| 摘要 |
<p>The invention relates to DNA fragments containing at least one 'mutant protease gene', which 'mutant protease gene' is understood to mean: a gene made up of sections of parent protease genes of several lactococcal strains, in particular of the parent protease genes of L.lactis subsp. cremoris Wg2 and L.lactis subsp. cremoris SK11, as well as a parent protease gene of a lactococcal strain, in particular the parent protease gene of L.lactis subsp. cremoris Wg2 or the parent protease gene of L.lactis subsp. cremoris SK11, the DNA sequence of which has been altered in a manner such that in the mutant protease for which the gene codes: (a) an amino acid other than that of the 'wild-type' protease is present at at least one site, and/or (b) at at least one site within the first 1350 residues of the amino acid sequence, calculated from the N-terminus, at least one amino acid of the 'wild-type' protease is missing and/or one or more amino acids have been inserted, or (c) at at least two sites separated from each other, one or more amino acids are missing and/or one or more amino acids have been inserted, the cloning vectors containing such a DNA fragment, the transformed host strains containing such a DNA fragment or vector, the mutant proteases obtainable as well as the foodstuffs and flavourings produced with the host strains or mutant proteases meant above.</p> |
