Quantification of the Growth Competition of Lactic Acid Bacteria: a Case of Co-culture with Geotrichum candidum and Staphylococcus aureus
Department of Nutrition and Food Assessment, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava, Slovak Republic
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Abstract: The work turns the attention to the growth of two microorganisms which are connected with fermentation and contamination of artisanal lump cheeses. The effect of the cultivation temperature and the presence of Fresco culture on the growth of yeast-like microorganism Geotrichum candidum and on Staphylococcus aureus, the bacterial toxin producing cheese contaminant in ultrapasteurized milk was studied. The culture Fresco with initial concentration from 106 to 107 CFU.ml-1 significantly inhibited growth of both microorganisms. The growth rates of G. candidum and S. aureus were lower and the lag-phase duration was prolonged in comparison with the data resulted from growth in mono-culture. At all tested temperatures the counts of the Fresco culture observed in stationary phase ranged between 108 CFU.ml-1 and 109 CFU.ml-1, whereas maximal density of G. candidum in stationary phase was around 105 CFU.ml-1 and S. aureus grew up only about 0.3 to 0.6 logs with maximal density about 104 CFU.ml-1. The growth data found in this work may provide the information basis for food technologists and microbiologists to get the studied organism under the control. This is naturally important, however, each of the organisms play a different role during cheese fermentation.
Keywords: Geotrichum candidum, lactic acid bacteria, predictive modelling, Staphylococcus aureus
Full paper in Portable Document Format: acs_0018.pdf
Acta Chimica Slovaca, Vol. 1, No. 1, 2008, pp. 192—201