Cell Structure and the Enzymic Lysis of Bacteria

摘要

SUMMARY: Untreated cells of three Gram-negative and four Gram-positive bacteria were resistant to lysis by crude and crystallbe trypsin. The resistance of the Gram negative organisms to lysis by trypsin was abolished by heating suspensions for 5 min. at 100°; the rates and extent of lysis of the three organisms by crude trypsin were comparable. After maximal lysis of heated suspensions of Bacterium coil and Pseudomonas fluorescens, by crude trypsin, examination of the residual material in the electron microscope showed that cel walls were the principal components. When heated suspensions of Micrococcus lysodeikticus, Bacillus megaterium and Staphylococcus aurm were incubated with crude or crystalline trypsin, slow lysis occurred and the extent of lysis was less than that observed for the Gram-negative bacteria. Electron microscopic examination of trypsin-lysed cells of B. megMum showed incomplete digestion of cytoplasmic contents. Heated and autochved cells of Streptococcus faecalis were resistant to digestion with trypsin.Cell-wall suspensions of B. meguterium were rapidly lysed on incubation with crystalline lysozyme. Heated cells of M. lysodeikticus were only partially lysed by lysozyme, but the subsequent addition of trypsin resulted in a rapid dissolution of the cell bodies. Although treatment of heated B. megaterium cells with lysozyme resulted in turbidity increases, the enzyme completely digested the cell wall leaving coagulated protoplasmic bodies. The protoplasmic bodies were rapidly lysed by crude trypsin.