The lipolytic and esterase activities of fifteen strains of lactic acid bacteria isolated from different biotopes of Algeria and Mauritania were tested on MRS medium supplemented with lipidic substrates. Five of them showed maximum activity in the presence of tributyrin; the activity is therefore a tributyrin esterase. These strains were identified by MALDI-TOF in Enterococcus faecium and Enterococcus durans. The study of growth kinetics as a function of time shows a start of fatty acid production during the exponential phase to reach its maximum in the stationary phase. A better esterase activity is observed at between pH 6 and 9 and at an optimal temperature of 30 to 40°C for the five strains. The influence of metal and additive ions on the esterase activity varies between bacteria but generally, total inhibition was observed in all strains tested in the presence of SDS, NaN3, CuCl2, EDTA, AgNO3 and HgCl2.
Key words: Lipolytic activity, esterase activity, tributyrin, tributyrin esterase, MALDI-TOF, Enterococcus, growth kinetics, metal ions.