Effects of levorphanol on phospholipid metabolism and composition in Escherichia coli

Alkaloids, Nitric Oxide, and Nitrite Reductases: Evolutionary Coupling as Key Regulators of Cellular Bioenergetics with Special Relevance to the Human Microbiome

Typical alkaloids expressed by prokaryotic and eukaryotic cells are small heterocyclic compounds containing weakly basic nitrogen groups that are critically important for mediating essential biological activities. The prototype opiate alkaloid morphine represents a low molecular mass heterocyclic compound that has been evolutionarily fashioned from a relatively restricted role as a secreted antimicrobial phytoalexin into a broad spectrum regulatory molecule. As an essential corollary, positive evolutionary pressure has driven the development of a cognate 6-transmembrane helical (TMH) domain μ3 opiate receptor that is exclusively responsive to morphine and related opiate alkaloids. A key aspect of “morphinergic” signaling mediated by μ3 opiate receptor activation is its functional coupling with regulatory pathways utilizing constitutive nitric oxide (NO) as a signaling molecule. Importantly, tonic and phasic intra-mitochondrial NO production exerts profound inhibitory effects on the rate of electron transport, H+ pumping, and O2 consumption. Given the pluripotent role of NO as a selective, temporally-defined chemical regulator of mitochondrial respiration and cellular bioenergetics, the expansion of prokaryotic denitrification systems into mitochondrial NO/nitrite cycling complexes represents a series of evolutionary modifications of existential proportions. Presently, our short review provides selective discussion of evolutionary development of morphine, opiate alkaloids, μ3 opiate receptors, and NO systems, within the perspectives of enhanced mitochondrial function, cellular bioenergetics, and the human microbiome.

Microbiome: A Potential Component in the Origin of Mental Disorders

It is not surprising to find microbiome abnormalities present in psychiatric disorders such as depressive disorders, bipolar disorders, etc. Evolutionary pressure may provide an existential advantage to the host eukaryotic cells in that it survives in an extracellular environment containing non-self cells (e.g., bacteria). This phenomenon is both positive and negative, as with other intercellular processes. In this specific case, the phenomenal amount of information gained from combined bacterial genome could enhance communication between self and non-self cells. This can be coupled to both pathological processes and healthy ones. In this review, we chose to examine potential associated disorders that may be coupled to the microbiome, from the perspective of their bidirectional communication with eukaryotic cells in the gut. Cognition, being the newest neural networking functionality to evolve, consumes a good amount of organismic energy, 30% of which arises from the gut flora. Furthermore, the mammalian gut is highly innervated and has a highly developed immune component, reflecting brain complexity. The brain-gut axis uses similar molecular messengers as the brain, which affects bacterial processes as well. Thus, any modification of normal bacterial processes may manifest itself in altered behavior/cognition, originating from the gut. The origin of some disorders associated with this bidirectional communication may be harnessed to restore normal functioning.

Deficiency in sPLA(2) does not affect HDL levels or atherosclerosis in mice

Secretory non-pancreatic phospholipase A(2) (sPLA(2)) has been implicated in inflammation and has been found in human atherosclerotic lesions. To test the effect of sPLA(2) deficiency on atherosclerosis, C57BL/Ks mice (apoE(+/+) and PLA(2)(++) were bred with C57BL/6 apoE knockout mice which are sPLA(2)(--) due to a spontaneous mutation. Sibling pairs of mice (apoE(--)/sPLA(2)(++) and apoE(--)/sPLA(2)(--)) on high fat Western diets were dissected at 22 weeks. In vitro enzyme assays confirmed higher serum sPLA(2) activity in the sPLA(2)(++) compared to sPLA(2)(--) for both sexes, while sPLA(2)(--) males had slightly higher serum cholesterol and phospholipids. Analysis of lipoprotein profiles by FPLC showed no effect of sPLA(2) genotype on any measured parameters. Atherosclerosis was quantitated by assaying cholesterol in aortic extracts. Male sPLA(2) trended slightly higher than sPLA(2)(++) with no statistical significance. Female sPLA(2)(++) and sPLA(2)(--) mice showed no significant differences in any of the measured parameters. These results suggest that the endogenous mouse sPLA(2) gene does not significantly affect HDL or atherosclerosis in mice.

