Vectors that facilitate the replacement of transcriptionallacZfusions inStreptococcus mutansandBacillus subtiliswith fusions togfporgusA

Plasmid vectors have been constructed for Streptococcus mutans and Bacillus subtilis that make possible rapid replacement of the widely used reporter gene lacZ (encoding beta-galactosidase) with either gfp (encoding green fluorescent protein) or gusA (encoding beta-glucuronidase). The lacZ-->gfp replacement vectors greatly facilitate the analysis of the spatial location of gene expression in biofilms of S. mutans and in sporulating B. subtilis. The lacZ-->gusA replacement vectors facilitate the comparison of two promoters within the same organism. A vector is also described that enables gusA to be replaced with gfp in B. subtilis.