Production of Hydrogen Sulfide from Sulfur-Containing Compounds by Various Bacteria. II. Experiments with Synthetic Medium

Abstract

Summary

1. Production of hydrogen sul-fide by E. coli, K. pneumoniae, B. subtilis, and P. aeruginosa in synthetic media containing cysteine or methionine and their derivatives was studied. 2. With the exception of P. aeruginosa, all these organisms formed moderate to maximal amounts of hydrogen sulfide from cysteine and cystine. P. aeruginosa produced only traces.

3. Only K. pneumoniae produced hydrogen sulfide from N-benzoyl-cysteine. This confirms previous observations made with beef infusion agar basic medium.1 Benzoylation of the alpha amino group of cysteine does not interfere with desulfurization by this organism, although it prevents the reaction in the case of other bacteria studied. This indicates fundamental metabolic differences prevailing in the organisms investigated with respect to this particular reaction. Additional strains of K. pneumoniae and other organisms should be tested under similar conditions.

4. None of the organisms formed hydrogen sulfide or mercaptan from S-benzyl-cysteine, in contrast to the results obtained when this substance was added to beef infusion agar. Hydrogen sulfide was not produced by any of the bacteria from cysteic acid, methionine, S-benzyl-homocysteine, or homocystine. 5. A limited number of observations on pigment formation by P. aeruginosa in the presence of cysteine, methionine, and their derivatives was made.

6. A strain of K. pneumoniae continued to produce large capsules and maintained high virulence for mice after many transfers in a simple synthetic medium.