at an industrial level this method is useful to modify several genetic loci in clostridia in a routine manner this method is based on a replicative vector carrying at least two marker genes application_number US 82397810 A description the invention provides a process for the stable interruption of a target gene in a strain of the type clostridia comprising an origin of replication functional in clostridia a first marker gene a second marker gene one or more group ii intron sequences a reverse transcriptase encoding gene ii selecting strains having integrated said replicative vector that express the second marker gene iii selecting strains having an interrupted gene following the integration of the intron sequence into said gene iv optionally culturing the selected strains to obtain their evolution toward a state wherein they are able to survive with the interrupted gene v selecting strains having eliminated said replicative vector that do not express the first and the second marker genes all molecular biology techniques used for realizing the invention are fully described in lt lt molecular cloning a laboratory manual gt gt 2 nd edition cold spring harbor laboratory press 1989 by sambrook fritsch and maniatis used in the context of the present invention the term lt lt interruption gt gt of a target dna sequence means that a sequence is introduced at the locus of the target dna sequence the expression u201c stable interruption u201d means that the interruption of the gene will stay into the strain for at least 50 generations and even more according.