Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales) in function to irradiance. Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 ±2ºC and 35‰. Maximum values of protein, carbohydrates and lipids, of 530.19 ±11.16, 408.94 ±4.27 and 56.20 ±1.17 µg ml<span name="style_sup">-1</span>, respectively, were achieved at 78 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>. Pigments, analyzed by HPLC, showed maximum values at 78 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span> for chlorophyll a with 7.72 ±0.16 µg ml<span name="style_sup">-1</span>, and at 234 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span> for ß-carotene and zeaxanthin with 0.70 ±0.01 and 0.67 ±0.05 µg ml<span name="style_sup">-1</span>. Chlorophyll a:ß-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>; whereas ß-carotene:zeaxanthin ratio showed no changes between 78 and 156 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>, around 1.21, and decreased at 234 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>, to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>, with 406.13 ±21.74 x106 cell ml<span name="style_sup">-1</span> and 1.49 ±0.11 mg ml<span name="style_sup">-1</span>, respectively. Exopolysaccharide production was stable between 156 y 234 µmol q m<span name="style_sup">-2</span> s<span name="style_sup">-1</span>, around 110 µg ml<span name="style_sup">-1</span>. This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites. Rev. Biol. Trop. 56 (2): 421-429. Epub 2008 June 30.. This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites. Rev. Biol. Trop. 56 (2): 421-429. Epub 2008 June 30.

Cianobacteria; composición bioquímica; irradiancia; Synechococcus