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

VL - 90

SP - 5032

EP - 5041

JO - Journal of Dairy Science

JF - Journal of Dairy Science

SN - 0022-0302

IS - 11

ER -