Long-Term Anaerobic Survival of the Opportunistic Pathogen Pseudomonas aeruginosa via Pyruvate Fermentation

Abstract

Denitrification and arginine fermentation are central metabolic processes performed by the opportunistic pathogen Pseudomonas aeruginosa during biofilm formation and infection of lungs of patients with cystic fibrosis. Genome-wide searches for additional components of the anaerobic metabolism identified potential genes for pyruvate-metabolizing NADH-dependent lactate dehydrogenase (ldhA), phosphotransacetylase (pta), and acetate kinase (ackA). While pyruvate fermentation alone does not sustain significant anaerobic growth of P. aeruginosa, it provides the bacterium with the metabolic capacity for long-term survival of up to 18 days. Detected conversion of pyruvate to lactate and acetate is dependent on the presence of intact ldhA and ackA-pta loci, respectively. DNA microarray studies in combination with reporter gene fusion analysis and enzyme activity measurements demonstrated the anr-and ihfA-dependent anaerobic induction of the ackA-pta promoter. Potential Anr and integration host factor binding sites were localized. Pyruvate-dependent anaerobic long-term survival was found to be significantly reduced in anr and ihfA mutants. No obvious ldhA regulation by oxygen tension was observed. Pyruvate fermentation is pH dependent. Nitrate respiration abolished pyruvate fermentation, while arginine fermentation occurs independently of pyruvate utilization.

Genome and proteome of long-chain alkane degrading Geobacillus thermodenitrificans NG80-2 isolated from a deep-subsurface oil reservoir

“…Fermentation is an important mechanism for anaerobic growth of bacteria in the absence of alternative electron acceptors (22), and several genes of typical pyruvate fermentation pathways were found such as pta (GT3361), ackA (GT2688), ldh (GT0487), and buk (GT2309). The por genes (GT1718-GT1717), which encode pyruvate-ferredoxin oxidoreductase and are commonly present in anaerobic bacteria (23), were also found.…”

Anaerobic Survival ofPseudomonas aeruginosaby Pyruvate Fermentation Requires an Usp-Type Stress Protein

“…Moreover, arginine sustains moderate anaerobic growth via fermentation (44). Recently, we have shown that pyruvate-one of the most abundant metabolites in all cells-allows anaerobic long-term survival of P. aeruginosa (13). However, in contrast to denitrification and arginine fermentation, pyruvate fermentation does not sustain anaerobic growth.…”

“…We identified three enzymes essential for pyruvate fermentation: phosphotransacetylase (Pta), acetate kinase (AckA), and a lactate dehydrogenase (LdhA). The operon encoding Pta and AckA is induced in response to oxygen limitation in dependence of the anaerobic regulatory protein Anr (13). The ackA-pta locus in Escherichia coli is induced in response to starvation during aerobic conditions (31).…”

Endogenous Phenazine Antibiotics Promote Anaerobic Survival of Pseudomonas aeruginosa via Extracellular Electron Transfer

“…Throughout the incubation period, we continuously recorded the anodic (oxidation) current as well as the charge transferred due to the oxidation of an electrochemically active component(s) at the working electrode. Periodically, we sampled to measure viability by means of counting the number of CFU on LB agar (11). We observed that the ⌬phz mutant maintained a constant viable cell number at the original 10 9 CFU/ml over 7 days, characteristic of survival but not growth (Fig.…”