Enzymes produced by bacteria present on the surface of smear cheeses play essential
roles in flavour development during cheese ripening. In this study, strains including
brevibacteria, corynebacteria, staphylococci and brachybacteria, from the surface
of two smear cheese (Tilsit and Gubeen) were screened for a range of enzyme activities
including aminopeptidase (substrates: Leu-pNA and His-pNA), dipeptidase (Met-Ala,
Ala-Met, Pro-Ala, His-Leu and Pro-Leu), tripeptidase (Phe-Gly-Gly, Gly-Gly-Gly and
Leu-Ala- Pro), esterase (beta-naphthyl butyrate, beta-naphthyl caprate and beta-naphthyl
palmitate). L-methionine aminotransferase and cystathionine lyase activities. There
were marked differences in the activities observed between different bacteria studied.
Brachybacteria showed low activity on all substrates assayed. There was no consistency
in activities within groups of related bacteria. For example, Staphylococcus equorum
14 showed higher activity than S. equorum 6 on all the substrates tested. Among the
corynebacteria, Coryebacterium ammoniagenes CA8 had greatest aminopeptidase, esterase
and cystathionine lyase activity while C. casei B showed more di- and tri-peptidase
activity. It was noted that individual bacteria displayed similar activities on all
three esterase substrates, i.e., the chain length of the fatty acid did not appear
to affect activity. L-Methionine aminotransferase activity was observed in only one
strain (S. equorm 14) whereas all strains had cystathionine lyase activity.