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

Article history:
Received June 19, 1995 
Accepted July 28,1995

Summary:
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 (1^st step pH = 4.9; 2^nd 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%.