Reduccion del contenido de acidos nucleicos Saccharomyces cerevisiae (levadura panadera) por tratamiento termico

Abstract

The course of RNA degradation in yeast cells (S. cerevisiae) was checked using two methods: By measuring of ribose containing substances in the supernatant, and by checking the release of 14C substances from cells pulse labeled by 14C uracil. Various temperatures and. pH values of suspending medium with and without heat shock at higher temperatures were used. The leakage of protein during the treatment was also checked using Lowry's method and ninhydrin method. The releasing of RNA and proteins in the supernatant using heat shock (80°C, 1 minute, at 4.5 pH) following incubation at different temperatures (50, 60 y 70°C) show that there are not significant differences between 60 and 70°C for protein and nucleic acids, and the releasing is lower than for 50°C in both cases. The effectivity of RNA hydrolysis without heat shock was strongly dependent on pH of suspending media, showing a higher leakage at higher pH values . It was shown that the reduction of nucleic acids was higher without thermal shock. Differences between heat shock for 30 or 60 seconds were negligible. The percentage of protein leakage at several pH was between 17 to 24%, with the lowest value at the lowest pH. It was shown that there is a lineal relation between the % of dry matter of yeast and the nucleic acids released to the supernatant after heat shock treatment.