Abstract: A process for preparing lactic acid bacterial starter cultures, which comprises: culturing at least one strain of lactic acid bacteria under aeration and in an appropriate nutrient medium, in which at least one porphyrin compound is present or is added; harvesting the bacteria at the end of said culture. A method of using lactic acid bacterial starter cultures obtained according to said process for preparing a fermented product.

Abstract: The invention relates to a promoter inducible by metalloporphyrins. Said promoter is useful for controlling the expression of genes of interest in gram-positive bacteria deficient in heme biosynthesis, in particular lactic acid bacteria.

Abstract: The invention relates to a method for eliminating a biofilm of microorganism preexisting on an inert surface, characterized in that one subjects said biofilm to a cocktail of microorganisms comprising at least strains said to be “swimming” able to cross said biofilm in the plane and in the thickness, and one subjects said biofilm to at least one antimicrobial product directed against at least one microorganism of the biofilm to be eliminated.

Abstract: The invention concerns bacteria strains, obtained from gram-positive bacteria whereof the genome size is not more than 3.2 Mb, and wherein the HtrA surface protease is inactive. Said strains are useful for expressing exported proteins of interest.

Abstract: The invention concerns bacteria strains, obtained from gram-positive bacteria whereof the genome size is not more than 3.2 Mb, and wherein the HtrA surface protease is inactive. Said strains are useful for expressing exported proteins of interest.

Abstract: A process for preparing lactic acid bacterial starter cultures, which comprises: culturing at least one strain of lactic acid bacteria under aeration and in an appropriate nutrient medium, in which at least one porphyrin compound is present or is added; harvesting the bacteria at the end of said culture. A method of using lactic acid bacterial starter cultures obtained according to said process for preparing a fermented product.

Abstract: A bacterial vector plasmid of the type having an efficient replication origin in Gram-positive bacteria. The plasmid is characterized by having at least one marker gene which expresses itself in a bacterial host strain, an efficient replication system which is thermosensitive based on a temperature compatible with the viability of the host strain, and in that the temperature of replication inhibition is below or equal to approximately 37.degree. C. The invention also concerns bacteria containing the plasmid and a process for inactivating a gene in the chromosome of a bacterium.

Abstract: A method for the inactivation of a gene in a bacterium or for the introduction of a heterologous gene into a bacterium comprises a) introducing, by transformation or conjugation, in the bacterium a bacterial vector plasmid comprising a marker gene capable of being expressed in a bacterial host strain and an effective replication system which is temperature sensitive at and above a temperature compatible with the viability of the host strain; b) culturing the bacterium on a selective medium at a temperature below the temperature of inhibition to form a culture; c) raising the temperature of the culture to a temperature above the temperature of inhibition; and d) recovering the surviving bacteria after several multiplication cycles.