Agency of Industrial Science and Technology

Ministry of International Trade & Industry

Extra Ministerial Bureau of Ministry of International Trade and Industry

Akiko Akaoka

Masaru Honjo

Yoshio Furutani

Akira Nakayama

Hiroaki Shimada

Izumi Mita

Koichi Kawamura

Kouichi Kawamura

Residual extracellular protease activities of a Bacillus subtilis strain can be further reduced by introducing a gene for the stimulation of extracellular protease levels into the genomic DNA of the strain. The resultant strain whose extracellular protease activities are further reduced is transformed with a recombinant plasmid for secretion of a desired protein and the desired protein can be efficiently produced and accumulated in the culture medium in a large amount. The accumulated desired protein can be easily recovered from the culture medium. For example, the accumulation level of human growth hormone secreted by a B. subtilis MT-430 strain carrying recombinant DNA phGH427 for the expression and secretion of human growth hormone can be increased five to tenfold as a result of the above treatment for reduction of the residual extracellular protease activities of the extracellular protease-activity-deficient strain.

Bacillus subtilis strain whose extracellular protease activities are

A expression-secretion vector is constructed by using a DNA sequence comprising a DNA fragment obtained by subjecting a DNA sequence consisting of a region involved in the expression of a gene coding for an extracellular enzyme of a bacterium of the genus Bacillus and a region involved in the secretion of the enzyme thus expressed to a deletion in the region involved in the secretion which can enhance the extracellular production of a protein dependent on the DNA fragment. By transforming a host bacterium with a recombinant DNA molecule formed by inserting a DNA fragment comprising a gene coding for a desired protein into the expression-secretion vector and then culturing the transformed host, the extracellular production of the desired protein in a large amount can be accomplished.

DNA sequence involved in gene expression and protein secretion,

Growing community of inventors

Mobara, Japan

Akiko Akaoka