Serratia marcescens ATCC 21074로부터 돌연변이 유도에 의해 protease 생산능이 높은 ampicillin 耐性의 변이주 Serratia sp. SMNT-1을 분리하였다. 이 균주는 原 균주에 비하여 約 11배 정도 높은 protease 생산성을 나타내었다. 이 효소는 pH 9.0, $40^{circ}C$에서 최대 활성을 나타내었으며, 저온하에서는 pH 6.0-10.0 범위에서 안정하였으나, $37^{circ}C$, 알카리 조건하에서 불안정하였다. 이 효소는 $60^{circ}C$에서 10분간 열처리시 실활되었다.
A protease hyperproducer, ampicillin resistant mutant, Serratia sp. SMNT-1 was selected from Serratia marcescens ATCC 21074 by mutagenesis. The protease productivity of this strain was about 11 times as much as that of the parental strain. The enzyme showed maximal activity at pH 9.0 and $40^{circ}C$ and was stable over the pH range from 6.0 to 10.0 at $4^{circ}C$, whereas it was unstable at $37^{circ}C$ in alkaline condition. the enzyme was inactivated by heating at $60^{circ}C$ for 10 min. The enzyme was inactivated by EDTA and reactivated by $Zn^{2+}, Co^{2+},; and ; Mn^{2+}$, but the proteoiytic activity of the enzyme was not affected by DFP. From the above results, the protease produced by Serratia sp. SMNT-1 was classified as a metalloprotese.
