SQUALENE-HOPENE CYCLASE GENE OF ACETIC ACID BACTERIUM, ACETIC ACID BACTERIUM BRED WITH THE USE OF THE GENE, AND PROCESS FOR PRODUCING VINEGAR USING THE ACETIC ACID BACTERIUM

摘要

A novel acetic acid bacterium-origin gene participating in acetic acid-tolerance; a method of improving the acetic acid-tolerance of a microorganism, in particular, an acetic acid bacterium, using this gene; and a process of efficiently producing a vinegar having an elevated acetic acid concentration with the use of the acetic acid bacterium having the thus improved acetic acid tolerance. From a chromosomal DNA library of an acetic acid bacterium, a gene enabling the growth of the acetic acid bacterium in a medium containing acetic acid at such a high concentration as not allowing the growth in usual is obtained. By using this method, a novel gene participating in acetic acid-tolerance is cloned from an acetic acid bacterium for practical use belonging to the genus Gluconacetobacter. A transformant constructed by transferring this gene into an acetic acid bacterium has a remarkably improved acetic acid-tolerance. When this transformant is cultured under aeration in the presence of ethanol, the growth induction period is shortened and the growth speed and the acid-forming speed are elevated. Moreover, the final carryover acetic acid level thereof can be remarkably elevated thereby.