Abstract
Twenty-three microorganisms taken from the Inland Sea in Western Japan formed colonies on plates containing 2M NaCl, of which 15 isolates showed growth rates of more than 0.5 (doublings/h) at 30°C in the presence of 2M NaCl. The isolates thus selected were classified into two groups by their growth patterns in response to NaCl concentrations added externally. Four isolates (group I) did not grow in the presence of 20mM and 3M NaCl, but they showed a peak growth of 1.67-2.14 doublings/h at 0.5M. Three isolates (group IIA) grew in the presence of 20mM (0.92-0.95 doublings/h) and 3M (0.29-0.33 doublings/h) NaCl, indicating that they are halotolerant microorganisms. Another 8 microorganisms (group IIB) also showed the halotolerant growth pattern. These findings indicate that halotolerant microorganisms are widely distributed in seawater.
