Modelling the growth of Weissella cibaria as a function of fermentation conditions

Aims: To investigate the effect of pH, water activity (a(w)) and temperature on the growth of Weissella cibaria DBPZ1006, a lactic acid bacterium isolated from sourdoughs. Methods and Results: The kinetics of growth of W. cibaria DBPZ1006 was investigated during batch fermentations as a function of pH (4 center dot 0-8 center dot 0), a(w) (0 center dot 935-0 center dot 994) and temperature (10-45 degrees C) in a rich medium. The growth curve parameters (lag time, growth rate and asymptote) were estimated using the dynamic model of Baranyi and Roberts (1994. A dynamic approach to predicting bacterial growth in food. Int J Food Microbiol23, 277-294). The effect of pH, a(w) and temperature on maximum specific growth rate (mu(max)) were estimated by fitting a cardinal model. mu(max) under optimal conditions (pH = 6 center dot 6, a(w) = 0 center dot 994, T = 36 center dot 3 degrees C) was estimated to be 0 center dot 93 h-1. Minimum and maximum estimated pH and temperature for growth were 3 center dot 6 and 8 center dot 15, and 9 center dot 0 degrees C and 47 center dot 8 degrees C, respectively, while minimum a(w) was 0 center dot 918 (equivalent to 12 center dot 2% w/v NaCl). Conclusions: Weissella cibaria DBPZ1006 is a fast-growing heterofermentative strain, which could be used in a mixed starter culture for making bread. Significance and Impact of the Study: This is the first study reporting the modelling of the growth of W. cibaria, a species that is increasingly being used as a starter in sourdough and vegetable fermentations.