Utilization of Carbohydrates and Sugar Acids by the Rhizobia

Publisher Website
Google Scholar
Abstract
Growth and fermentation characteristics of 6 spp. of Rhizobium (2 strains of each) several strains of Bacterium radiobacter and one of Azotobacter chroococcum on a number of filter-sterilized sugars and salts of sugar acids are reported. In general, mono- and disaccharides were more readily utilized than tri- or polysaccharides and the sugar acids. Fermentation of the former resulted in the production of an acid reaction; the tri- and polysaccharides and sugar acids yielded an alkaline reaction. Bacterium radiobacter and Azotobacter chroococcum were capable of growing abundantly on practically all organic carbon sources. The method of prepn. and sterilization of the carbohydrates yielded no apparent differences in ease of availability or fermentation character. Efforts to distinguish efficient from inefficient strains of Rhizobium could not be obtained through fermentation reactions. Bacterium radiobacter may be distinguished from the Rhizobium spp. by a variety of growth and fermentation reactions, notably on Na l-mannonate and Ca 5-keto gluconate. Inability of the bacteria studied to ferment certain sugar acids is discussed in the light of the configuration of the carbohydrates. Changes in reaction and reversion in pH are also discussed.