46 cm reversed-phase column The mobile phase consisted of 70% v/

46 cm reversed-phase column. The mobile phase consisted of 70% v/v acetonitrile at a flow rate of 1 mL min−1. Compatible solute quantification was related to the protein concentration determined using Lowry’s method (Lowry et al., 1951). The concentrations of the zwitterionic osmolytes were calculated using the appropriate standard solutions click here of each compound (1 mg mL−1). Chlorobaculum parvum UdG6501Lms was used for the isolation and further structural characterization (using both NMR and MS analyses) of NeABL because it was the fastest-growing GSB strain assayed (ranging from 0.026 to 0.006 h−1 at 3% NaCl). A minimum of 5 g of lyophilized

bacterial cell mass was extracted by applying the extraction method cited above. The resulting aqueous supernatant phase was concentrated by evaporating the solvent at reduced pressure and subsequently desalted on a column of AG11A8 (Bio-Rad) (2 × 72 cm). The separation of such compound from a mix of compatible solutes, particularly including β-glutamate, was just achieved by a cation exchanger column (Dowex 50 W × 8/100–200 mesh) in Na+ form and elution with

a pH gradient (1 M NaHCO3– 1 M Na2CO3). Residual carbonate was subsequently removed by chromatography on an ion retardation column (AG11A8). In those cases in which aqueous cell extracts just contained a mix of α-glutamate (anionic) and the zwitterionic NeABL, a unique ion retardation for step was necessary to purify the specified compound, as it was shown with cell extracts of B. cereus CECT 148T (eq. ATCC 14579, DSM 31). Several GSB type strains AT9283 molecular weight (P. vibrioformis DSM 260T, C. thiosulfatophilum DSM 249T, C. phaeovibrioides DSM 269T, C. luteolum DSM 273T) and isolated strains from both hypersaline inland water bodies and salty coastal lagoons

have been analyzed using 13C-NMR for the detection of compatible solutes. Experimental results enabled to disclose the spectrum of compatible solutes in members of all major phylogenetic groups of GSB (Fig. 1; Table 1) and suggested a common strategy among halophilic and halotolerant strains, despite their different phylogenetic affiliation. Besides accumulating trehalose, which was the only solute described in GSB to date (Welsh & Herbert, 1993), they were found to be able to accumulate several compounds not found previously in this group: NeABL, which has been determined by structural characterization, and the anionic osmolytes β-glutamate and l-α-glutamate (as confirmed with commercial standards). These compounds in GSB can be unequivocally assigned to osmotic responses of these strains because the halotolerant GSB strain C. parvum UdG6501Lms did not accumulate any compatible solute at significant levels in freshwater-like media (data not shown).

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