Culture of Desulphovibrio desulphuricans

Abstract

IN a discussion about the method proposed by us¹ for the counting of sulphate-reducing bacteria in mixed population, Dr. J. R. Postgate pointed out in correspondence that, if one is handling a natural sample in which the population of sulphate-reducing bacteria out-numbers that of other micro-organisms, then the higher dilutions of such a sample are effectively pure cultures. Evaluation of our method with pure cultures of D. desulphuricans was obviously indicated. Dr. Postgate kindly furnished us with lyophilized pure cultures of the freshwater strain Hilden-borough (N.C.I.B. 8303) and the salt-water strain El Agheila Z (N.C.I.B. 8380) of D. desulphuricans. Our experience in the culturing of both strains from the desiccates is summarized in Table 1; an iron nail in the medium clearly obviates difficulties in the revival of lyophilized cultures and, in addition, makes the exclusion of oxygen unnecessary. In a medium containing a nail, cysteine did not appear to be essential although it promoted earlier growth.