Growth characteristics of ultrahigh-density microalgal cultures

Research output: Contribution to journalReview articlepeer-review

25 Scopus citations


The physiological characteristics of cultures of very high cell mass {e.g. 10 g cell mass/L), termed "ultrahigh cell density cultures" is reviewed. A close relationship was found between the length of the optical path (OP) in flat-plate reactors and the optimal cell density of the culture as well as its areal (g m-2 day-1) productivity. Cell-growth inhibition (GI) unfolds as culture density surpasses a certain threshold. If it is constantly relieved, a 1.0 cm OP reactor could produce ca. 50% more than reactors with longer OP, e.g. 5 or 10 cm. This unique effect, discovered by Hu et al. [3], is explained in terms of the relationships between the frequency of the light-dark cycle (L-D cycle), cells undergo in their travel between the light and dark volumes in the reactor, and the turnover time of the photosynthetic center (PC). In long OP reactors (5 cm and above) the L-D cycle time may be orders of magnitude longer than the PC turnover time, resulting in a light regime in which the cells are exposed along the L-D cycle, to long, wasteful dark periods. In contrast, in reactors with an OP of ca. 1.0 cm, the L-D cycle frequency approaches the PC turnover time resulting in a significant reduction of the wasteful dark exposure time, thereby inducing a surge in photosynthetic efficiency. Presently, the major difficulty in mass cultivation of ultrahigh-density culture (UHDC) concerns cell growth inhibition in the culture, the exact nature of which is awaiting detailed investigation.

Original languageEnglish
Pages (from-to)349-353
Number of pages5
JournalBiotechnology and Bioprocess Engineering
Issue number6
StatePublished - 1 Jan 2003


  • Flat plate reactor
  • Growth inhibition
  • L-D cycle
  • Optical-path
  • Productivity
  • Ultrahigh density culture

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology
  • Biomedical Engineering


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