Characterization of Agarose Product from Agar Using DMSO

Gels are widely used for separation of biological molecules by techniques such as gel filtration, ionexchange chromatography, as well as for immobilization of biocatalysts (Armisen 1997; Fuji et al. 2000; Millan et al. 2002). Agarose, one of the neutral gelling substances is widely used not only in the field of biotechnology but also in many industries. Agarose is a linear, neutral marine polysaccharide consisting of alternating (1,3)-linked-β-D-galactopyranose and 1,4-linked-3, 6-anhydro-α-L-galactopyranose that is separated from agar by removing agaropectine. The polymer exists as a random coil in dilute or hot solutions but undergoes conformational transitions to form ordered helices in the solid state (Guiseley 1970). The large pore size, low electroendosmosis and the strength of the matrix of agarose have advantages over other media such as polyacrylamide in many applications. Due to its unique nature, agarose is applied to the biotechnology area as a key element in powerful techniques such as gene mapping and for special gel electrophoresis methods where a non-ionic solid is required (Abbot 1990). With the increment of biotechnological applications, agarose has become the highest priced seaweed product sharing 0.2% of the phycocolloid market (Critchley 1997). Agarose is manufactured by removing the ionic fractions of agar under highly controlled conditions designed to minimize variation (Radmer 1996). The traditional separation of agarose mainly depends on DEAEcellulose, a weaker anion exchanger. The methods involved in separation of agarose are highly complex and require intensive separation techniques in order to minimize lot-to-lot variation. The unit value of some of these products can be impressive, ranging beyond 25,000 $/kg (Radmer 1996). The possibility of agarose production from agar by extraction, batchwise ion exchange has been investigated. The purification efficiency and adsorption capacity of agarose obtained from the above methods are highly controversial. Therefore, finding alternative simple and productive method for good quality agarose is highly desired. The aim of this study is to investigate preparation of high quality agarose from agar by simple separation techniques. Dimethyl sulfoxide (DMSO), a unique solvent, was used to separate agarose from agar by removing agaropectine and characterizations of the agarose prepared in this method were examined. Algae Volume 20(1): 61-67, 2005