Exocellular phospholipase C activity from a Propionibacterium acnes strain isolated from a periodontal pocket

The culture supernatant of a strain of Propionibacterium acnes was investigated for its phospholipase (PL) activity. The microorganism was isolated from a periodontal pocket of a patient with periodontal disease. Supernatants from cultures of this microorganism were used as a source to obtain enzymes. Proteins from the supernatants were concentrated, and their enzymatic activity was partially purified through molecular sieving. The procedure yielded two peaks of activity. This activity was shown to hydrolyze phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) and was effective in a pH range of 5 to 9, with an optimal activity at pH 7.0. Divalent cations were not required for activity of the enzymes. Analysis of the products obtained from the hydrolysis of PC labeled in the choline, phosphoryl, or acyl moieties and PE containing labeled oleic acid indicated that the supernatants' activity was mostly phospholipase C (PL-C). Phospholipase C can act synergistically with other factors to produce tissue damage, and hence may contribute to the pathogenesis of periodontal disease.

Vasoactive intestinal peptide and helodermin inhibit phospholipase A2 activity in vitro

We recently reported that the widely distributed neuropeptide vasoactive intestinal peptide (VIP) reduces inflammatory lung injury due to a variety of agents and inhibits the associated generation of cyclo-oxygenase and lipoxygenase products. We therefore investigated whether VIP may inhibit phospholipase A2 activity, thus reducing the release of arachidonic acid, the common precursor of all eicosanoids. VIP dose-dependently inhibited PLA2 of porcine pancreas and of Naja naja venom, as assessed by the release of free [3H]oleic acid from labeled Escherichia coli phospholipids. The potency of VIP was similar to that of mepacrine, with 50% inhibition at 400-500 microM. The closely related peptide helodermin produced 50% inhibition at 200 microM, but secretin and peptide histidine isoleucineamide produced little or no inhibition. The results suggest that VIP and helodermin selectively inhibit PLA2 in vitro. If this activity is exerted in vivo, it may contribute to the anti-inflammatory activity of these two peptides.

Plasma phospholipase A2 activity in clinical acute myocardial infarction

1. Phospholipase A2 (PLA2) cleaves phospholipids to produce a lyso-phospholipid and free fatty acid and, in view of the biological activity of the products, PLA2 may play a role in many disease states. Lyso-phospholipids and free arachidonic acid increase in ischaemic myocardium, indicating that ischaemia activates the enzyme. 2. Plasma PLA2 activity was measured in patients with acute myocardial infarction, based on the release of labelled arachidonic acid from Escherichia coli cell membrane. Fourteen males (peak serum creatine phosphokinase (CK) above twice upper normal) were studied on day 1 (within 6 h of chest pain onset), days 2-4, and days 6-9. Normal age matched males (n = 13) were also studied. 3. Plasma PLA2 in patients with uncomplicated myocardial infarction (n = 12) was, initially, 1.14 +/- 0.10 (s.e.m.) nmol/min per mL plasma, similar to that in the normal group (1.52 +/- 0.14). On days 2-4, PLA2 activity increased to 1.94 +/- 0.18 (P less than 0.001) and this activity was correlated with the earlier peak CK level (P less than 0.02). On days 6-9, PLA2 activity was 1.49 +/- 0.13 while in two patients who developed complications and underwent open-heart surgery between the last two measurements, there were further increases to 4.22 and 4.04 nmol/min per mL. 4. The increase in plasma PLA2 in uncomplicated myocardial infarction is likely to be due to release from the damaged myocardium; whether it contributes to pathophysiology is uncertain.

