Studies On The Release And Recovery Of 5'-Monophosphonucleotides From Yeasts

A study of the parameters such as pH, glucose concentration and residual nitrogen content influencing the build up of 5'-monophosphonucleotides of Saccharomyces cerevisiae "No. 56" has been carried out. An investigation into cell size, budding stage and release of cytoplasmic constituents of Saccharomyces cerevisiae Distillers M during its replenishment in various media was carried out. Results have shown that maximum cell size occurred after a defined period (2 hours) at which time budding had commenced and relatively high concentrations of 5'-monophosphonucleotides were found. Release (shock excretion) of cytoplasmic constituents was investigated as a function of time using glucose. An initial 30 minute starvation of the yeast cells following by a 90 minutes shock excretion, was found to be the optimum time for the release of 5'-monophospho nucleotides. A sucrose fatty acid ester used as a shock excretion agent, was found to be more efficient than glucose, and ensured retention of a high viability of the yeast cells when used in a 20 litre continuous tower fermenter System. Using this equipment a continuous process, has been developed for the repeated release and recovery of (iv) cytoplasmic constituents rich in 5'-monophosphonucleo tides from yeast cells, which comprises: 1) contacting the yeast cells with a solution of a sucrose fatty acid ester. 2) separating the yeast cells from the released cytoplasmic constituents. 3) supplying the yeast cells with fresh medium to allow restoration of the level of 5'-monophospho nucleotides to the level required for shock excretion as in 1). The work has resulted in the development of a high-performance liquid chromatographic method for the analysis of 5'-monophosphonucleotides, AMP, CMP, TMP, IMP, UMP and XMP in the cytoplasmic constituents of the yeast cells. Organoleptic comparison of the freeze-dried cytoplasmic constituents produced during this study with commercially available material has been used.