Abstract

JONTE, Lorena; ROSALES-LOAIZA, Néstor; BERMUDEZ-GONZALEZ, José  and  MORALES, Ever. Urea fed-batch cultures of the cyanobacterium Phormidium sp. as a function of the salinity and age of cultures. Rev. colomb. biotecnol [online]. 2013, vol.15, n.2, pp.38-46. ISSN 0123-3475.  https://doi.org/10.15446/rev.colomb.biote.v15n2.28125.

Fed-batch system efficiency versus batch cultures was compared in relation to nitrogen concentration, adding 0,2mM urea at the end of the exponential phase, during 21 days. Cultures were carried out in 1500 mL to 1.5 and 3.5 UPS of salinity, enriched with Algal medium 8mM NaNO₃, 238 mol q m^-2 s^-1, constant aeration, photoperiod 12:12 h. and 29 ±3°C. Phormidium sp. is able to hydrolyze urea; showing a total assimilation of 65±7.07%, with the highest (p< 0.05) chlorophyll a, phycocyanin and protein production of 20.26 ± 1.24, 203.47 ± 12.83 and 707.87 ± 28.47 µg mL^-1 in the fed-batch cultures. On the other hand, pigment production varies in time, regardless salinity and culture system. Proteins and total carbohydrate production were directly proportional to the age of cultures, with maximum values of 612.74 ± 5.41 µg mL^-1 and 8.96 ± 0.08 mg mL^-1, respectively. Lipid and EPS were influenced (p< 0.05) by salinity, showing maximum of lipids at 15 UPS with 12.22±2.91 µg mL^-1, and EPS at 15 and 35 UPS with 2.00 ± 0.26 and 2.03 ± 0.15 mg mL^-1. These results determine that Phormidium sp. cultures fed with urea, to salinities of 15-35 UPS, represent an economic alternative for chlorophyll a, phycocyanin and protein production, with an increase of 31.04, 40.72 and 31.94% respectively in comparison with non-fed cultures.

Keywords : chlorophyll; phycocyanin; proteins; cyanobacterium; urea.

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