The metabolism of CDP-diacylglycerol and phosphatidylinositol in the microsomal fraction of rat liver. Effects of chlorpromazine, magnesium and manganese

1. The metabolism of CDPdiacylglycerol and phosphatidylinositol was measured using substrates bound to the microsomal membranes of rat liver. 2. Chlorpromazine inhibited the degradation of [14C]CDPdiacylglycerol and the concomitant inositol-independent release of 14C in water-soluble products in the presence of various concentrations of Mg2+ and Mn2+. 3. The activity of CDPdiacylglycerol inositol phosphatidyltransferase was measured by determining the rate of incorporation of [3H]inositol into phosphatidylinositol, and by the inositol-dependent release of water-soluble 14C from [14C]CDPdiacylglycerol. Both of these parameters were inhibited by chlorpromazine in incubations that contained rate-limiting concentrations of Mg2+. However, chlorpromazine stimulated the reaction when 20 mM Mg2+, 0.5 mM Mn2+, 2 mM Mn2+ or 20 mM Mn2+ was added to the incubations. 4. Low concentrations of chlorpromazine increased an inositol-exchange reaction in the presence of 0.5 mM Mn2+ whereas higher concentrations of chlorpromazine inhibited. Chlorpromazine had relatively less effect on the inositol-exchange reaction at higher concentrations of Mn2+. 5. The action of chlorpromazine in decreasing the breakdown of CDPdiacylglycerol and in stimulating its conversion to phosphatidylinositol could explain part of the mechanism by which this compound and other amphiphilic cations increase the synthesis of acidic phospholipids.

Effect of chronic administration of morphine on primary immune response in mice

The effect of 3 different doses of chronically-administered morphine on the primary immune response was studied in mice by estimating spleen/body weight ratio and serum hemolysin production against sheep red blood cells (SRBC). It was observed that morphine exerted a dose-dependent inhibitory effect on the immune response which was antagonized by the concomitant administration of naloxone. The findings suggest that the inhibitory effect of morphine is specific.

Lipid and lipopolysaccharide composition of Escherichia coli surface-altered mutants selected for resistance to levallorphan, tetracaine, and polymyxin

Certain mutants of Escherichia coli with an altered permeability barrier have an essentially normal lipopolysaccharide, fatty acid, and phospholipid content, with a slight increase in the membrane protein:lipid ratio. The phospholipid metabolism of the lev and tec strains shows an abnormal response to growth in the selective agents levallorphan and tetracaine, respectively.

The effects of amphiphilic compounds on phosphatidate metabolism

Amphiphilic cations interact with phosphatidate and thereby change its physical properties. This interaction can redirect phospholipid metabolism. In the presence of Mg2+ amphiphilic cations inhibit the activity of phosphatidate phosphohydrolase and stimulate that of phosphatidate cytidylyltransferase. Increasing the concentration of Mg2+ further, or adding Ca2+ have similar effects, except that Ca2+ does not stimulate phosphatidate cytidylyltransferase activity. Amphiphilic anions reverse the effects caused by the amphiphilic cations. The implication of these results are discussed in relation to the pharmacological effects of amphiphilic cationic drugs.

The prerequisites for local lysolecithin formation in the human gallbladder. II. Studies on the positional specificity of the phospholipase A activity

The positional specificity of the phospholipase A in human gallbladder epithelium was studied by using biosynthetically radioabeled diacylphosphoglycerides as substrates. Diacylphosphoglyceride in 14C-palmitic acid-labeled, autoclaved E.coli was hydrolyzed under the formation of monoacylphosphoglyceride and fatty acid that were both radiolabled. In contrast, diacylphosphoglyceride in 14C-oleate-labeled bacteria was hydrolyzed so as to give radiolabel in the fatty acid only. Since 14C-palmitate occupies predominantly the 1-acyl position and 14C oleate the 2-acyl position of the major E. coli diacylphosphoglycerides, these findings suggest that: 1) the phospholipase attacks and 2-position of diacylphosphoglycerides, and 2) a complete deacylation of diacylphosphoglycerides in the gallbladder wall is brought about by the combined action of phospholipase A2 and lysophospholipase, the latter being able to hydrolyze the 1-acyllysophosphoglyceride. It appears, therefore, that the biochemical preequisites for a local formation and degreadation of lysolecithin in the gallbladder itself are met by the positional specificity of theenzymes present. This finding further substantiates the hypothesis that lysolecithin is an adjustable mediator of aseptic cholecystitis.

