[The effect of various culture parameters on the yield of restriction endonuclease Sfa NI].

A simple technique is proposed for testing the restriction endonuclease Sfa NI activity in lysates of Streptococcus faecalis cells. The technique was used to study the effect of inorganic phosphate and the growth phase on the enzyme yield. Conditions were chosen that provide a high yield of the Sfa NI activity and a significantly reduced level of nucleases in the cells.