Effects of nitrogen on growth and carbohydrate formation in Porphyridium cruentum

• 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 center dot 10(8) 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.

Ämnesord

NATURVETENSKAP  -- Biologi -- Genetik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Genetics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Bioprocessteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Bioprocess Technology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Immunologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Immunology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Cellbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Cell Biology (hsv//eng)

Nyckelord

Rhodophyta

Red algae

Redfield ratio

Nitrogen-to-phosphorous ratio

RED ALGA PORPHYRIDIUM

EXTRACELLULAR POLYSACCHARIDE

CHLAMYDOMONAS-REINHARDTI

NUTRIENT LIMITATION

CULTURE-MEDIA

AERUGINEUM

STARVATION

PURPUREUM

CYCLE

PURPUREUM

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