RECOMBINANT PLASMIDS; BACTERIA CONTAINING SUCH RECOMBINANT PLASMIDS; PROCESS FOR PREPARING FERMENTED FOOD PRODUCTS, ANIMAL FEEDSTUFFS, INGREDIENTS THEREOF OR PROTEINS USING SUCH BACTERIA

摘要

The cryptic Streptococcus cremoris Wg2 plasmid pWV01 (1.5 Md) was genetically marked with the chloramphenicol resistance (CmR) gene from pC194, the erythromycin resistance (EmR) gene from pE194 cop-6, the chloramphenicol acetyl transferase (CAT) gene, or combinations thereof to provide recombinant vector plasmids which can replicate in B. subtilis, E. coli and lactic streptococci. The Cm?R and EmR¿ genes were expressed under regie of their own promoters, whereas the CAT gene was expressed under regie of the b. subtilis SPO2 promoter. Instead of antibiotic resistance markers, the use of auxotrophic markers, e.g. the genes for lactose metabolism, is envisaged. Moreover, other genes were inserted into these plasmids and expressed in Streptococcus lactis, namely the bovine prochymosin gene described in EP-PA 0 077 109 (A2) under regie of B. subtilis SPO2 promoter and the protease gene(s) from Streptococcus cremoris Wg2 plasmids pWV05. These and similar plasmids can be used to transform lactic acid bacteria to provide them with improved or new properties for the use in the fermentative preparation of food products, animal feedstuffs and ingredients thereof, as well as of proteins. A method for isolating other protease genes is provided which can be used instead of the pW05-derived protease gene(s).