THE USE OF HYDROGEN AS A CHEMICAL PRE-REDUCTANT FOR AQUEOUS SULPHIDOGENIC MEDIA

The effective use of a 5% H-2-95% N-2 gas mixture, with a platinum cat alyst, as a pre-reducing agent for aqueous sulphidogenic media, is dem onstrated for Desulfovibrio desulfuricans, Desulfotomaculum nigrifican s, and Desulfobulbus propionicus. The use of H-2 has several advantage s over other chemical reductants such as Na2S, cysteine, sodium thiogl ycollate, and Ti (III) citrate. Hydrogen is nontoxic and noninhibitory to sulphidogenic bacteria, cannot act as a growth substrate, does not complex with or lead to the precipitation of other aqueous species pr esent in the medium, will be present in insufficient concentrations to serve as a significant energy source, and has significant laboratory safety advantages. The technique described has the additional advantag e of requiring only a simple, inexpensive gassing manifold, and will p rove to be of benefit to smalt laboratories which cannot afford the ex pense of purchasing an anaerobic chamber.