A complete pathway for β‐alanine and β‐amino‐iso‐butyrate catabolism in Pseudomonas aeruginosa

Pseudomonas aeruginosa PAO1 was found to catabolise β‐alanine and β‐amino‐iso‐butyrate (β‐AIB) by the following pathway: (i) transamination by β‐alanine: pyruvate aminotransferase (BAPAT) to yield l‐alanine and either malonic semialdehyde or its methyl analogue, respectively; (ii) oxidative decarboxylation of the respective semialdehydes to acetyl CoA or propionyl CoA; (iii) regeneration of pyruvate from l‐alanine by the action of dl‐alanine racemase (AR) and d‐alanine dehydrogenase (DAD). Mutants defective in BAPAT or DAD failed to catabolise either β‐alanine or β‐AIB, and β‐alanine was an inducer for the entire pathway.