Editorial: In commemoration of the bicentennial of the birth of Louis Pasteur

The history of microbiology has known many ground-breaking discoveries that have significantly influenced not only the development of the discipline itself, but science in general. There are also many fathers of such epochal discoveries, whose memory we, their heirs and continuators, are obliged to cherish. Although the list of eminent microbiologists and their outstanding achievements has no fixed hierarchy, the names of Leeuwenhoek, Pasteur, or Koch will always be among the most famous and recognizable worldwide.

The name of Pasteur probably enjoys the greatest recognition, not only in the scientific community, but also among the general public. It is perhaps most strongly associated with the genesis of microbiology and its paternity. It is to Pasteur that the name of “father of microbiology” has clung most tenaciously and has perpetuated across all fields of science and in common culture.

The year 2022 marked the bicentennial anniversary of the birth of Louis Pasteur, and that milestone was commemorated through a series of events across the world. One very special fete was an international scientific conference under the motto “The last word belongs to microbes,” paraphrasing the famous words of Pasteur: “C'est les microbes qui auront le dernier mot,” organized on November 29 and 30, 2022 in Warsaw, Poland. The conference gathered world’s leading experts and scholars specializing in different fields of microbiology (https://pasteur2022.medicaexpert.pl/). Among keynote speakers were distinguished scientists from the Pasteur Institute, which stands as a living testament to the fruitful life and immense legacy of Louis Pasteur.

This Special Issue of FEMS Microbiology Reviews has been conceived as the closing finale of the 2022 celebrations of the 200th anniversary of the birth of the “father of microbiology.” It also lends a “post scriptum” to the aforesaid conference, with many of the contributors to this special issue being distinguished guests at that meeting who delivered invited, plenary lectures.

As it was the intention of the organizers of the conference, the purpose of this issue was to provide a wide range of topics covering various aspects of microbiology, including microbial taxonomy, ecology, genetics, and pathogenesis.

The collection of review articles accommodated in this issue represents an exceptional panorama of some major research problems in today’s microbiology, emphasizing both the versatility and capacity of the discipline and its importance for the development of global science and addressing the most pressing scientific challenges of our time.

The issue opens with an article paying tribute to Pasteur not only as a genuine scientist, who bequeathed remarkable legacy of pioneering concepts and fundamental discoveries, but also as a man whose personal life, character, beliefs, and values epitomize the canonical ethos of science that have continued to inspire and motivate people of all scientific professions and beyond. The article by Raichvarg and Jagielski (2024) is far from a typical biographical text and is rather a sociological study of a fascinating phenomenon of a man who achieved greatness not so much through a sparkle of genius as through an unwavering axiology, inexhaustible curiosity, tenacity, and determination in his work.

Tuberculosis (TB) persists as the leading cause of death due to a single infectious agent. Every year, TB affects 10 million people worldwide, claiming more than a million lives. Despite vast efforts and decades of progress in research and management, the goal of the Global End TB Strategy, adopted by the World Health Organization, to eliminate TB as a global epidemic, is still drifting away from our grasp. An important way to discovering new advances and novel therapies for TB leads through gaining an in-depth insight, also in the evolutionary context, the genetic makeup of the pathogen, at both individual and population levels. The review by Orgeur et al. (2024) presents new perspectives on the evolution of mycobacteria, outlining key milestones in their development, with an emphasis on genomic events that likely contributed to the emergence and dominance of the Mycobacterium tuberculosis complex (MTBC). The authors also examine recent studies on various MTBC lineages, highlighting their unique characteristics and differences, particularly in terms of host preferences and geographic distribution.

On how investigating the genetic structure of MTBC strain populations has enhanced our understanding of TB epidemiology, and improved TB surveillance and control strategies is the review by Couvin et al. (2025). A comprehensive and critical overview of the state-of-the-art genotyping methods and bioinformatic pipelines, essential for performing molecular epidemiology studies, is given, with a special focus on the potential of the analytical tools currently available, to address critical issues, such as insufficient strain profiling, limited access to drug resistance data, and pitfalls in tracking the dynamics and transmission patterns of TB, especially in regions endemic for the disease.

Leprosy is a second major mycobacterial infection of humans. Like TB, it is a chronic, granulomatous disease that has plagued mankind for centuries. However, leprosy differs from TB in many respects, including epidemiology, clinical features, and biology of the etiological agent. Although the prevalence of leprosy has declined drastically over the last four decades, there are still endemic pockets of infection in certain parts of the world. The disease is rarely fatal, yet it may produce serious disability due to peripheral neuropathy. There have been several attempts to assess the genetic variability of Mycobacterium leprae, the major causative agent of leprosy. Whole-genome sequencing of a large collection of M. leprae strains in recent years has allowed the elaboration of advanced genotyping tools for the molecular epidemiology of leprosy. Distinct M. leprae genotypes and their unique genomic markers have been identified upon comparative genomic studies. The review by Ansari et al. (2025) recapitulates the progress that has been made in M. leprae genomics, with a prime focus on the development of genotyping schemes.

A separate place in this issue is given to the Pseudomonas putida group, which are cosmopolitan bacteria, standing out for their remarkable metabolic versatility, which translates into a wide range of ecological roles, but also affects clinical relevance, and biotechnological potential. In their review, Udaondo et al. (2024) demonstrate how methods of advanced population genomics can be exploited to expand our knowledge of key P. putida group species, especially in terms of their genetic diversity, ecological functions, and potential industrial applications.

The next two reviews are devoted to fungal pathogens. Both papers raise the issue of pathogenicity in fungi. In doing so, they do not concentrate on a specific fungal pathogen, but address the problem more generally, using several pathogenic fungi as examples. First, de Hoog et al. (2024) discuss the life strategies of fungal primary and opportunistic pathogens. Fundamental differences between primary pathogenicity and opportunism are pointed out, with the ecological and evolutionary implications for the host–pathogen relationship outlined. Second, Kozubowski and Berman (2025) explain how the phenotypic heterogeneity impacts the pathogenicity and drug responses in human fungal pathogens. The review has a three-pronged approach. It first synthetizes the current knowledge with regard to the sources and mechanisms of phenotypic heterogeneity in fungi. Then, aspects of phenotypic heterogeneity that are clinically relevant are highlighted. In the final part of the review, the authors address unresolved questions and possible future directions for research on phenotypic heterogeneity in fungal pathogenesis.

The editors of this Special Issue would like to thank all authors for their valued contributions as well as the reviewers who provided constructive comments and insightful suggestions.

We are greatly indebted to Professor Karin Sauer, co-Editor-in-Chief of the FEMS Microbiology Reviews, who expressed much interest for the early idea of launching this issue and was very supportive toward this endeavor throughout its development. We would also like to acknowledge Ms. Jennifer Norman, the Editorial Administrator of the journal, for her excellent assistance over the entire production process.

We hope that the articles contained in this Special Issue will help readers make their minds better prepared for discoveries or any scientific challenges that may come their way. As Pasteur used to say: In the field of observation, chance favors only the prepared mind (Dans les champs de l'observation, le hasard ne favorise que les esprits préparés) (Vallery-Radot 1939).

Conflict of interest

None declared.