Utilization ofd-tartaric acid bySalmonella paratyphi BandSalmonella java: comparison of anaerobic plate test, lead acetate test and turbidity test

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Abstract
D-Tartrate dehydrase of S. java is an O2-sensitive enzyme active in cultures incubated under the poorly aerated conditions of static culture but not in fully aerated shaken cultures nor on plates incubated aerobically. On plates of d-tartrate minimal agar incubated anaerobically the enzyme or the degradation products of d-tartrate are exported from d-tartrate-positive cells and are available to d-tartrate-negative bacteria. This may give misleading growth results when d-tartrate-positive and d-tartrate-negative strains are tested for growth on the same plate of d-tartrate minimal agar. The lead-acetate test terminated at 24 h, the 24 h turbidity test and the ability to grow on d-tartrate minimal agar within 48 h differentiated 53 S. paratyphi B strains that were negative in each of the 3 tests from 76 S. java that were positive in each of the tests. An intermediate group of 8 strains utilized d-tartrate in Difco bacto-peptone water to give a positive lead acetate reaction at 2 days, were stimulated to a varying degree by d-tartrate in Oxoid peptone water within the same period of incubation and grew poorly on d-tartrate minimal agar. These latter strains may be deficient in a permease controlling uptake of d-tartrate or export of d-tartrate dehydrase. Inability to utilize d-tartrate is unlikely to be the single character accountable for the reputed enhanced pathogenicity of S. paraptyphi B when compared with S. java. Indications for the existence of an enzyme, complementary to and mutually exclusive with d-tartrate dehydrase, that has a positive correlation with pathogenicity are discussed.