A gene encoding β-glucanase activity fromBacillus amyloliquefacienswas subcloned in both orientations into plasmid shuttle vector pSA3. In only one orientation could a co-integrate be generated with the conjugative plasmid pVA797. The plasmid co-integrate was conjugated intoLactobacillus helveticusstrain CNRZ450, where it was stably maintained without antibiotic selection and exhibited β-glucanase activity. This method of introducing cloned DNA into thermophilic lactobacilli will facilitate the study of heterologous gene expression in non-transformable specie
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