Of 10 strains of the purple non-sulfur bacterium
Rhodopseudomonas sphaeroides
, 8 acquired the ability to grow on
d
-(—)-tartrate; however, growth occurred only after extended lag phases ranging from 2 to 14 days. These lag phases occurred because only a small number of inoculum cells were able to grow by forming the enzyme
d
-(—)-tartrate dehydratase [
d
-(—)-tartrate hydro-lyase; EC number not yet available]. Once cells had grown on
d
-(—)-tartrate,
d
-(—)-tartrate dehydratase was formed constitutively. Therefore, mass cultivation of
R. sphaeroides
for production of large quantities of enzyme was possible on substrates much cheaper than
d
-(—)-tartrate. When 0.38 mol of
dl
-malate was used as a substrate in a chemotrophic fed-batch culture, a final biomass of 15 g (dry weight) liter
−1
and 1,500 U of
d
-(—)-tartrate dehydratase liter of culture
−1
were formed. The enzyme can be used for selective cleavage of racemic tartaric acid and for quantitative determination of
d
-(—)-tartrate.