Global stress response inPseudomonas aeruginosaupon malonate utilization
Authors: Bisht Karishma , Elmassry Moamen M. , Al Mahmud Hafij , Bhattacharjee Shubhra , Deonarine Amrika , Black Caroline , San Francisco Michael J. , Hamood Abdul N. , Wakeman Catherine A. 
Published: March 2024

Versatility in carbon source utilization assistsPseudomonas aeruginosain its adaptation to various niches. Recently, we characterized the role of malonate, an understudied carbon source, in quorum sensing regulation, antibiotic resistance, and virulence factor production inP. aeruginosa. These results indicate that global responses to malonate metabolism remain to be uncovered. We leveraged a publicly available metabolomic dataset on human airway and found malonate to be as abundant as glycerol, a common airway metabolite and carbon source forP. aeruginosa. Here, we explored and compared adaptations ofP. aeruginosaUCBPP-PA14 (PA14) in response to malonate or glycerol as a sole carbon source using transcriptomics and phenotypic assays. Malonate utilization activated glyoxylate and methylcitrate cycles and induced several stress responses, including oxidative, anaerobic, and metal stress responses associated with increases in intracellular aluminum and strontium. Some induced genes were required for optimal growth ofP. aeruginosain malonate. To assess the conservation of malonate-associated responses amongP. aeruginosastrains, we compared our findings in strain PA14 with other lab strains and cystic fibrosis isolates ofP. aeruginosa. Most strains grew on malonate as a sole carbon source as efficiently as or better than glycerol. While not all responses to malonate were conserved among strains, formation of biomineralized biofilm-like aggregates, increased tolerance to kanamycin, and increased susceptibility to norfloxacin were the most frequently observed phenotypes. Our findings reveal global remodeling ofP. aeruginosagene expression during its growth on malonate as a sole carbon source that is accompanied by several important phenotypic changes. These findings add to accumulating literature highlighting the role of different carbon sources in the physiology ofP. aeruginosaand its niche adaptation.

Importance

Pseudomonas aeruginosais a notorious pathogen that causes local and systemic infections in immunocompromised individuals. Different carbon sources can uniquely modulate metabolic and virulence pathways inP. aeruginosa, highlighting the importance of the environment that the pathogen occupies. In this work, we used a combination of transcriptomic analysis and phenotypic assays to determine how malonate utilization impactsP. aeruginosa,as recent evidence indicates this carbon source may be relevant to certain niches associated within the human host. We found that malonate utilization can induce global stress responses, alter metabolic circuits, and influence various phenotypes ofP. aeruginosathat could influence host colonization. Investigating the metabolism of malonate provides insight intoP. aeruginosaadaptations to specific niches where this substrate is abundant, and how it can be leveraged in the development of much-needed antimicrobial agents or identification of new therapeutic targets of this difficult-to-eradicate pathogen.