title: Membrane fatty acids adaptive profile in the simultaneous presence of arsenic and toluene in Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5 strains.
abstract: Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5, two arsenic-resistant bacterial strains previously isolated from sediments of the Orbetello Lagoon, Italy, were tested for their adaptation to mixed contaminants on the level of membrane fatty acid composition. The two bacterial strains were characterized by high levels of arsenic resistance, and Pseudomonas sp. ORAs5 was also shown to be solvent-tolerant. The bacterial strains were exposed to mixtures of two toxic compounds: arsenic at fixed concentrations and toluene in variable amounts or, alternatively, toluene at constant values along with arsenic added at variable concentrations. Both strains react to the contaminants by changing the composition of their membrane fatty acids. Bacillus sp. strain ORAs2 showed a correlation between growth rate decreases and fatty acids degree of saturation increases in both cases, although pointedly in the presence of 1, 2, and 3 mM of toluene and different additions of arsenic, counteracting membranes fluidity induced by toxic compounds. In Pseudomonas sp. ORAs5, adaptive changes in membrane composition was observed both in terms of increases in the degree of saturation and in the trans/cis ratio of unsaturated fatty acids in the presence of varying toluene and constant arsenic concentrations, whereas only minor changes occurred with increasing arsenic and constant toluene concentrations. Thus, on the level of membrane composition, Bacillus sp. ORAs2 showed a higher potential for adaptation to the presence of mixed pollutants, suggesting its probable suitability for bioremediation purposes.
authors.affiliation: Department of Environmental Sciences, University of Siena, Via P.A. Mattioli, 4, 53100 Siena, Italy.
authors.forename: Milva
authors.initials: M
authors.lastname: Pepi
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Heipieper
authors.forename: Janett
authors.initials: J
authors.lastname: Fischer
authors.forename: Marcella
authors.initials: M
authors.lastname: Ruta
authors.forename: Margherita
authors.initials: M
authors.lastname: Volterrani
authors.forename: Silvano E
authors.initials: SE
authors.lastname: Focardi
mesh_terms: D000222:Adaptation, Physiological; D001151:Arsenic / Q000378:metabolism / Q000633:toxicity*; D001407:Bacillus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D001673:Biodegradation, Environmental; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000378:metabolism*; D007558:Italy; D008560:Membrane Fluidity / Q000187:drug effects; D008563:Membrane Lipids / Q000378:metabolism*; D011549:Pseudomonas / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D014050:Toluene / Q000378:metabolism / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D014874:Water Pollutants, Chemical; D014050:Toluene; D001151:Arsenic