The use of a phospholipase A-less Escherichia coli mutant to establish the action of granulocyte phospholipase A on bacterial phospholipids during killing by a highly purified granulocyte fraction

Phospholipase A2 present in a highly purified, potently bactericidal, fraction from rabbit graulocytes produces net bacterial phospholipid degradation during killing of a phospholipase A-less strain of Escherichia coli. In the wild-type parent strain phospholipid breakdown is caused not only by the action of phospholipase A2 but also by phospholipase A1, indicating activation of the most prominent phospholipase of E. coli. This activation occurs as soon as the bacteria are exposed to the granulocyte fraction. Phospholipid breakdown by both phospholipases A is dose dependent but reaches a plateau after 30-60 min and at higher concentrations of the fraction. Phospholipid degradation is accompanied in both strains by an increase in permeability to actinomycin D that is also dose dependent. Even though net hydrolysis of phospholipids is greater in the parent strain than in the mutant, the increase in permeability is the same in the two strains. The addition of 0.04 M Mg2+, after the effects on phospholipids and permeability have become manifest, initiates in both strains the restoration of insensitivity to actinomycin D, the net resynthesis of phospholipids, and the disappearance of monoacylphosphatides and the partial disappearance of free fatty acids that had accumulated. Loss of ability to multiply is not reversed by Mg2+ in either strain. Less than 5 micrograms of granulocyte fraction causes loss of viability of from 90 to 99% of 1 X 10(8) microorganisms of both strains. However, at lower concentrations the parent strain is considerably more sensitive to the bactericidal effect of the granulocyte fraction than the mutant strain.

Relationship between phospholipid compositions and transport activities of amino acids in Escherichia coli membrane vesicles

Cells of Escherichia coli were incubated in broth medium in the presence of 5 mM of hydroxylamine which completely inhibited growth but did not affect viabilities. Hydroxylamine is known to inhibit phosphatidylserine decarboxylase. A large amount of phosphatidylserine (up to 20% of total phospholipids), which did not occur in normal cells, accumulated accompanied with a decrease in phosphatidylethanolamine. Higher uptake activities of serine and glutamate were observed with the hydroxylamine-treated cells than control cells. When membrane vesicles from hydroxylamine-treated cells were prepared, they also displayed higher uptake activities of serine, proline, glutamate, and threonine than those of normal membranes. When hydroxylamine-treated cells were incubated with chloramphenicol, at concentrations which almost completely inhibited protein synthesis, the composition of phosphatidylserine decreased with a concomitant increase in that of phosphatidylethanolamine. The phospholipid composition of these cells incubated for 5 h with chloramphenicol became almost normal. Membranes vesicles prepared from such cells displayed reduced uptake activities, which were close to those of normal vesicles. These results were interpreted as indicating the altered transport activities due to the altered phospholipid composition.

Use of polymyxin B, levallorphan, and tetracaine to isolate novel envelope mutants of Escherichia coli

Mutants of Escherichia coli were isolated by their resistance to the bacteriocidal effects of the membrane-active drugs polymyxin B, levallorphan, and tetracaine. The mutants were examined for additional changes in cellular physiology evoked by the lesions; many polymyxin-resistant strains had a concomitant increased sensitivity to anionic detergents, and several strains of each type had concomitant alterations in generation time and morphology. Mutants of each class (polymyxin resistant, tetracaine resistant, and levallorphan resistant) were transduced into recipient strains. The levallorphan resistance site (lev) was located at approximately 9 min on the E. coli chromosome. Polymyxin (pmx) and tetracaine (tec) resistance loci were also transduced. The lev and tec strains had a slight prolongation of generation time, in contrast with their isogenic wild-type strains. The tec transductant produced long filaments in the absence of tetracaine and had an altered colonial morphology, it reverted at high frequency, with the morphological abnormalities reverting along with the tetracaine resistance. The pmx transductant had an increased sensitivity to levallorphan and to anionic detergents. In contrast, both lev and tec mutants were more resistant to acriflavine than was the wild type or the pmx transductant. The pmx, lev, and tec loci differed in sensitivity to mitomycin C; the lev strain was more resistant, the tec strain was more sensitive, and the pmx strain was much more sensitive than the wild type. There was no difference in sensitivity to several other dyes and detergents, colicins, or T bacteriophage between the transductant and isogenic wild-type strains. Thus, lev, tec, and pmx loci confer more subtle alterations in the permeability barrier than do lipopolysaccharide-deficient mutants previously studied.

