Exopolysaccharide, Pigment And Protein Production By The Marine Microalga Chroomonas Sp. In Semicontinuous Cultures

World Journal of Microbiology & Biotechnology 20: 179–183, 2004. Ó 2004 Kluwer Academic Publishers. Printed in the Netherlands.

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Exopolysaccharide, pigment and protein production by the marine microalga Chroomonas sp. in semicontinuous cultures
´ ´ ´ ´ Jose Bermudez, Nestor Rosales, Cesar Loreto, Beltran Briceno and Ever Morales* ´ ˜ Laboratorio de Microorganismos Fotosinte´ticos,Departamento de Biologı´a, Facultad Experimental de Ciencias, La Universidad del Zulia, Maracaibo, Venezuela *Author for correspondence: Tel.:+58-261-7598107, Fax:+58-261-7541540/7598107, E-mail: everm@iamnet.com
Received 4 June 2003; accepted 29 September 2003

Keywords: Chroomonas, exopolysaccharide, HPLC, microalga, pigments, semicontinuous culture

Summary The marine microalga Chroomonas sp.isolated from Venezuela was grown in semicontinuous culture in order to study the effect of renewal rate and nutrient concentration on alloxanthin, chlorophyll a, carotenoid, carbohydrate, exopolysaccharide, protein and cell productivity. Maximal cell productivity of 8.43 ± 1.8 and 8.81 ± 2.3 · 109 cell lÀ1 dayÀ1 were achieved with renewal rates of 30 and 40%. Maximal protein and chlorophyllproductivity of 64.64 ± 2.3 and 2.72 ± 0.3 mg lÀ1 dayÀ1 were obtained with renewal rate of 20 and 30%. Biochemical composition of Chroomonas sp. was influenced by renewal rate. Nutrient concentration seems not to affect cell, protein, chlorophyll and carotenoid productivity. However, carbohydrate and exopolysaccharide productivity of 7.56 ± 0.4 and 9.57 ± 1.2 mg lÀ1 dayÀ1 were increased at 12 mM NaNO3 (P <0.05). Also, alloxanthin and chlorophyll a production analysed by HPLC, were higher between 8 and 12 mM NaNO3 at a renewal rate of 30%. Results demonstrated that a renewal rate of 30% and nutrient concentration at 8 mM NaNO3 optimize the cell, protein, carbohydrate, chlorophyll a, and exopolysaccharide productivity in semicontinuous cultures of Chroomonas. This microalga, as biological source ofcommercially valuable compounds, shows high capacity for changing its productivity and biochemical composition in semicontinuous system on the basis of nutrient concentration and the renewal rate.

Introduction Marine microalgae can be used as a source of products of high aggregated value such as pigments, exopolysaccharides, fatty acids and proteins. In addition, microalgae are used inaquaculture as protein and fatty acid source for shrimp culture (Volkman et al. 1989; Coutteau et al. 1994). However, each strain of microalga and type of product requires processes designed to increase the ´ production of enriched biomass (Fabregas et al. 1995). The productivity of microalgae in continuous and semicontinuous culture is considerably higher than conventional methods, but most of theavailable studies ´ has been done in batch culture (Fabregas et al. 1996a, b), and only a few data are available on the biochemical variability that can be generated through the manipulation of the renewal rates, nutrient concentration and other culture parameters in semicontinuous systems (Brown et al. 1993). Also, studies on the response of growth and metabolic activity of Chroomonas sp. undersemicontinuous culture are limited (Henderson & Mackinlay 1989). The possibility to manipulate culture conditions of a strain of Chroomonas, isolated from a saline pond in

Venezuela, as a source of pigments has been reported in batch cultures (Mora et al. 2002). In the present work, the marine microalga Chroomonas was evaluated in semicontinuous culture in order to study the effect of renewal rate andnutrient concentration on biomass, protein, chlorophyll, alloxanthin and exopolysaccharide productivity.

Materials and methods Organism and culture conditions The marine flagellate, cell wall-less microalga Chroomonas sp. (Cryptophyta) was isolated from a saline pond in Maracaibo, Venezuela. Cultures in triplicate were maintained in 350 ml flasks with 150 ml of sterilized seawater (salinity...