Abstract

Growth medium components and cultivation conditions for the extremely thermophilic Archaea Thermococcus celer and Pyrococcus woesei were optimized. A culture media based in marine water was formulated. Both Archaea demonstrated to be strictly anaerobic with optimal growth temperature of 85°and 95°C, respectively. Sodium sulfide, but not cysteine, was used as a sulfur and reductive capacity source. It was observed that hydrogen sulfide could be replaced by 30 ?M titanium (III) nitrile acetate. The addition of elemental S°enhanced growth of both microorganisms, with T. celer far more sensitive than P. woesei to the absence of S°. P. woesei utilized maltose as a carbon source, while T. celer was able to use only peptides from yeast extract, peptone and tryptone as its carbon source. Optimum carbon source concentrations were 1.25 g/L for T. celer and 5 g/L for P. woesei. Although both Archaea required peptides as a nitrogen source, the addition of ammonia chloride to a nitrogen-limited media did not stimulate growth, which suggests that neither Archaea appear to metabolize ammonia. The growth of P. woesei, but not T. celer, was stimulated considerably in the presence of iron. Co, Ni, Zn, Mo, Mn and Mg were essential trace elements needed for optimal growth of both bacteria.