In this Analysis article, Flemming and Wuertz calculate the total number of bacteria and archaea on Earth and estimate the fraction that lives in biofilms. They propose that biofilms are the most prominent and influential type of microbial life.
In most natural, clinical and industrial settings, microorganisms exist in biofilms that associate with biotic and abiotic surfaces. These three-dimensional single-species or polymicrobial communities are embedded in a self-produced matrix that enables the intercellular exchange of metabolites, genetic material and signalling molecules. In addition, these microbial consortia provide protection against predators and antimicrobial agents, and they are widely studied owing to their clinical relevance, their ubiquitous nature and the functional insights that they provide into microbial ecology. Although most natural biofilms are polymicrobial, much has been learned about the basic biology of these communities through the study of single-species biofilms using model bacteria; however, the field is currently experiencing a paradigm shift and is moving towards the study of multi-species communities in an effort to learn more about competitive and cooperative microbial behaviour.
In this series of articles, Nature Reviews Microbiology explores the fascinating insights into biofilm ecology, the molecular mechanisms and regulation of biofilm formation, and the emerging physiological properties of this universal microbial lifestyle.
Most infections with enterococci involve the formation of biofilms, which further increases the antibiotic tolerance and resistance of these priority pathogens. In this Review, Kline and colleagues summarize how enterococci form biofilms, including polymicrobial biofilms, and highlight new treatment options.
Archaea have been found in biofilms in a variety of habitats. In this Review, Albers and colleagues explore the different stages of archaeal biofilm development and highlight the similarities and differences between archaea and bacteria. They also consider their role in different industrial processes.
In this Review, Brun and colleagues summarize our understanding of the mechanisms governing bacterial adhesion at the single-cell level, including the physical forces experienced by a cell before reaching the surface, the first contact with a surface and the transition from reversible to permanent adhesion.
Implant infections are often resistant to treatment and immune responses owing to the formation of biofilms. In this Review, Arciola, Campoccia and Montanaro summarize the strategies that pathogens such as staphylococci use to infect implants and novel treatment approaches.
The ability ofCandida albicans to form biofilms is a major cause of disseminated bloodstream infections. Here, Nobile and colleagues review our current understanding of the processes involved in the formation of C. albicans biofilms, the core transcriptional network that regulates biofilm development, and polymicrobial biofilms that are formed by C. albicansand certain bacterial species.
In this Review, Stoodley and colleagues discuss current therapeutic strategies and those under development for the treatment of pathogenic biofilms. They explore novel technologies that promise to enhance the efficacy of current therapeutics or provide novel effects and argue that treating biofilm infections requires combination therapies.
Numerous metabolic functions, social interactions and survival mechanisms are specific to, or more pronounced in, biofilms than in planktonic cells. In this Review, Flemming and colleagues highlight the central role of the self-produced matrix in establishing these 'emergent properties' of biofilms.
Microbial biofilms exhibit vast complexity in terms of both resident species composition and phenotypic diversity. Here, Foster and colleagues discuss theoretical and experimental work that reveals how the spatial arrangement of genotypes within microbial communities influences the cooperative and competitive cell–cell interactions that define biofilm form and function.
Biofilms dominate microbial life in streams and rivers. In this Review, Battin and colleagues describe the interactions between the microbiome of stream biofilms and ecosystem processes, and they consider the effects of global ecosystem change and climate change on these biofilms.
The spatial organization of microbial communities can affect their function, both in the environment and during infections. In this article, Whiteley and colleagues review the factors that govern biogeography during polymicrobial infections and how spatial positioning can influence bacterial virulence. They also discuss how targeting biogeography can be used as a therapeutic strategy.
Bacteria form biofilms as a strategy for survival and persistence. In this Review, Yildiz and colleagues discussVibrio cholerae surface attachment and the biofilm matrix components. They also review the regulatory network that governs V. choleraebiofilm formation, including the transcriptional regulators of key genes involved in this process, as well as the roles of small nucleotides and small RNAs.