The Microbial Cities vision of bacterial biofilms has dominated our understanding of the development and functioning of bacterial aggregations for the past years, during which active sludge, clumps, colonies, flocs, mats, pellicles, rafts, slimes, zooglea, etc. have been largely forgotten or ignored. Although the medically inspired developmental model of human pathogen biofilms has merits including providing a rationale for the development of anti-biofilm therapeutics, it fails to provide links to other types of bacterial aggregation that are commonly found in a wide range of natural and manmade environments. Possibly as a result, applied and environmental microbiologists tend to avoid the term biofilm and use others such as microbial mats instead. Here we challenge the simplistic planktonic independent and free-swimming bacteriabiofilm sessile and co-operative bacteria dichotomy, and consider biofilms within the larger context of bacterial aggregations. By placing biofilms into context, which we see as a continuum of aggregations or communities with varying abiotic and biotic properties, fundamental physical, biological, and evolutionary ecological processes that effect community development and function can no longer be considered unique to biofilms, but may also be important in other aggregations that develop over time and change in nature depending on prevailing conditions. By doing this, we will be better able to distinguish those processes which govern bacterial colonisation and ecological success in a wider sense from those that are unique to particular environments and specialised strategies.Keywords: Bacterial aggregations, Biofilms, Colonies, Communities, Planktonic and sessile bacteria © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
. IntroductionModern biofilm research often acknowledges the seminal reviews of Costerton et al. [ , ] in which a conceptual model of biofilm development and structure was first presented. In this model, biofilm development is described as a series of linked events, from the attachment of free-swimming planktonic bacteria to a submerged solid surface, the growth of microcolonies in simple conical structures, and subsequent maturation as larger mushroom-shaped structures which have been envisioned as Microbial Cities this appellation may derive from reviews entitled City of Microbes and Microbial Metropolis [ , ], but we are unsure . Equally important to this description was the dichotomous differentiation between independent freeswimming planktonic bacteria with the co-operative and co-ordinated communities of sessile bacteria forming biofilms, and the somewhat teleological suggestion that surface-attached communities allowed growth in harsh conditions which planktonic bacteria could not survive [ ]. This view of comple...