New mutant lactic acid bacterium, useful for preparation and maturation of cheese, has negative regulatory factor inactivated so overexpresses peptidase

摘要

Mutant lactic acid bacterium (A) that overexpresses one or more peptidases (I) and has at least one negative regulatory factor (B) for at least one (I)-encoding gene (II) inactivated. (B) is the codY gene, genes of the lev operon or a gene that encodes a beta -glucosidase homologue. Independent claims are also included for the following: (a) recombinant vector (RV) for identifying and selecting (A) comprising a marker gene (III) fused to (II), or its promoter, an origin of replication that is inactivated after integration into a bacterium, an antibiotic marker and part of the cluA gene; and (b) identifying and selecting of (A) by conjugation with RV, growing transformants in presence of peptides, and measuring activity of (III).