The pathogenic Flavobacteriaceae: recent advances in the understanding of physiology, genetics, and virulence

The family Flavobacteriaceae is the largest family of the Bacteroidetes phylum, including a rather complex group of halophilic as well as psychrophilic species, and its members thrive in a wide variety of habitats. These Gram-negative, rod-shaped, aerobic bacteria are commonly referred to as flavobacteria. The taxonomy of members of the family Flavobacteriaceae is considered controversial, with many organisms that have been renamed and uprooted several times since the first classification. With the recent advances in molecular biology and biotechnology applied to taxonomy, several novel genera within the family Flavobacteriaceae (e.g., Capnocytophaga, and Tenacibaculum) have emerged, which a vast increase in the number of described genera within the Flavobacteriaceae from 10 to more than 150 in the past two decades. Members of the family Flavobactereaceae are well known for their ubiquitous distribution in terrestrial and aquatic environments, metabolic diversity, and in some cases pathogenicity in animals, particularly different fish species of commercial interest.

The infections caused by flavobacteria are severe and difficult to be prevented, treated, and controlled. Despite the recent advances in molecular biology applied to different Flavobacteriaceae family members, the pathogenesis mechanisms are still poorly understood due to the lack of efficient microbiological and molecular manipulation methods. Recent interesting studies have highlighted new virulence mechanisms of pathogenic species belonging to Flavobacteriaceae: The Type IX secretion system (T9SS), which is a common but apparently confined to members of phylum Bacteroidetes, is involved in the secretion of different virulence factors; adhesion to biotic and abiotic surfaces as well as biofilm formation, or iron metabolism.

This Research Topic (consisting of original research articles, commentaries, opinion papers, and reviews) aims to collect advances in the fields of understanding the physiological, ecological, epidemiological, and molecular aspects of pathogenic and/or opportunistic flavobacteria and/or their corresponding hosts:
 Pathogenic mechanisms for colonization and/or infection development.
 Gliding motility and secretion systems.
 Development of new genetic tools for flavobacteria manipulation and detection.
 Physiology and metabolism of pathogenic flavobacteria.
 Comparative genome analysis for a better understanding of pathogenic mechanisms and their evolution.
 Epidemiological studies.
 Prevention and treatment for flavobacteria.
 Flavobacteriaceae-host interactions.