Research Article

Central European Journal of Biology

, Volume 9, Issue 2, pp 156-162

First online:

Effects of nitrogen on growth and carbohydrate formation in Porphyridium cruentum

  • Ali RazaghiAffiliated withBiological and Environmental Sciences, University of Gothenburg
  • , Anna GodheAffiliated withBiological and Environmental Sciences, University of Gothenburg
  • , Eva AlbersAffiliated withChemical and Biological Engineering — Industrial Biotechnology, Chalmers University of Technology Email author 

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The microalga Porphyridium cruentum (Rhodophyta) has several industrial and pharmaceutical uses, especially for its polysaccharide production. This study aimed to investigate the influence of nitrogen levels as reflected by altered N:P ratios on the production and content of biomass and carbohydrate. N:P molar ratios were altered in batch cultures to range from 1.6 to 50 using the Redfield ratio of 1:16 as reference. Algal growth (estimated as final cell number, biomass concentration and maximum specific growth rate) was negatively affected at low N:P ratios. The optimal N:P ratio for growth was identified at 35–50, with specific growth rates of 0.19 day−1 and maximum cell concentrations of 59·108 cells L−1 and 1.2 g dry weight of biomass L−1. In addition, variation in cell size was seen. Cells with larger diameters were at higher N:P ratios and smaller cells at lower ratios. The cellular carbohydrate content increased under reduced nitrogen availability. However, because accumulation was moderate at the lowest N:P ratio, 0.4 g per g dry weight biomass compared to 0.24 at the Redfield ratio of 16:1, conditions for increased total carbohydrate formation were identified at the N:P ratios optimal for growth. Additionally, carbohydrates were largely accumulated in late exponential to stationary phase.


Rhodophyta Red algae Redfield ratio Nitrogen-to-phosphorous ratio