Isolation and characterization of an exopolysaccharide depolymerase fromPseudomonas marginalis HT041B

An enzyme has been isolated fromPseudomonas marginalis (a pathogen responsible for the spoilage of fruits and vegetables in storage) that degrades the exopolysaccharide (mw>2×10⁶ Da) produced by this organism. The mechanism of degradation has been determined to be a depolymerization that results from glucosidic cleavage. The product of depolymerization is a polysaccharide of ca. 2.5×10⁵ Da. The enzyme has a molecular weight of approximately 28 kDa, a pH optimum of 6.5, pI=9.1, and an apparent K_m of 1.95×10^–7±3.5×10^–8M. Native and enzyme-treated marginalan supported no or very limited growth of the bacterium respectively.Mention of brand or firm names does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.