Other studies with P. putida showed that permeating and non-permeating solutes had different effects on the relative amounts of cis and trans membrane fatty acid isomers [13, 18] as well as on the accumulation
of the compatible solutes K+ and betaine . Thus, the responses to permeating and non-permeating solutes appear to be different in P. putida. Why these responses are different and how these responses are independently regulated, however, is not well understood. The primary objective of this study was to evaluate how Sphingomonas wittichii strain RW1 responds to the permeating selleck chemicals llc solute sodium chloride or the non-permeating solute PEG8000, which are assumed to simulate the solute and matric components of the total water potential, and then compare these responses to identify
commonalities and differences between them. The responses https://www.selleckchem.com/products/gdc-0068.html of cells were primarily investigated by transcriptome profiling and were further combined with growth rate and membrane fatty acid analyses. The temporal adaptation to these perturbations was also investigated by comparing the short-term and long-term transcriptional AG-881 mouse responses to sodium chloride and PEG8000. Although other studies have used transcriptome profiling to investigate the responses to changes in water potential [20–25], this study is unique by directly comparing the responses to permeating and non-permeating solutes, Sclareol which can help reveal whether these solutes affect cells in fundamentally different ways. Moreover, these responses have not been extensively explored in the Sphingomonas genus, and this research therefore fills an important gap in our understanding of this bioremediation-relevant group of bacteria. Methods Growth and culture conditions Sphingomonas
wittichii strain RW1 was grown in 100-mL culture flasks containing 20 mL of a phosphate-buffered mineral medium (medium DSM457 from the German Resource Centre for Biological Material, Braunschweig, Germany) and 5 mM of sodium salicylate as the sole carbon source (for simplicity hereafter called DSM457-Sal medium). All cultures were incubated at 30°C with shaking at 180 rpm. The water potential of standard DSM457-Sal medium at 30°C was estimated using the van’t Hoff equation [8, 11] and is approximately -0.235 MPa. Effect of sodium chloride and PEG8000 on the specific growth rate To investigate the effect of the water potential on the specific growth rate of strain RW1, DSM457-Sal medium was amended with sodium chloride or PEG8000 to reduce the water potential of standard DSM457-Sal medium by 0.25, 0.5, 1.0, 1.5, or 2.5 MPa. The required concentrations of sodium chloride were calculated using the van’t Hoff equation [8, 11] and were 2.9, 5.8, 11.6, 17.4, or 29 g per L, respectively.