Biology Reference
In-Depth Information
CHAPTER TWO
Genomics of Salt Acclimation:
Synthesis of Compatible Solutes
among Cyanobacteria
Martin Hagemann
*
University Rostock, Institute Biological Sciences, Plant Physiology, Rostock, Germany
*Corresponding author: E-mail: martin.hagemann@uni-rostock.de
Contents
1. Introduction
28
2. BasicSaltAcclimationStrategy
29
3. CompatibleSolutes
30
3.1. Sucrose
31
3.2. Trehalose
40
3.3. Glucosylglycerol
42
3.4. Glucosylglycerate
44
3.5. GlycineBetaine
45
4. Regulation
47
5. CyanobacterialBiotechnologyandSaltAcclimation
50
Abstract
Duringtheirlongevolution,cyanobacteriawereabletoinhabitalllight-exposedeco-
systems.Oneofthemainenvironmentalfactorsdeterminingcyanobacterialdistribu-
tion is the salinity of the surroundingmedium. Among cyanobacterial strains, three
main salt-tolerance groups can be distinguished: low- and moderate-halotolerant
cyanobacteria aswell ashypersaline strains.Regardlessof the final salt resistance, all
cyanobacteriaapplytwobasicstrategiesforasuccessfulacclimationtoenhancedsalt
concentrations: accumulationof compatible solutes combinedwith active exportof
toxic ions,particularlyNa
+
andCl
−
.During the years1991-2010, themolecularbasis
ofthesemechanismshasbeenelucidated.Today,manycompletegenomesequences
appear indatabasesofcyanobacterial strains,whichareoftendifficult tocultivate in
the laboratory.These datawere used here to screen the genomes ofmore than 60
cyanobacteria regardingtheircompatiblesoluteaccumulationcapacities.Hence,the
existingknowledgeaboutcyanobacterialsaltacclimationwasusedtoannotatebasic
salt-resistancemechanisms on the basis of genome information.Understanding the
basicsaltacclimationamongcyanobacteriawillalsobeusefulfortheirfuturebiotech-
nologicalapplication,whichwillbeperformedpreferentiallyinsalinewaters.
