The proteolytic capacity of 36 strains of the genus Rhizopus isolated
from Indonesian tempe or tempe inocula was examined. No significant ch
anges in the total amount or pattern of amino acids could be found, bu
t there was a distinct increase in the amount of free amino acids. Str
ains with a high proteolytic activity were found, which were able to r
elease nearly five times more amino acids after standard fermentation
than others. Changes in fermentation parameters such as temperature or
relative humidity improved these results. Fermentations with mixed po
pulations of bacteria and Rhizopus yielded a lower level of free amino
acids, but an increased total amount of an,ino acids. Examination of
protease systems of three Rhizopus species showed that the proteases o
f the cell wall fraction were most responsible for proteolytic capacit
y of the different strains. On average their activity amounted to 71%
of the total proteolytic capacity.