Altered phospholipid metabolism in Escherichia coli accompanying killing by disrupted granulocytes

The effect of bactericidal concentrations of disrupted rabbit granulocytes and of partially purified granulocyte fractions on phospholipid metabolism by Escherichia coli has been investigated. Previous studies in this laboratory have shown that, during and after killing of E. coli by granulocytes, bacterial macromolecular synthesis continues. Similarly, despite almost complete loss of viability within 15 min, incorporation of [1-(14)C]palmitate, [2-(14)C]glycerol, and [1-(14)C]acetate into E. coli phospholipids, in the presence of granulocyte preparations, remains the same as in control E. coli populations for at least 1 h. Incorporation of [1-(14)C]oleate into E. coli phospholipids is actually stimulated during the first 60 min of incubation in the presence of granulocyte preparations (more than twofold at 30 min and 40% at 60 min). With all labeled lipid precursors, bactericidal granulocyte preparations cause a relative increase in the labeling of E. coli cardiolipin, with a corresponding drop in labeled phosphatidyl-glycerol. Labeled lyso-compounds accumulate in the presence of granulocyte preparations when [1-(14)C]palmitate, but not when [1-(14)C]oleate is the labeled precursor. Since oleate occurs mainly in the 2-acyl position of E. coli phospholipids, whereas at least 50% of palmitate occurs in the 1 position, it appears that a phospholipase A(2) acts on the E. coli phospholipids. These various effects are also seen when E. coli are exposed to highly purified granulocyte preparations that possess potent bactericidal and phospholipase A(2) activities. We speculate that this phospholipase A(2) in the granulocyte preparations stimulates oleate but not palmitate incorporation by initiating increased turnover of the fatty acid in the 2-acyl position of E. coli phospholipids, causing formation of 1-acyl lyso-compounds likely to be preferentially reacylated with unsaturated fatty acids.

Inhibition by levorphanol and related drugs of amino acid transport by isolated membrane vesicles from Escherichia coli

Levorphanol inhibits the transport of the amino acids proline and lysine by cytoplasmic membrane vesicles derived from Escherichia coli. The degree of inhibition increases with increasing levorphanol concentration and ranges from 26% at 10(-6) M levorphanol to 92% at 10(-3) M levorphanol. The effect is independent of the energy source, since levorphanol inhibits proline uptake to the same extent in the presence of 20 mM d-lactate or 20 mM succinate and in the absence of an exogenous energy source. Levorphanol does not irreversibly alter the ability of membrane vesicles to transport proline, since incubation of membrane vesicles for 15 min in the presence of 0.25 mM levorphanol, a concentration which inhibits proline transport by more than 75%, has no effect on the rate of proline transport by these vesicles once the drug is removed. Both the maximum velocity and the K(m) of proline transport are modified by levorphanol, hence, the type of inhibition produced by levorphanol is mixed. The inhibitor constant (K(i)) for levorphanol inhibition of proline transport is approximately 3 x 10(-4) M. Membrane vesicles incubated in the presence of levorphanol accumulate much less proline at the steady state than do control vesicles. Furthermore, the addition of levorphanol to membrane vesicles preloaded to the steady state with proline produces a marked net efflux of proline. Levorphanol does not block either temperature-induced efflux or exchange of external proline with [(14)C]proline present in the intravesicular pool. Dextrorphan, the enantiomorph of levorphanol, and levallorphan, the N-allyl analogue of levorphanol, inhibit proline and lysine transport in a similar manner. Possible mechanisms of the effects of these drugs on cell membranes are discussed.

Effects of human and rabbit serum on viability, permeability, and envelope lipids of Serratia marcescens

