NATIVE PROMOTER-PLASMID VECTOR SYSTEM FOR HETEROLOGOUS CHOLESTEROL OXIDASE SYNTHESIS IN STREPTOCOCCUS-THERMOPHILUS

The cholesterol oxidase gene (choA) Of a streptomycete was used as a m odel for studying heterologous gene expression in Streptococcus thermo philus, an essential bacterium in dairy food fermentations. The vector s pER82 and pER82P were developed from the 2.2-kb indigenous plasmid ( pER8) of S. thermophilus ST108, and sP1, a 51-bp synthetic promoter pa tterned after a chromosomal sequence of S. thermophilus. The presence of sP1 promoter in pER82PbCOb with the choA insert aligned with the ca t gene was essential for the intracellular production of cholesterol o xidase. The pER82PbCOb was apparently stable in S. thermophilus with n o detectable evidence of deletion mutational events. (C) 1995 Academic Press, Inc.