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

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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.

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