TY - JOUR
T1 - Ammonia production and its possible role as a mediator of communication for Debaryomyces hansenii and other cheese-relevant yeast species
AU - Gori, Klaus
AU - Mortensen, Henrik Dam
AU - Arneborg, Nils
AU - Jespersen, Lene
PY - 2007
Y1 - 2007
N2 - Ammonia production by yeasts may contribute to an increase in pH during the ripening of surface-ripened cheeses. The increase in pH has a stimulatory effect on the growth of secondary bacterial flora. Ammonia production of single colonies of Debaryomyces hansenii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Geotrichum candidum was determined on glycerol medium (GM) agar and cheese agar. The ammonia production was found to vary, especially among yeast species, but also within strains of D. hansenii. In addition, variations in ammonia production were found between GM agar and cheese agar. Ammonia production was positively correlated to pH measured around colonies which suggests ammonia production as an additional technological parameter for selection of secondary starter cultures for cheese ripening. Furthermore, ammonia appeared to act as a signaling molecule in D. hansenii s reported for other yeasts. On GM agar and cheese agar, D. hansenii showed ammonia production oriented toward neighboring colonies when colonies were grown close to other colonies of the same species; however, the time to oriented ammonia production differed among strains and media. In addition, an increase of ammonia production was determined for double colonies compared with single colonies of D. hansenii on GM agar. In general, similar levels of ammonia production were determined for both single and double colonies of D. hansenii on cheese agar.
AB - Ammonia production by yeasts may contribute to an increase in pH during the ripening of surface-ripened cheeses. The increase in pH has a stimulatory effect on the growth of secondary bacterial flora. Ammonia production of single colonies of Debaryomyces hansenii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Geotrichum candidum was determined on glycerol medium (GM) agar and cheese agar. The ammonia production was found to vary, especially among yeast species, but also within strains of D. hansenii. In addition, variations in ammonia production were found between GM agar and cheese agar. Ammonia production was positively correlated to pH measured around colonies which suggests ammonia production as an additional technological parameter for selection of secondary starter cultures for cheese ripening. Furthermore, ammonia appeared to act as a signaling molecule in D. hansenii s reported for other yeasts. On GM agar and cheese agar, D. hansenii showed ammonia production oriented toward neighboring colonies when colonies were grown close to other colonies of the same species; however, the time to oriented ammonia production differed among strains and media. In addition, an increase of ammonia production was determined for double colonies compared with single colonies of D. hansenii on GM agar. In general, similar levels of ammonia production were determined for both single and double colonies of D. hansenii on cheese agar.
KW - Former LIFE faculty
KW - Debaryomyces hansenii, ammonia production, signaling, cheese
U2 - 10.3168/jds.2006-750
DO - 10.3168/jds.2006-750
M3 - Journal article
C2 - 17954742
SN - 0022-0302
VL - 90
SP - 5032
EP - 5041
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 11
ER -