Bacteria Decomposing Alginic Acid

Alginic acid is a complex carbohydrate belonging to the group of polyuronides; these yield, on hydrolysis with mineral acids, sugar acids, known as uronic acids, or mixtures of these acids with hexose or pentose sugars; purified alginic acid yields on hydrolysis only mannuronic acid. Alginic acid occurs abun-dantly in various marine algae, to the extent of 20 to 30 per cent of the total algal material. Although algal residues serve as food for a great variety of animals living both in water and on land, a large part of the residues are decomposed in nature by the action of microorganisms. The processes of their decomposition, espe-cially the fate of the alginic acid complex, still remain to be determined. In the course of a study of the decomposition of marine algal material, a number of bacteria capable of decomposing alginic acid were isolated from sea water, from phytoplankton and from the sea bottom. The decomposition of this compound was also studied in the case of land soils and several bacteria isolated; these differed, however, in certain of their physiological characteristics from the marine bacteria. It is important to add here that bac-teria are the all-important agents concerned in the decomposition of alginic acid in nature. Even in soil, which is such a favorable medium for the growth of numerous fungi and actinomyces, the decomposition was carried out almost entirely by bacteria. The most active cellulose- and hemicellulose-decomposing fungi