Adaptation of Rhodopseudomonas sphaeroides to Growth on d -(—)-Tartrate and Large-Scale Production of a Constitutive d -(—)-Tartrate Dehydratase During Growth on dl -Malate

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 and 1,500 U of d-(-)-tartrate dehydratase liter of culture were formed. The enzyme can be used for selective cleavage of racemic tartaric acid and for quantitative determination of d-(-)-tartrate.