I’m currently off on my seriously-delayed honeymoon, so over the
next two weeks I’ll be sticking up some posts I enjoyed from my
old blog. They’ve been modified and re-edited to include new
information (and images!) where appropriate, but unfortunately I
won’t be able to answer comments or participate in any
discussion about them until I get back. Although bacteria live
as isolated cells they are constantly communicating with
surrounding bacteria, particularly those of the same species,
and can often band together to form large groups of bacteria
surrounded by a sticky mesh. These are known as biofilms (which
I cover in more detail here). One of the main ways that bacteria
communicate with each other in order to organise structures like
this is by quorum sensing. Quorum sensing uses small molecules
that bacteria can both excrete and sense. When enough bacteria
are in one place then the surrounding concentration of these
small molecules reaches a critical level and can activate the
genes for a variety of diffe