Catabolism of d -Glucaric Acid to α-Ketoglutarate in Bacillus megaterium

Abstract

Crude cell-free extracts of D-glucarate-grown cells of Bacillus megaterium converted D-glucarate to a-keto-fl-deoxy-D-glucarate (KDG). Charcoal-treated cell-free extracts or partially purified enzyme preparations converted KDG to an intermediate which was isolated and identified as 2,5-diketoadipate (DKA). This compound was synthesized, and the cell-free extracts of D-glucarate grown cells were found to catalyze the reduction of nicotinamide adenine dirrucleotide (NAD) in its presence. In the absence of NAD, the same enzyme preparation catalyzed the decarboxylation of the DKA to a-ketoglutarate semialdehyde (KGS), whereas in the presence of NAD the KGS was subsequently oxidized to a-ketoglutarate by a-ketoglutarate semialdehyde dehydrogenase. Since galactarate-grown B. megaterium contains a galactarate dehydrase forming KDG, the complete pathway for the metabolism of D-glucarate or galactarate to a-ketoglutarate and CO2 is now known in a gram-positive bacterium.

A link between gut community metabolism and pathogenesis: molecular hydrogen-stimulated glucarate catabolism aids Salmonella virulence

“…However, many enzymes that are synthesized and active during host infection exhibit little or no effects in virulence models [13,14]. Researchers have suggested that D-glucarate can serve as a growth substrate for a variety of microorganisms including Escherichia coli and related enteric bacteria [15,16]. In a study identifying some of the genes affecting glucarate utilization in E. coli strain K12, Roberton et al [17] noted the availability of glucarate in humans at levels near the K m of whole E. coli cells for the organic acid and he subsequently speculated that pathogenic E. coli strains may benefit by using host D-glucarate as an alternative carbon source.…”