Figure 5From: Characteristics of a broad lytic spectrum endolysin from phage BtCS33 of Bacillus thuringiensisCharacterization of the endolysin PlyBt33. (a) Lysis of viable cells from five different Bacillus species and one E. coli strain by PlyBt33. Tests were carried out with a final protein concentration of 2 μM at 37°C in 20 mM Tris-HCl (pH 8.0). The initial OD600 of each strain suspension was 0.8. Crude extract of E. coli M15 containing pQE-30 was used as a control to treat B. thuringiensis strain HD-73. (b) pH-dependent activity of PlyBt33. Tests were carried out with a final protein concentration of 2 μM at 37°C in 20 mM Tris at varying pH levels. (c) Temperature-dependent activity of PlyBt33. Tests were carried out with a final protein concentration of 2 μM in 20 mM Tris-HCl (pH 8.0) at varying temperatures. (d) Temperature stability of PlyBt33. Proteins were first treated at different temperatures for 1 h and then the tests were carried out with a final protein concentration of 2 μM at 37°C in 20 mM Tris-HCl (pH 8.0). In (b), (c), and (d), decrease of OD600 (%) = (1− the absorbance of the bacterial suspension at the end of each treatment / the absorbance at the beginning of each treatment) × 100%.Back to article page