Figure 3
The activities of lysine decarboxylase in E. tarda. A TX01, TX01ΔcadA, TX01ΔcadB, TX01ΔcadBA, TX01ΔcadAC, and TX01ΔcadBC were cultured in lysine decarboxylase broth with lysine in static condition at 28 ℃ for 10, 20 and 30 h, respectively. A light purple indicates a weak positive result. Purple and yellow indicate the presence and absence of LDC, respectively. B The same strains were cultured in LB broth to an OD600 of 0.5 and normalized to an OD600 of 1.0, buffered at pH 6.8. The activities of lysine decarboxylase were determined as described in the text. The experiment was performed three times, data are presented as the means ± SEM (N = 3). N, the number of times the experiment was performed. **, P < 0.01.