Biofilm formation is a survival strategy for many microorganisms. Within biofilms, microorganisms live in multicellular communities enclosed in a protective matrix that enables them to survive harsh conditions and resist conventional treatments. The ability of biofilm-forming microorganisms to inhabit different biotic and abiotic surfaces facilitates their widespread existence in different environments including health care facilities, water systems, ships, and even living hosts. Hence, this microbial phenotype became a major concern in various sectors including public health, medicine, and industry. The challenge imparted by the detrimental effects of biofilms has sparked the interest of many researchers in tackling this problem. Biofilms are not simply a collection of microorganisms but can be considered as new materials. Current research efforts have focused on understanding the mechanisms of biofilm formation and factors affecting their structures, as well as innovative approaches for combating biofilms and achieving rapid biofilm detection. Prevention and proper management of biofilms necessitates a deep understanding of the mechanisms of their formation and the factors affecting their development. It is established that biofilm formation undergoes multiple stages from initial surface adhesion to maturation and dispersion. However, how bacteria trigger, regulate and modulate each stage is not yet well understood. Additionally, early detection of biofilms facilitates early intervention and, consequently, reduction in the economic loss and clinical burden. However, detection of cells within biofilms is particularly challenging and innovative sensing, tracking and diagnostic technologies are needed. Clinically, biofilm formation is a key aspect of antibiotic resistance. Biofilms are not merely protective barriers against antibiotics and the host immune system, but also harbour non-growing “persister” bacteria that survive antibiotics by virtue of their dormancy. It is established that both persisters and biofilms are implicated in chronic infections. However, the triggering factors of their formation are not fully understood. Viable but non culturable (VBNC) cells is another group of non-growing bacteria that can inhabit biofilms and remain dormant for extended periods. The trigger for their formation and revival as well as clinical relevance is unclear.

Materials and equipment in food processing industries are colonized by surface-associated microbial communities called biofilms. In these biostructures microorganisms are embedded in a complex organic matrix composed essentially of polysaccharides, nucleic acids and proteins. This organic shield contributes to the mechanical biofilm cohesion and triggers tolerance to environmental stresses such as dehydratation or nutrient deprivation. Notably, cells within a biofilm are more tolerant to sanitation processes and the action of antimicrobial agents than their free living (or planktonic) counterparts. Such properties make conventional cleaning and disinfection protocols normally not effective in eradicating these biocontaminants. Biofilms are thus a continuous source of persistent microorganisms, including spoilage and pathogenic microorganisms, leading to repeated contamination of processed food with important economic and safety impact. Alternatively, in some particular settings, biofilm formation by resident or technological microorganisms can be desirable, due to possible enhancement of food fermentations or as a means of bioprotection against the settlement of pathogenic microorganisms. In the last decades substantial research efforts have been devoted to unravelling mechanisms of biofilm formation, deciphering biofilm architecture and understanding microbial interactions within those ecosystems. However, biofilms present a high level of complexity and many aspects remain yet to be fully understood. A lot of attention has been also paid to the development of novel strategies for preventing or controlling biofilm formation in industrial settings. Further research needs to be focused on the identification of new biocides effective against biofilm-associated microorganisms, the development of control strategies based on the inhibition of cell-to-cell communication, and the potential use of bacteriocins, bacteriocin-producing bacteria, phage, and natural antimicrobials as anti-biofilm agents, among others. This Research Topic aims to provide an avenue for dissemination of recent advances within the “biofilms” field, from novel knowledge on mechanisms of biofilm formation and biofilm architecture to novel strategies for biofilm control in food industrial settings.

Materials and equipment in food processing industries are colonized by surface-associated microbial communities called biofilms. In these biostructures microorganisms are embedded in a complex organic matrix composed essentially of polysaccharides, nucleic acids and proteins. This organic shield contributes to the mechanical biofilm cohesion and triggers tolerance to environmental stresses such as dehydratation or nutrient deprivation. Notably, cells within a biofilm are more tolerant to sanitation processes and the action of antimicrobial agents than their free living (or planktonic) counterparts. Such properties make conventional cleaning and disinfection protocols normally not effective in eradicating these biocontaminants. Biofilms are thus a continuous source of persistent microorganisms, including spoilage and pathogenic microorganisms, leading to repeated contamination of processed food with important economic and safety impact. Alternatively, in some particular settings, biofilm formation by resident or technological microorganisms can be desirable, due to possible enhancement of food fermentations or as a means of bioprotection against the settlement of pathogenic microorganisms. In the last decades substantial research efforts have been devoted to unravelling mechanisms of biofilm formation, deciphering biofilm architecture and understanding microbial interactions within those ecosystems. However, biofilms present a high level of complexity and many aspects remain yet to be fully understood. A lot of attention has been also paid to the development of novel strategies for preventing or controlling biofilm formation in industrial settings. Further research needs to be focused on the identification of new biocides effective against biofilm-associated microorganisms, the development of control strategies based on the inhibition of cell-to-cell communication, and the potential use of bacteriocins, bacteriocin-producing bacteria, phage, and natural antimicrobials as anti-biofilm agents, among others. This Research Topic aims to provide an avenue for dissemination of recent advances within the "biofilms" field, from novel knowledge on mechanisms of biofilm formation and biofilm architecture to novel strategies for biofilm control in food industrial settings.

The transmission route used by many bacterial pathogens of clinical importance includes a step outside the host; thereafter refer to as the non-clinical environment (NCE). Obvious examples include foodborne and waterborne pathogens and also pathogens that are transmitted by hands or aerosols. In the NCE, pathogens have to cope with the presence of toxic compounds, sub-optimal temperature, starvation, presence of competitors and predators. Adaptation of bacterial pathogens to such stresses affects their interaction with the host. This Research Topic presents important concept to understand the life of bacterial pathogens in the NCE and provides the reader with an overview of the strategies used by bacterial pathogens to survive and replicate outside the host.