title: Protective role of glycerol against benzene stress: insights from the Pseudomonas putida proteome.
abstract: Chemical activities of hydrophobic substances can determine the windows of environmental conditions over which microbial systems function and the metabolic inhibition of microorganisms by benzene and other hydrophobes can, paradoxically, be reduced by compounds that protect against cellular water stress (Bhaganna et al. in Microb Biotechnol 3:701-716, 2010; Cray et al. in Curr Opin Biotechnol 33:228-259, 2015a). We hypothesized that this protective effect operates at the macromolecule structure-function level and is facilitated, in part at least, by genome-mediated adaptations. Based on proteome profiling of the soil bacterium Pseudomonas putida, we present evidence that (1) benzene induces a chaotrope-stress response, whereas (2) cells cultured in media supplemented with benzene plus glycerol were protected against chaotrope stress. Chaotrope-stress response proteins, such as those involved in lipid and compatible-solute metabolism and removal of reactive oxygen species, were increased by up to 15-fold in benzene-stressed cells relative to those of control cultures (no benzene added). By contrast, cells grown in the presence of benzene + glycerol, even though the latter grew more slowly, exhibited only a weak chaotrope-stress response. These findings provide evidence to support the hypothesis that hydrophobic substances induce a chaotropicity-mediated water stress, that cells respond via genome-mediated adaptations, and that glycerol protects the cell's macromolecular systems. We discuss the possibility of using compatible solutes to mitigate hydrocarbon-induced stresses in lignocellulosic biofuel fermentations and for industrial and environmental applications.
authors.affiliation: MBC, School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK.
authors.forename: Prashanth
authors.initials: P
authors.lastname: Bhaganna
authors.affiliation: Environmental Microbiology Laboratory, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany.|Molecular Biology Department, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany.
authors.forename: Agata
authors.initials: A
authors.lastname: Bielecka
authors.affiliation: Environmental Microbiology Laboratory, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany.|Central Facility for Microscopy, Helmholtz Centre for Infection Research, D-38124, Braunschweig, Germany.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Molinari
authors.affiliation: MBC, School of Biological Sciences, Institute for Global Food Security, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK. j.hallsworth@qub.ac.uk.
authors.forename: John E
authors.initials: JE
authors.lastname: Hallsworth
mesh_terms: D001554:Benzene / Q000494:pharmacology*; D005990:Glycerol / Q000494:pharmacology*; D009997:Osmotic Pressure / Q000187:drug effects; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D016958:Pseudomonas putida / Q000187:drug effects* / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D020543:Proteome; D001554:Benzene; D005990:Glycerol
keywords: Benzene toxicity; Bioremediation; Chaotrope-stress response; Compatible solutes; Glycerol; Hydrocarbon-and oil degradation; Osmotic adjustment