The major action of serum on gram-negative organisms is thought to be on the microbial envelope. We compared the effects of normal human and rabbit serum on the envelope lipids of two strains of Serratia marcescens, one sensitive and one resistant to the bactericidal effects of serum. During killing by either serum, the sensitive strain underwent rapid permeability changes coincident with degradation of microbial phospholipids. The resistant strain exhibited none of these effects. The phospholipid degradation that accompanies killing of the sensitive strain by serum could be caused by phospholipases present in serum or by Serratia's own phospholipid-splitting enzymes. The results indicate that phospholipid breakdown is caused by activation of bacterial of bacterial phospholipases and not by serum phospholipases. This conclusion is based upon the following findings.(i1 Although rabbit serum phospholipase A was at least 10 times more active than human serum phospholipase A, phospholipid degradation in the sensitive Serratia strain was comparable during (equally rapid) killing by human or rabbit serum. (ii) Heat treatment (56 C) of both sera eliminated bactericidal activity as well as microbial lipid degradation but abolished phospholipase activity of human serum only. (iii) Virtually complete removal of phospholipase A activity from human serum by adsorption onto autoclaved Micrococcus lysodeikticus had no effect on the extent of phospholipid hydrolysis or on bactericidal activity. Activation by serum of endogenous phospholipase activity in S. marcescens was accompanied by enhanced incorporation of lipid precursors into bacterial lipids. No evidence was found for increased turnover of protein or ribonucleic acid during killing by serum.

Early and discrete changes in permeability of Escherichia coli and certain other gram-negative bacteria during killing by granulocytes

Rapid killing of Escherichia coli by intact or disrupted rabbit granulocytes or by granulocyte fractions was found to be accompanied by an equally rapid increase in permeability of the E.coli envelope. This increase in permeability was detected by determining entry of substances that normally do not cross E.coli's permeability barrier, namely actinomycin D and o-nitrophenyl-beta-D-galactopyranoside (ONPG), a substrate for cytoplasmic beta-galactosidase. Because E.coli continue to incorporate radioactively labeled precursors into bacterial RNA and protein for at least 1 h, despite rapid killing by granulocytes, entry of actinomycin D could be measured by its inhibitory effect on macromolecular synthesis. Entry was evident within minutes after exposure to granulocytes or granulocyte fractions and is independent of pH over a range of 6.5-9.0. The effect of disrupted granulocytes or partially purified fractions on susceptibility of E.coli to actinomycin D and entry of ONPG is dose dependent. That the entry of actinomycin D and ONPG was not caused by gross destruction of the envelope is indicated by two sets of observations: (a) net influx of (42)K was maintained for at least 15 min, even though efflux of potassium was immediately accelerated upon addition of bactericidal concentrations of granulocyte fractions; (b) beta-galactosidase did not leak out of E.coli under conditions that produce maximal inhibition by actinomycin D. Different species of gram-negative bacteria exhibited different susceptibilities to the bactericidal and permeability effects of granulocyte fractions. Thus, three strains of E.coli and one strain of Salmonella typhimurium were highly susceptible to both the bactericidal and the permeability enhancing effects of granulocyte fractions, whereas two strains of Serratia marcescens and one strain of Pseudomonas aeruginosa were resistant to both effects. Another strain of P. aeruginosa was rendered susceptible to actinomycin D without being killed and two strains of S. typhimurium remained insensitive to actinomycin D while being killed by granulocytes.

Persistence of regulation of macromolecular synthesis by Escherichia coli during killing by disrupted rabbit granulocytes

Escherichia coli incubated in balanced salt solution with glucose as a carbon source but no nitrogen source exhibit a marked step-up of macromolecular synthesis when various non-bactericidal tissue extracts, or fractions thereof, are added. When disrupted granulocytes that cause rapid loss of viability are added, a step-up is also observed; i.e., incorporation of labeled precursors into ribonucleic acid is stimulated more than 15-fold, and incorporation into protein and deoxyribonucleic acid about twofold. This stimulation of macromolecular synthesis is still evident 30 min after more than 95% of the E. coli have lost their ability to multiply. Stimulation by disrupted granulocytes of [(14)C]leucine incorporation into E. coli protein occurs over a wide range of leucine concentrations but is usually eliminated by adding a Casamino Acids mixture or another more complete medium. The substance(s) in tissue homogenates that trigger step-up is heat stable and dialyzable. Thus, E. coli exposed to the bactericidal and digestive components of disrupted granulocytes and no longer capable of division maintain their ability to regulate macromolecular synthesis in response to changes in nutritional conditions for at least 1 h.

Effects of phagocytosis by rabbit granulocytes on macromolecular synthesis and degradation in different species of bacteria

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 beta-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 beta-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.