Abstract: A new approach for targeting chemotherapeutics to focal bacterial infections is provided. Such focal infections are characterized by high densities of different bacteria and thus high concentrations of their extracellular signal molecules sensing the cell density. In gram-negative bacteria, one of such signal molecules is acyl-homoserine lactone (acyl-HSL, member of the autoinducer family AI-1), wherein species-specificity is achieved by acyl-residues, and HSLs are common for all gram-negative bacteria. In gram-positive bacteria, oligopeptides secreted by the bacteria communicate the cell density. In addition, there are cell density signal molecules (members of the autoinducer family AI-2) which communicate between gram-positive and gram-negative bacteria. The general scheme of the present invention is molecular modules that comprise both a targeting component and a chemotherapeutical component which serves for photodynamic antimicrobial chemotherapy (PACT).

Abstract: The invention relates to a fed-batch fermentation process which uses special E. coli host/vector systems for the purpose of efficiently forming recombinant proteins, in particular recombinant antibody molecules, preferably antibody fragments such as miniantibodies. Under the given conditions, the E. coli cells are able to grow at a maximum specific growth rate up to very high cell densities. After the recombinant product formation has been switched on, it is only the formed product which restricts growth; there is no growth restriction due to substrates or metabolic by-products. High space-time yields of recombinant proteins can be achieved in this manner.