Cloning, expression and characterization of a beta-agarase gene from a marine bacterium, Pseudomonas sp. SK38

A gene (pagA) encoding beta-agarase from Pseudomonas sp. SK38 was cloned and expressed in Escherichia coli. The structural gene consists of 1011 bp encoding 337 amino acids with a predicted molecular weight of 37326 and has a signal peptide of 18 amino acids. The deduced amino acid sequence showed 57% and 58% homology to beta-agarase from Pseudoalteromonas atalntica and Aeromonas sp., respectively. The recombinant enzyme was purified and biochemically characterized. The enzyme had maximum activity at pH 9 and 30 degrees C. It was stable at pHs from 8 to 9 and below 37 degrees C.