Fixing N2 into cyanophycin: continuous cultivation of Nostoc sp. PCC 7120

Giulia Trentin, Francesca Piazza, Marta Carletti, Boris Zorin, Inna Khozin-Goldberg, Alberto Bertucco, Eleonora Sforza

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Abstract: Two diazotrophic cyanobacteria (Anabaena cylindrica PCC 7122 and Nostoc sp. PCC 7120) were cultivated to produce cyanophycin, a nitrogen reserve compound, under nitrogen fixing conditions. In preliminary continuous experiments, Nostoc sp. was shown to be more efficient, accumulating a higher amount of cyanophycin and showing a greater capability to fix atmospheric nitrogen in the biomass (67 mgN d−1 of fixed nitrogen per liter of culture). The operating conditions were then optimized to maximize the cyanophycin productivity: the effect of incident light intensity, residence time and nitrogen availability were investigated. Nitrogen availability and/or pH played a major role with respect to biomass production, whereas phosphorus limitation was the main variable to maximize cyanophycin accumulation. In this way, it was possible to achieve a stable and continuous production of cyanophycin (CGP) under diazotrophic conditions, obtaining a maximum cyanophycin productivity of 15 mgCGP L−1 d−1. Key points: • Diazotrophic cyanobacteria produce stable amount of cyanophycin in continuous PBR. • Nostoc sp. proved to be more efficient in producing cyanophycin than Anabaena sp. • P deprivation is the major variable to increase cyanophycin productivity in continuous.

Original languageEnglish
Pages (from-to)97-110
Number of pages14
JournalApplied Microbiology and Biotechnology
Issue number1
StatePublished - 1 Jan 2023


  • Arginine
  • Aspartic acid
  • CGP
  • Diazotrophic
  • Polypeptide

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Biotechnology


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