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Decarboxylase activity involved in methyl ketone production by Staphylococcus carnosus 833, a strain used in sausage
S Fadda1, A Lebert, S Leroy-Sétrin
1INRA Clermont Ferrand-Theix, Station de Recherches sur la Viande, 63122 Saint-Genès Champanelle, France.
Abstract:
Staphylococcus carnosus strain 833, inoculated into sausage, increased the levels of methyl ketones which contributed to the cured aroma. These ketones were predicted to arise from incomplete beta-oxidation followed by a decarboxylation. To check this hypothesis, we measured the beta-decarboxylase activity in resting cells of S. carnosus grown in complex or in synthetic medium, using as substrate a beta-ketoacid, which can be an intermediate of the beta-oxidation pathway. This activity was present throughout the growth period. The enzyme appeared to be constitutive because no induction was observed. High aeration, a pH of 5 and the presence of nitrate promoted the production of methyl ketones.