INFLUENCE OF ECOLOGICAL PARAMETERS ON THE COMPETITIVENESS OF L-PENTOSUS AND L-SAKEI

The determination of the ecological parameters concerning the growth o f lactic acid bacteria is of great importance for the selection and th e secure use of starter cultures. Therefore, weakly competitive organi sms were compared to highly competitive ones in a liquid modell system featuring conditions derived from those prevailing in fermented sausa ge. The yield and maintenance coefficient was investigated as well as the direct competition of lactobacillus (L.) sakei LTH681 and L. pento sus LTH958. In addition, the adaptation behavior to low temperature (2 2,5 degrees C) and high salt concentration (5%) was elucidated for L. sakei LTH681. The highly competitive L. sakei LTH681 showed a higher c ellmass production rate at lower growth rates as compared to its compe titor. The maintenance coefficient of L. pentosus LTH958 was 73% highe r than that one of L. sakei LTH681 under conditions resembling sausage fermentation. Therefore, L. pentosus LTH958 was not able to directly compete against L. sakei LTH958. The mixed cultures hardly showed repr oduction of L. pentosus LTH958. Adaptation to the conditions mentioned above always led to a significantly shortened lag-phase. The competit ive advantage compared to non-adapted cells could be conserved by mean s of freezing. Information was obtained about the competition of start er cultures providing data for highly and weakly competitive lactic ac id bacteria. This knowledge concerning the ability of a strain to cont rol sausage fermentation represents an important contribution to the i mprovement of the quality control of this process.