Method to isolate mutants and to clone the complementing gene

Abstract

The subject invention lies in the field of microorganism mutation and selection of the mutants. In particular, the invention is directed at obtaining metabolic mutants in a simple, direct and specific manner. In a preferred embodiment it is also possible to obtain desired mutants not comprising recombinant DNA, thereby facilitating incorporation thereof in products for human consumption or application, due to shorter legislative procedures. The method according to the invention involves random mutation and specific selection of the desired metabolic mutant. A nucleic acid cassette comprising a nucleic acid sequence encoding a bidirectional marker, said nucleic acid cassette further comprising a basic transcriptional unit operatively linked to the nucleic acid sequence encoding the bidirectional marker and said nucleic acid cassette further comprising an inducible enhancer or activator sequence linked to the basic transcription unit in such a manner that upon induction of the enhancer or activator sequence the bidirectional marker encoding nucleic acid sequence is expressed, said inducible enhancer or activator sequence being driven from a gene associated with metabolism is claimed as is application thereof in a selection method for mutants. In addition a regular gene xlnR encoding an activating regulator of an inducible enhancer or activator sequence and application of said gene and/or its expression product in overexpression of homologous or heterologous protein or peptide is described. Knockout mutants wherein said gene is absent or inactivated and mutants with increased or decreased DNA binding capacity are also claimed.

Dependencies are inferred from the claim text.