Both organisms formed Gram-positive, non-motile
rod-shape cells. The colonies on PY-BHI solid medium
were rough, round convex and pale cream-colored.
Under anaerobic conditions no growth was observed in
the presence or absence of Cr(VI). Strain RF6T was able
to grow at temperatures between 4 and 30 1C with
optimum temperature at 25 1C and did not grow at
37 1C but RB10T was able to grow at temperatures
between 4 and 37 1C with optimum temperature at 30 1C
but did not grow at 40 1C (Table 1). The optimum pH
for growth of strain RF6T was between 7.0 and 9.0, and
between 7.0 and 8.0 for strain RB10T. The growth rates
of both strains were higher in PY-BHI without NaCl,
but the organisms were halotolerant and grew in
medium containing 8% NaCl. These strains were
resistant up to 4 mM Cr(VI) and both were able to
reduce Cr(VI), although at different rates. After 15 h
growth in the presence of 2 mM Cr(VI) only strain RF6T
showed Cr(VI) reducing ability (0.06 mmol of Cr(VI)
reduced). Only strain RB10T was able to hydrolyze
gelatin and Tween 20, 40, 60 and 80. Cytochrome
oxidase was not detected in any of the organisms, but
catalase was positive in all strains. None of the strains
were able to ferment glucose. The organisms could be
distinguished from each other based on the carbohydrate
assimilation patterns on the API50 CH (Table 2).
Results