We conducted a physiological analysis of biofilm formation
by H. volcanii DS2 due to several advantages of
using this species as a model for archaeal biofilm formation.
The wild-type H. volcanii DS2 strain was cultivated
from sediment from the Dead Sea in 1975 [39]: it is a
relatively fast-growing non-fastidious mesophile, requiring
no special equipment to grow in the laboratory [40,41] and
was the first archaeon to be artificially transformed [42].
H. volcanii DS2 has an available genome sequence [43] and
an expanding genetic and proteomic toolbox [42,44–49].
Haloarchaea also undergo promiscuous gene transfer in the
environment [50–52] and are excellent species for studying
evolutionary processes due to island-like distribution
[53–55]. We hypothesize that a cell-to-cell contactdependent
gene transfer mechanism in H. volcanii
[56–58] may be active when cells are contained within
biofilm communities. The available genetic system allowed
us to engineer a H. volcanii strain expressing GFP for
three-dimensional biofilm imaging by confocal laser scanning
microscopy (CLSM). Here we characterize key aspects
of H. volcanii biofilm structural development, composition,
dynamics and recombination frequency.