SDS-PAGE and zymogram analysis of purified yeast-expressed bacteriophage endolysins. (a) SDS-PAGE of yeast-expressed LysA and LysA2 purified using Ni-NTA chromatography. Lane 1, 3 Precision Plus standard; Lane 2, 2.5 μg LysA (predicted MW = 37.9 kDa); Lane 4, 2.5 μg LysA2 (predicted MW = 41.1 kDa). (b) Zymogram analysis with whole cells of L. fermentum 0605-B44 co-polymerized within the polyacrylamide gel. Endolysin exolytic activity resulted in visible clearing (dark bands indicated by black triangles) of the cell substrate at the point of protein localization, which corresponds with the predicted and observed molecular weights.