<p>A method for gene expression is carried out by transforming a genome with a target gene under the control of a gene promoter present with an auto-regulatory mechanism, and which is not required for the growth or fermentation of the host organism. Independent claims are also included for: (1) a promoter containing a DNA of: (a) a DNA with a base sequence of (I) of 971 base pairs; (b) a DNA derived from the sequence of (I) but with 1-40 bases deleted, substituted or added and having promoter activity; or (c) a DNA hybridizable with a DNA complementary with the whole or a part of the base sequence under stringent conditions; (2) a recombinant vector containing the promoter; (3) a transformant which is transformed with the recombinant vector; and (4) a process for producing an expression product of the target gene or a substance from such expression product by culturing the transformant before isolation from the cultured material.</p>
