The study of microbial pathogenesis has been primarily a reductionist science since Koch’s principles. human microbiome. I discuss recent advances in the emerging discipline of sociomicrobiology and how it provides a framework to dissect microbial interactions in single and multispecies communities without compromising mechanistic detail. The study of bacterial pathogenesis can benefit greatly from incorporating concepts from other disciplines such as social evolution theory and microbial ecology where communities their interactions with hosts and with the environment play key roles. INTRODUCTION Microbiology has gathered much attention in recent years thanks to major scientific advancements in the microbiome field. Large-scale projects such as the NIH funded Human Microbiome Project [1-3] provide extensive catalogues of the microbes that live in and on the human body. Statements like “the human body is home bacteria that outnumber human cells by more than 10: 1” or that “the genetic content of these bacteria can be 100x the that of the human genome” are popular in mainstream media and even relatively well known to the general public now. Vast explorations of the human and non-human microbiomes are to large extent boosted by recent breakthroughs in DNA sequencing and community metagenomics [4-6] and the many studies that emerged reveal an expanding role of Anemoside A3 multispecies host-associated microbial communities in many host functions [7 8 Arguably one of the most Anemoside A3 Anemoside A3 notable functions of commensal microbiota i. e. non-pathogenic microbes is in protecting the sponsor against colonization by microbes . This is an exciting area of research that helps explain many puzzles in pathogenesis such as why individuals exposed to the same pathogen can differ in the level of infection. It can also explain why patients can have Anemoside A3 increased risk of infections after antibiotic therapy when antibiotics have the undesired effect of destroying the commensal microbiota that would naturally protect against pathogen invasion. Understanding how microbiomes protect against Rabbit polyclonal to IL9. colonization by pathogens and other related aspects of microbial pathogenesis requires a new set of experimental and theoretical tools. The focus must broaden beyond the single pathogen as the cause of disease and start to consider also the host resident microbiota and its important role in modulating infection. Understanding how microbial communities function how they are assembled and how they change in time after perturbations like antibiotics or diet changes is a complex problem that is best suited to an integrative approach. Fortunately there is an extensive body of knowledge on the functioning of complex biological consortia in the fields of ecology and evolution that we can learn from. Here we start by reviewing the findings of sociomicrobiology a discipline that aims to address how bacteria function in communities . Then we analyze how seemingly cooperative microbes may actually be driven by selfish motives even within communities where every microbe is of the same species. We move on to multispecies communities a more complex scenario where both conflict and cooperation can occur and in fact may both be essential components of the robust behaviors that micro-ecosystems often have. We end with an ecologist’s view of the human microbiome and a discussion of how resistance against pathogen colonization is best interpreted as a problem in ecology. BIOFILMS QUORUM SENSING AND Anemoside A3 THE DAWN OF SOCIOMICROBIOLOGY Bacteria are rather social organisms. Biofilms dense communities of bacteria are a common cause of persistent infections and the list of biofilm forming pathogens includes common threats such as     [15 16 and . Microbiologists came to realize the importance of biofilm formation in pathogenesis in part because bacteria once in biofilms have much higher tolerance to antibiotics and the mechanism of this tolerance appears to be distinct from conventional antibiotic resistance [18 19 Biofilms saw a surge in interest among the microbiology community in the late 1990’s. Even though it was well known that microbes formed dense surface attached films and that these films have medical implications the topic seemed to get more interest from engineers who were interested in the mechanics of biofilm formation and.