Regulation of Acinetobacter baumannii biofilm formation by c-di-GMP signaling

Project Information

AB-Biofilm

Grant agreement ID: 101064174

DOI

10.3030/101064174

Project closed

EC signature date 5 August 2022

Start date 1 March 2023

End date 28 February 2025

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 230 774,40

Coordinated by

KOBENHAVNS UNIVERSITET
Denmark

Periodic Reporting for period 1 - AB-Biofilm (Regulation of Acinetobacter baumannii biofilm formation by c-di-GMP signaling)

Reporting period: 2023-03-01 to 2025-02-28

Summary of the context and overall objectives of the project

Drug-resistant bacterial infections pose a major and growing threat to global public health, with estimates suggesting that antimicrobial resistance (AMR) could cause up to 10 million deaths annually by 2050 without effective action. One particularly challenging pathogen is Acinetobacter baumannii, a bacterium known for its ability to survive in harsh environments, rapidly develop antibiotic resistance, and form persistent biofilms. Biofilms are protective bacterial communities that shield cells from antibiotics and host defenses, making infections difficult to eradicate and leading to high rates of morbidity and mortality.
This project aimed to investigate the internal signaling systems that regulate biofilm formation and stress adaptation in A. baumannii, focusing on cyclic-di-GMP (c-di-GMP), a key bacterial second messenger. By systematically studying how changes in c-di-GMP levels affect bacterial behaviors, the project sought to identify new molecular targets that could be exploited to prevent biofilm formation and combat persistent infections. The knowledge gained is expected to contribute to developing novel therapeutic strategies, improving patient outcomes, and addressing the urgent societal need to tackle antimicrobial resistance. Given the projected scale of the AMR crisis, these findings are timely and of high strategic importance for public health.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the project, a collection of A. baumannii mutants was generated by individually deleting eleven genes predicted to be involved in c-di-GMP metabolism. Each mutant was validated and subjected to phenotypic assays assessing growth, surface motility, biofilm formation, desiccation tolerance, and antibiotic susceptibility. These traits are critical for understanding the bacteria’s ability to establish infections, resist antibiotic treatment, and survive on hospital surfaces. By linking genetic changes to infection potential and persistence mechanisms, the project directly addresses major challenges in combating A. baumannii in healthcare settings. To better understand how genetic changes affect bacterial behavior, I analyzed the complete set of proteins produced by the bacteria under different conditions, comparing normal strains with genetically modified ones grown both freely and in biofilm communities. Integration of phenotypic, proteomic, and signaling data revealed multiple pathways influenced by c-di-GMP, contributing to biofilm matrix production, membrane remodeling, and stress responses.
Collaborative work was initiated to quantify biofilm polysaccharides in selected mutants, supporting the molecular findings with biochemical validation. Overall, the project successfully built a systems-level understanding of how intracellular signaling networks control clinically relevant traits in A. baumannii, opening new avenues for therapeutic intervention.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

This project pushed the boundaries of current knowledge by systematically linking genetic alterations in c-di-GMP metabolism to complex phenotypic and proteomic changes in a major human pathogen. Previous studies largely focused on individual factors; this project instead provided a holistic, high-resolution map of regulatory impacts in A. baumannii.
The results identify new candidate pathways and regulatory proteins that could be targeted to disrupt biofilm formation and enhance antibiotic efficacy. To translate these findings into practical applications, further research will be needed to characterize the identified targets mechanistically, validate them in infection models, and explore potential collaborations with industry partners for therapeutic development. The work also highlights the importance of systems biology approaches for understanding bacterial resilience, with broader relevance across microbiology and infectious disease research.

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