B. japonicum El09 was obtained from the INTA Culture Collection. Shock stress experiments were carried out in HPM medium (g/L): K2HP04 0.18; MgS04.7H20 0.18; NaCl 0.12; (NH4)2S04 0.39; glycerol 2.4; yeast extract 1.2. Exponential-phase cultures (3-4 xlO6 cells/mL) or stationary-phase cultures (1.5 109cell/mL) were shocked by increasing the NaCl concentration up to 0.1 M or 0.4 M by addition of sterile 4 M NaCl. Soil microcosms were prepared in flat-bottomed glass vials (28 mm diameter x 62 mm length) containing 4 g of dried soil (electrical conductivity (EC) = 1.0 mmhos/cm). The vials with soil were sterilized by autoclaving and sterile distilled water was added to 30% or 65% of field capacity. The soil salinity was increased up to EC = 35 mmhos/cm by addition of sterile 4 M NaCl. Microcosms were inoculated with exponential- or stationary-phase bacteria and incubated at 30°C. CFU counts in samples withdrawn from cultures and microcosms were done in Yeast Mannitol Agar (YMA), with mannitol 1 g/L, incubated for 6 days at 30°C.
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