Viewing biofilms within the larger context of bacterial aggregations

The ‘Microbial Cities’ vision of bacterial biofilms has dominated our understanding of the development and functioning of bacterial aggregations for the past 20 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 man-made 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 bacteria)-biofilm (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.

Global citizenship education: a sociological critique

This paper considers the recent focus on citizenship within education by taking curricular reform within Scottish secondary schooling as a case study. In Scotland the Curriculum for Excellence reform places citizenship as one of four main capacities that pupils must work towards as part of their education. A central theme in this reform is the need for students to take a global perspective and work across different disciplines. In this model of citizenship education learners are enabled to develop their sense of citizenship identity in response to a fast-paced world of innovation and change. Citizenship is therefore linked to a futurist agenda, where the learner-citizen is positioned as an ongoing project, as something to be worked at or perhaps worked on. However, this kind of notion of agency is an expression of an ideological construction of the citizen as a flexible resource for society. Such citizens are active in the sense of being adaptive to change through utilizing intellectual skills but without a sense of identity grounded in one's commitments or reflexive engagement with different forms of understanding. The paper offers a critical assessment of this learner-citizen discourse as focusing on ratiocination rather than relational identity.