Intracellular Alginate-oligosaccharide Degrading Enzyme Activity that is Incapable of Degrading Intact Sodium Alginate from a Marine Bacterium <i>Alteromonas</i> sp.

Abstract

Intracellular homo-and hetero-polymeric blocks degrading enzyme activity incapable of degrading intact sodium alginate was detected in Alteromonas sp. strain H-4. The enzyme activity for polyM and MG blocks was highest during the late log phase of the bacterium and was not induced by the addition of sodium alginate to the culture medium. The activity for MG random block was as high as that for polyM, but that for polyG block was half and that for sodium alginate was one fifth. At least 4 kinds of enzyme activities, a polyM specific, a MG-polyM specific, and two kinds of polyG specific enzymes, were detected from the crude intracellular fraction, but a trace spot for sodium alginate. Analysis of reaction products using a partially purified preparation of the enzyme indicated that the enzyme generated a saturated diuronate and an unsaturated polyuronide from polyM block. These results suggest that the intracellular enzymes can degrade only oligosaccharides generated from high molecular alginate by the extracellular alginate lyase and may have an important role in the alginate metabolism of the bacterium.