Characterization of the agarase system of a multiple carbohydrate degrading marine bacterium

A marine bacterium strain 2-40 (2-40) degraded numerous complex carbohydrates, such as agar, chitin and alginate. It may play an important role in altering carbon fluxes in marine environments. End-product analyses revealed that 2-40 synthesized an agarase system that consisted of at least three enzymes, beta-agarase I, beta-agarase II and alpha-agarase, which acted in concert to degrade polymeric agar to D-galactose and 3,6-anhydro-L-galactose. The agarase system was shown to be both cell envelope-associated and extracellular, with the relative concentrations depending on the growth phase. The principal depolymerase, a beta-agarase I, hydrolysed agar to both neoagarotetrose and neoagarobiose, as identified by thin layer chromatography. This agarase had a mass of 98 kD and a Pi of 4.3. The agarase system was repressed by D-glucose and D-galactose and induced by agar, agarose, neoagarobiose, neoagarotetrose and neoagarohexose.