Expression of Streptomyces sp. cholesterol oxidase in Lactobacillus casei

Abstract

Three strains of Lactobacillus casei were electrotransformed with pNCO937, an 8.1-kb recombinant plasmid carrier of a Streptomyces sp. cholesterol oxidase gene. Transformation frequency was generally low and strain-dependent, ranging from 6 to 40 transformants/μg DNA. L. casei transformants stably maintained pNCO937 with no indication of deletion mutational events. Transformants produced active cholesterol oxidase and sonicated cells formed 4-cholesten-3-one from both free and lipoprotein-bound cholesterol. L. casei shows promise as a host suitable for studying heterologous gene expression in lactobacilli.