Shaping the growth behaviour of biofilms initiated from bacterial aggregates

Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities

Local government reform: compromise through cross-cutting cleavages

Public sector reforms often take place in heterogeneous reform environments. Key political, administrative, and societal actors often advocate different definitions of problems and solutions. A major leadership challenge is to choose a reform strategy that ensures the requisite level of support, even when the initial conflict structure is highly complex. Using cleavage theory, we develop assumptions about how the reform leader’s assessment of the initial conflict affects the leader’s choice between three distinct reform strategies. These assumptions are applied to a case study of a complex and contested public sector reform, Norway’s national local government reform. We show how the government’s choice of a reform strategy can be understood in light of cleavage theory, and discuss the implications of these findings for further theory development