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RELEASE OF CARBOHYDRATES AND PROTEINS BY A SUBTROPICAL STRAIN OF RAPHIDIOPSIS BROOKII (CYANOBACTERIA) ABLE TO PRODUCE SAXITOXIN AT THREE NITRATE CONCENTRATIONS1
Article first published online: 18 MAY 2009
© 2009 Phycological Society of America
Journal of Phycology
Volume 45, Issue 3, pages 585–591, June 2009
How to Cite
Yunes, J. S., De La Rocha, S., Giroldo, D., Silveira, S. B. d., Comin, R., Bicho, M. d. S., Melcher, S. S., Sant’anna, C. L. and Vieira, A. A. H. (2009), RELEASE OF CARBOHYDRATES AND PROTEINS BY A SUBTROPICAL STRAIN OF RAPHIDIOPSIS BROOKII (CYANOBACTERIA) ABLE TO PRODUCE SAXITOXIN AT THREE NITRATE CONCENTRATIONS. Journal of Phycology, 45: 585–591. doi: 10.1111/j.1529-8817.2009.00673.x
Received 22 June 2008. Accepted 28 January 2009.
- Issue published online: 5 JUN 2009
- Article first published online: 18 MAY 2009
Raphidiopsis brookii P. J. Hill (cyanobacteria) was isolated from a small subtropical eutrophic pond (Biguá Pond) located in the grounds of Rio Grande University in the extreme south of Brazil, following a toxic bloom of this species. Growth, saxitoxin production, and release of carbohydrates and protein were monitored at three sodium nitrate concentrations (500, 1,000, and 1,500 μM), from inoculation up to the stationary growth phase. Growth was monitored by determining the biovolume, chl content, and trichome count. Growth was better described in terms of biovolume and chl measurements, because trichome fragmentation was observed to increase at the stationary growth phase. Carbohydrates and proteins were released in small amounts during most of the experiment, with a significant increase during the stationary phase. Extracellular polysaccharides were essentially composed of glucose, galactose, N-acetyl-glucosamine, mannose, xylose, rhamnose, arabinose, and fucose. The relative proportions of these units showed no significant variation during growth. Small quantities of extracellular free carbohydrates were also detected, and only fucose was released in significant amounts at the lowest nitrate concentration (500 μM). R. brookii produced both saxitoxin and dc-saxitoxin, the former at four times the rate of the latter. This was the first study demonstrating saxitoxin production and the release of both carbohydrate and protein by R. brookii.