Comparative Genomic Analysis of Halophilic and Xerophilic Microbes to
Elucidate Adaptions to Chaotropic and Low Water Activity Environments
Abstract
Studies on the molecular mechanisms of microbial adaptation in
chaotropic and low water activity (aw) environments are poorly
understood. Chaotropic environments are characterized as salt rich,
MgCl2 and CaCl2, which lowers the availability of water for biological
processes. PATRIC, an integrated genomic browsing tool containing vast
libraries of sequenced genomes, can help us identify unique genetic
markers in chaophilic and xerophilic microbes. Halophilic microbes are
characterized as obligate hypersaline with the ability to tolerate
exposure to chaotropic agents. Microbes with the greatest tolerance in
these extreme environments must have advanced adaptive methods.
Halobacterium salinarum and Haloquadratum walsbyi are chaotolerant and
well adapted to low water activity. Haloquadratum walsbyi is unique
among the halophilics as having the highest tolerance for chaotropes and
its square shape. Performing comparative genomics using fully sequenced
halophilic archaea such as Halobacterium salinarum NRC-1, a model
halophile, and Haloquadratum walsbyi C23, we were able to identify genes
that confer adaptation to chaotropic and low aw environments, as well as
individual adaptations that may be responsible for the varying levels of
tolerance in chaotropic environments . Characterizing genes associated
with chaotolerance and low aw adaptations can help elucidate the
cellular functions that make these microbes unique. Chaotropic brines
may be used as analogs to study the origin of life and the possibility
of suitable environments hosting extremophilic microbes on other planets
like the Martian brines and the icy moons of Europa; therefore, studying
the microbiome of chaotropic environments are essential in the field of
astrobiology.