High-level expression of a neoagarobiose-producing beta-agarase gene from Agarivorans sp. JAMB-A11 in Bacillus subtilis and enzymic properties of the recombinant enzyme

The structural gene for a neoagarobiose-producing beta-agarase of an Agarivorans isolate was expressed in Bacillus subtilis. High-level production of the recombinant Enzyme was achieved corresponding to a level of 1.9 x 10(4) units/l of the culture broth. The efficiency of the production is thus 30-fold greater than that of the original strain. The recombinant Enzyme (RagaA11) had a molecular mass of 105 kDa and a specific activity of 371 units/mg. The optimal pH and temperature of the Enzyme were 7.5-8.0 and 40 degrees C respectively. The Enzyme is an endo-type beta-agarase hydrolysing not only Agarose, but also neoagarotetraose, to yield neoagarobiose as the final main product, representing approx. 90 mol% of total products. RagaA11 would be useful for industrial production of neoagarobiose.