Modelling bacterial growth

Some bacteria live closely together, giving rise to colonies of complex geometrical patterns. To do so, bacteria sense and respond to their local environment by secreting pheromones or other chemoattractant molecules. Our knowledge on colony dynamics and what affects bacterial behaviour at the macroscopic level is limited.

Using a mathematical modelling approach, scientists on the EU-funded project 'Multiscale modeling and simulation of bacterial colonies' (BACTERIAL COLONY SIM) tried to simulate and explain bacterial behaviour in colonies. The work focused on a particular type of bacteria from the Bacillus family called Paenibacillus. The key objective was to understand how bacteria cooperate and regulate the growth dynamics of millions of other members of the strain.

The study of bacterial growth was categorised into three stages, namely the single-cell stage, the intermediate swarm stage and the macroscopic colony stage. Swarms contain a few thousand cells and are considered to be the basic organisational unit of bacterial growth.

To understand bacterial collective behaviour, the consortium developed algorithms to analyse swarm behaviour. They found a highly synchronised movement in response to nutrients, waste products, environmental sensing and intercellular signalling. The response to external conditions plays a role in swarm dynamics, enabling bacteria to move rapidly over surfaces. Special emphasis was also given to bacterial swarm function under high antibiotic concentrations.

Taken together, BACTERIAL COLONY SIM's modelling approach helped characterise the patterns and determinants of bacterial growth. The generated information could form the basis for future antibacterial strategies that aim to abolish swarm formation.