach a higher level, which were 0.90 g/L/day and 61.56%, respectively. The obtained Chlorella vulgaris biomass was rich in essential amino acids (41.80%), the essential amino acid index was as high as 89.07, and the lysine content could reach up to 4.05 g/100 g. Conclusions: This study provides a theoretical basis and guidance for using Chlorella vulgaris as an industrial fermentation platform to convert broken rice into products with high nutritional value.

Original languageEnglish (US)
Article number102
JournalBiotechnology for Biofuels and Bioproducts
Issue number1
StatePublished - Dec 2022

Bibliographical note

Funding Information:
This research was supported by the research project of State Key Laboratory of Food Science and Technology, Nanchang university (Project No. SKLF-KF-202009; SKLF-KF-201915 and SKLF-ZZB-202122), and by the Natural Science Foundation of China (Project No.21878139; No.21878237 and 22166026), and by the key project of Jiangxi Provincial Department of Science and Technology Jiangxi (20181BBF60026).

Publisher Copyright:
© 2022, The Author(s).


  • Amino acid
  • Broken rice hydrolysate
  • Chlorella vulgaris
  • Heterotrophic
  • Protein

PubMed: MeSH publication types

  • Journal Article


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