Table 2 Sensitivity of R. leguminosaru m bv. trifolii ros R mutants to detergents, ethanol, and osmotic stress. Strain Minimal inhibitory concentration Hyperosmotic Hypo-osmotic   SDS (% w/v) DOC (% w/v) Ethanol (%v/v) stress (%)* stress (%)* Rt24.2 0.05 ± 0.005 0.10 ± 0.005 4.5 ± 0.28 77.1 51.6 Rt2440 0.02 ± 0.003† 0.030 ± 0.003† 2.3 ± 0.25† 11.5† 13.0† Rt2441 0.02 ± 0.002† 0.030 ± 0.003† 3.0 ± 0.28 11.9† 15.2† Rt2472 0.015 ± 0.002† 0.025

± 0.002† 2.6 ± 0.28† 10.4† 13.3† * – Strains were grown in TY supplemented with 85 mM NaCl (hyperosmotic) or GYM find more medium (hypo-osmotic) supplemented with Dilworth’s vitamins for 2 days, and the growth was compared with that of Selleck AZD5363 strains grown in TY medium. OD600 values were measured. Percentage growth values are the mean and SD from three independent trials. † Difference between the wild type and the rosR mutants is statistically significant at P < 0.05 (Student's t test). The rosR mutants were also significantly more sensitive to hyper- and hypo-osmotic stress than the wild type (Table 2). The mutants achieved only 10-12% of the growth in TY medium supplemented with 85 mM NaCl (the highest NaCl selleck chemicals llc concentration tolerable by the wild type) when compared to a control medium without NaCl. The growth of the rosR mutants was also significantly diminished

in relation to the wild type strain in hypo-osmotic GYM medium. The higher sensitivity of the rosR mutants to hypo-osmotic stress might be explained by an increased permeability of their cell membranes allowing greater amounts of neutral polysaccharide (e.g. β-glucan) to be excreted [34, 35]. Taken together, rosR mutation seems MTMR9 to affect membrane integrity, resulting in an altered sensitivity to detergents,

ethanol, and osmotic stresses. Changes in membrane and extracellular protein profiles of the rosR mutant in relation to the wild type To examine the role of rosR in the putative membrane leakage, membrane and extracellular proteins of Rt2472 and Rt24.2 grown in TY medium were compared by SDS-PAGE (Figure 4B). Some differences in membrane protein profiles were observed, such as two abundant bands with an estimated mass of ~30 kDa and one band of ~63 kDa in Rt2472. In contrast, the amounts of proteins of ~20, 34, and 36 kDa were significantly diminished in this mutant. Based on the literature data, the masses of these three proteins corresponded to mature proteins RopB1 (20.1 kDa), RopA (36 kDA), and RopA1 (38 kDA), which had been identified in R. leguminosarum [36–38]. An extracellular protein profile of R. leguminosarum bv. trifolii 24.2 was very similar to that of R. leguminosarum bv. viciae 3841 [22]. In extracelullar protein profiles of Rt24.