The Pseudomonas aeruginosa Complement of Lactate Dehydrogenases Enables Use of d - and l -Lactate and Metabolic Cross-Feeding

Abstract

Lactate is thought to serve as a carbon and energy source during chronic infections. Sites of bacterial colonization can contain two enantiomers of lactate: the l -form, generally produced by the host, and the d -form, which is usually produced by bacteria, including the pulmonary pathogen Pseudomonas aeruginosa . Here, we characterize P. aeruginosa ’s set of four enzymes that it can use to interconvert pyruvate and lactate, the functions of which depend on the availability of oxygen and specific enantiomers of lactate. We also show that anaerobic pyruvate fermentation triggers production of the aerobic d -lactate dehydrogenase in both liquid cultures and biofilms, thereby enabling metabolic cross-feeding of lactate over time and space between subpopulations of cells. These metabolic pathways might contribute to P. aeruginosa growth and survival in the lung.