Optimal production conditions of Streptomyces griseus trypsin (SGT) in Streptomyces lividans

The sprT gene encoding Streptomyces griseus trypsin (SGT) was introduced into Streptomyces lividans TK24 and Streptomyces lividans 1326 to study which strain would be better to overexpress the extracellular proteinase, Various media with different compositions were also used to maximize the productivity of SGT in heterologous hosts. The SGT productivity was best when the transformants of S. lividans TK24 and 1326 were cultivated in R2YE medium, and their relative trypsin activity of the culture broth measured with an artificial chromogenic substrate, N-alpha-benzoyl-DL-arginine-rho-nitroanilide, were 382 units/ml and 221 units/ml, respectively. They produced high levels of SGT in GYE medium but relatively lower than those in R2YE medium, and negligible amount of SGT was produced in Perm, RASF, LIVLD, and NDSK media. Considering non-SGT associated activity in Pronase powder, it was estimated that the transformant of S, lividans TK24 can produce SGT in R2YE 3.5 times more than the amount by S, griseus 10137 from which the sprT gene had been originated, The growth of S, lividans reached the maximum level of cell mass at 5 d of culture, but SGT production started in the stationary phase of cell growth and kept increasing until the ninth day of culture in R2YE medium, but in GYE media the productivity reached at the maximum level at 7 d of cultivation.