Biodegradation of the sulphated polysaccharide of Porphyridium by soil bacteria

In the absence of carbohydrolases capable of degrading the complex cell wall polysacchadde of red microalgae, its structure and composition have so far been studied solely by means of conventional chemical methods. Recently, a mixture of soil bacteria was isolated that can grow on and specifically degrade the polysaccharide of Porphyridium sp. In the present work this enzymatic activity was used for further study of this cell wall polysaccharide. Upon charge separation, the native and degraded polysaccharides showed similar patterns, except with regard to protein distribution. In the polysaccharide degraded with bacterial enzymes, protein appeared in the fraction eluted with water, whereas in the native polysaccharide it appeared in the fraction cluted with urea. By size separation of the polysaccharide degraded with bacterial enzymes, a single peak of 5-6 × 10⁶ daltons was obtained as compared with a 7 × 10⁶ daltons peak in the native polysaccharide. Although the main product of enzymatic bacterial activity had a relatively high molecular mass, its viscosity was very low compared with that of the native polysaccharide. The results indicate that the bacterial enzymes degraded the polysaccharide by cleaving proteins from the polysaccharide.