Question

You are a bacterium living well in a community of other bacteria, phage and yeasts. Resources are partitioned well; cooperation is efficient and abundant. But what is this? One hundred outside bacteria are trying to enter and become established and this is not a welcomed event.

How would you use your secretion system to defend your community and yourself? How would you also use your secretion system to support the existence and well-being of other microorganisms in your biofilm community?

Answer 1

Biofilms are communities of microorganisms that are attached to a surface. The structure of the extracellular polymeric substance (EPS) matrix of biofilms is composed of one or more of extracellular polysaccharides, DNA and proteins. Channels in the biofilm allow for water, air and nutrients to get to all parts of the structure. Because of this structure, nothing else including bacteria outside the biofilm cannot enter the biofilm. Bacteria within biofilm communities ‘talk’ to each other and take specialized functions. As the biofilm matures, more biofilm scaffolds, such as proteins, DNA, polysaccharides, etc. are secreted into the biofilm by the entrapped bacteria.In order to form a biofilm, bacteria have to synchronize their gene expression and some use quorum-sensing (QS) systems to achieve this. QS is a mechanism by which bacteria apparently monitor cell density and regulate collective behaviors. It is worth pointing out that the issue of bacterial population monitoring via QS is still hotly debated and many alternative hypotheses have been proposed for the role of molecules that are involved in QS. In biofilm, major role is played by quorum sensing machanism for the support of biofilm. In addition to that, bacterial system consist of various secretion system.