The effect of temperature, pH, and salt concentration
of the incubation medium on enzyme activity has been
studied. Proteolytic activities of the three enzymes did
not differ at temperatures between 30-40 0c. Salt concentration
up to 30% had no effect on the 100 kDa enzyme.
Optimum pH for the 42 kDa enzyme was 7.0.
From these data, it is concluded that the proteolytic,
halotolerant, and moderately halophilic bacterium isolated
from fermenting fish sauce shares several properties
with species of the genus Halobacillus. For example,
sporulating cells were frequently observed in cultures
containing dividing cells, a significant amount of glycocalyx
was produced during growth in high salt media
and colony morphology was pleomorphic, with irregular
papillae formed at low salt concentrations (1 month).
It is concluded that strain f5-1 belongs to the genus
Halobacillus, but differs from the reference strains included
in this study in several respects. Strain fs-1 and H.
halophilus have proteolytic properties, whereas H.
litoralis and H. trueperi are not proteolytic. Strain fs-l
produced two serine proteases and a metalloprotease.
Substrate specificity of the proteases has not been determined
but, based on their response to specific ionic and
metal ion conditions, the isolate is versatile in protein hydrolysis.
One of the serine proteases showed undiminished
activity over a very wide range of NaCI concentration,
up to saturation (5M); the other serine proteases
were also active at high salt concentrations and the metalloprotease
proved unusual in its Ca++ dependency.