Nucleic Acid and their Removal - Degration of nucleic acids produces uric acid, which may accumulate to damaging levels in humans since they do not possess uricase activity. It is therefore, necessary that nucleic acids be reduced to acceptably low levels especially in SCP intended for human use. In the rapidly proliferating microbial cells used for SCP, the bulk of nucleic acids are RNAs.

The level of RNA in SCP is reduced using one of the following methods:

(i) activation of endogenous RNases by, usually, a brief heat treatment, e.g., 20 min at 64°C reduces RNA from 10% to 1 % of dry weight in Fusarium graminearum SCP,

(ii) alkaline hydrolysis,

(iii) chemical extraction, and

(iv) suitable manipulation of growth and physiology of the microbial cells.