Optimization of the RNA Content Reduction i/i Saccharomyces cerevisiae
Sunčica Beluhan and V. Marić
Faculty of Food Technology and Biotechnology, University of Zagreb, Croatia
Received June 19, 1995
Accepted July 28,1995
Yeast as a source of protein for human consumption is limited by its relatively high nucleic acid content. In this work we have studied the problem of RNA extraction in yeast Saccharomyces cerevisiae (fresh baker's yeast) by optimization of the concentration of alkali solution (NH4OH). Extractions with 5, 10 and 15 % of NH4OH (referring to yeast dry matter) were performed for 15 minutes at 45-80 ºC (step 5 ºC measuring losses of protein and biomass and percent of nucleic acid reduction. With relatively loiv mass ratio (10 % NH4OH) at 60 °C, a final RNA content of 1.73 % was obtained after an extremely reduced extraction lime of only 15 minutes. After the extraction procedure, RNA was recovered by fractional precipitation lowering pH (1st step pH = 4.9; 2nd step pH = 2.0) by addition of HCI. Two solid fractions were obtained and RNA content in the precipitates was analyzed. The yield of RNA (g RNA obtained per g RNA in native yeast) in the second precipitate was 72.1 %. Purity of the second precipitate was 69.7%.