Recombinant Lactococcus starters as a potential source of additional peptidolytic activity in cheese ripening.
OBJECTIVE
The aim of this study was to modulate the lactococcal proteolytic system for enhancement of the cheese ripening process.


RESULTS
The genes encoding PepN, PepC, PepX and PepI peptidases of a highly proteolytic Lactobacillus helveticus strain were transferred into Lactococcus lactis in a food-grade cloning system. A comparison of the relative peptidase activities from the transformants with those from the untransformed host, determined in the conditions of maturing cheese, showed that an increase in peptidase activity could be achieved by introducing a selected peptidase gene from Lact. helveticus into L. lactis.


CONCLUSIONS
Recombinant L. lactis starter strains, carrying a peptidase gene from Lact. helveticus, may have an important contribution to the proteolysis of maturing cheese by producing an additional peptidolytic enzyme activity.


CONCLUSIONS
The results will be of importance in shortening the ripening period and production of special cheeses (e.g. reduced-fat cheeses) with improved characteristics.
Joutsjoki
V
V
MTT Agrifood Research Finland, Food Research, Jokioinen, Finland. vesa.joutsjoki@mtt.fi
Luoma
S
S
Tamminen
M
M
Kilpi
M
M
Johansen
E
E
Palva
A
A
D000626:Aminopeptidases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002611:Cheese / Q000382:microbiology*; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics / Q000378:metabolism*; D013294:Lactococcus lactis / Q000201:enzymology*; D010957:Plasmids; D011994:Recombinant Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic
D001426:Bacterial Proteins; D011994:Recombinant Proteins; C075633:pepN protein, Bacteria; D000626:Aminopeptidases; C022450:prolyl aminopeptidase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C098392:PepX dipeptidyl aminopeptidase; C080203:PEPC proteinase; D012697:Serine Endopeptidases