Aldohexuronic Acid Catabolism by a Soil Aeromonas

摘要: Bacteria which utilize mannuronic acid as an energy source were isolated from nature. One of the organisms, identified a member genus Aeromonas, used glucuronate, galacturonate, and mannuronate sole carbon energy. Glucuronate- galacturonate-grown resting cells oxidized both glucuronate galacturonate rapidly, but slowly. Mannuronate-grown all three with rate utilization somewhat lower. Cell-free extracts glucuronate-, galacturonate-, mannuronate-grown Aeromonas C11-2B contained isomerases, fructuronate, tagaturonate, reductases, mannonate altronate dehydratases, exception glucuronate-grown lacked dehydratase. Thus, pathway for catabolism was identical to Escherichia coli. Glucuronate isomerized d-fructuronate d-tagaturonate then reduced by nicotinamide adenine dinucleotide d-mannonate d-altronate, respectively. The hexonic acids dehydrated 2-keto-3-deoxy gluconate phosphorylated adenosine triphosphate 2-keto-3-deoxy-6-phospho gluconate. latter cleaved pyruvate glyceraldehyde-3-phosphate. Mannuronate directly phosphate-linked oxidoreductase. d-Mannonate further broken down in pathway. reducing enzyme, name d-mannonate:nicotinamide (phosphate) oxidoreductase (d-mannuronate-forming) proposed, shown be distinct mannoate oxidoreductases. This is first report bacterial reduces aldohexuronic acid. enzyme should prove useful analytical tool determining presence other uronic acids.