HISTIDINE-DECARBOXYLASE ACTIVITY OF LEUCONOSTOC-OENOS-9204

Some bacteria are able to produce histamine from histidine via an enzy me: histidine decarboxylase (HDC). This biogenic amine may be responsi ble for vasomotor and digestive disturbances. In food such as fish mea t or fermented products such as sauerkraut, cheese, fermented sausages and wines, bacteria can produce histamine. Recently, Lonvaud-Funel an d Joyeux isolated a strain of Leuconostoc oenos (Leuc. oenos 9204), wh ich is the species mainly responsible for malolactic fermentation in w ines. We have studied the enzymatic activity on cell suspensions and c ell-free extracts. At pH optimum 4.8, the HDC activity exhibited a Mic haelis-Menten kinetic (Km=0.34 mmol l(-1), V-max=89.35 nmol/min/mg), w hile at pH 7.6 a sigmoidal kinetic was observed. Histamine competitive ly inhibited the enzymatic activity with a Ki value of 50 mM. The effe cts of different compounds encountered in wines were also investigated . A high ethanol concentration (12%) reduced the enzymatic activity of cell suspensions and did not affect the activity of the cell-free ext ract. L-lactic acid and citric acid inhibited both, whole cells and ce ll-free extract. (C) 1995 Academic Press Limited