Transcriptome and membrane fatty acid analyses reveal different strategies for responding to permeating and non-permeating solutes in the bacterium Sphingomonas wittichii

BMC Microbiology

Research Article

Hermann J Heipieper¹  Edith Coronado²  Silvia K Moreno-Forero²  Jan Roelof van der Meer²  David R Johnson³ 

[1] Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, 04318, Leipzig, Germany;Department of Fundamental Microbiology, University of Lausanne, 1015, Lausanne, Switzerland;Department of Fundamental Microbiology, University of Lausanne, 1015, Lausanne, Switzerland;Department of Environmental Sciences, Swiss Federal Institute of Technology Zürich (ETHZ), 8092, Zürich, Switzerland;Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600, Dübendorf, Switzerland;

关键词: Water Potential;    Specific Growth Rate;    Sodium Chloride;    PEG8000;    Transcriptome Profile;   

DOI  :  10.1186/1471-2180-11-250

 received in 2011-09-01, accepted in 2011-11-14,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundSphingomonas wittichii strain RW1 can completely oxidize dibenzo-p-dioxins and dibenzofurans, which are persistent contaminants of soils and sediments. For successful application in soil bioremediation systems, strain RW1 must cope with fluctuations in water availability, or water potential. Thus far, however, little is known about the adaptive strategies used by Sphingomonas bacteria to respond to changes in water potential. To improve our understanding, strain RW1 was perturbed with either the cell-permeating solute sodium chloride or the non-permeating solute polyethylene glycol with a molecular weight of 8000 (PEG8000). These solutes are assumed to simulate the solute and matric components of the total water potential, respectively. The responses to these perturbations were then assessed and compared using a combination of growth assays, transcriptome profiling, and membrane fatty acid analyses.ResultsUnder conditions producing a similar decrease in water potential but without effect on growth rate, there was only a limited shared response to perturbation with sodium chloride or PEG8000. This shared response included the increased expression of genes involved with trehalose and exopolysaccharide biosynthesis and the reduced expression of genes involved with flagella biosynthesis. Mostly, the responses to perturbation with sodium chloride or PEG8000 were very different. Only sodium chloride triggered the increased expression of two ECF-type RNA polymerase sigma factors and the differential expression of many genes involved with outer membrane and amino acid metabolism. In contrast, only PEG8000 triggered the increased expression of a heat shock-type RNA polymerase sigma factor along with many genes involved with protein turnover and repair. Membrane fatty acid analyses further corroborated these differences. The degree of saturation of membrane fatty acids increased after perturbation with sodium chloride but had the opposite effect and decreased after perturbation with PEG8000.ConclusionsA combination of growth assays, transcriptome profiling, and membrane fatty acid analyses revealed that permeating and non-permeating solutes trigger different adaptive responses in strain RW1, suggesting these solutes affect cells in fundamentally different ways. Future work is now needed that connects these responses with the responses observed in more realistic scenarios of soil desiccation.

【 授权许可】

CC BY   
© Johnson et al; licensee BioMed Central Ltd. 2011