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The effects of phagocytosis and killing on microbial structural integrity have not been well defined. Recently we have presented evidence suggesting that rapid killing of Escherichia coli in vitro by intact or disrupted rabbit polymorphonuclear leukocytes occurs without major structural disorganization (1, 2). This conclusion was based on the findings that: (a) degradation of structural constituents such as lipids and peptidoglycans was limited, (b) macromolecular synthesis, including the induction of/~-galactosidase continued after more than 95 % of the E.coli could no longer divide, (c) the killed E.coli population retained its ability to "step-up" macromolecular synthesis in response to enrichment of the medium with simple nutrients (3), and (d) by contrast, under identical conditions other microorganisms, such as gram-positive Micrococcus lysodeikticus and Bacillus megaterium, underwent more rapid and extensive destruction of envelope constituents and within minutes lost biosynthetic activity (i).This report concerns further studies on the effects of granulocytes on the envelope of E.coli. The results support our contention that killing of E.coli by granulocytes is not linked to general structural disruption. However, killing by granulocytes and purified fractions prepared from granulocytes is temporally closely related to an increase in permeability. Some of the properties of the activity in disrupted granulocytes that causes this permeability change in E.coli and certain other gram-negative microorganisms will be described.

Phagocytosis and killing of gram-positive Bacillus megaterium and Micrococcus lysodeikticus by granulocytes in vitro is associated with almost immediate cessation of bacterial protein synthesis. By contrast, protein synthesis by Escherichia coli continues after ingestion and killing. After preincubation of E. coli with intact granulocytes for 15 min, when 95% or more of the bacteria can no longer multiply, induction of 6-galactosidase proceeds at rates about half of control values. With disrupted granulocytes, which kill E. coli as rapidly as intact cells, the rate of induction of ,B-galactosidase does not fall until after 30 min of preincubation. We attribute the different effects of phagocytosis on the biochemical apparatus of these microorganisms to the different fates of their envelopes. Specifically labeled protein, ribonucleic acid, deoxyribonucleic acid, and lipid of all three species of bacteria and peptidoglycan of E. coli are apparently incompletely degraded during phagocytosis. However, the cell walls of M. lysodeikticus and B. megaterium undergo rapid and almost complete degradation. The resulting structural disintegration of these gram-positive microorganisms must cause extensive biochemical disorganization as well. Our evidence indicates that the E. coli envelope, on the other hand, retains sufficient structural organization to preserve integrated biochemical function for at least 1 h after the bacteria have lost the ability to multiply. on August 8, 2020 by guest http://jb.asm.org/ Downloaded from the synthesis of'-galactosidase by Escherichia coli. J. Mol. Biol. 1:165-178. 13. Patriarca. P., S. Beckerdite, and P. Elsbach. 1972. Phospholipases and phospholipid turnover in Escherichia coli spheroplasts. Biochim. Biophys. Acta 260:59:3-60(0.

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