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Novel peptidoglycans in Caulobacter and Asticcacaulis spp.

Peptidoglycan sacculi free of poly-beta-hydroxybutyric acid were prepared from whole cells of four species of Caulobacter and two species of Asticcacaluis and from morphological mutants of Caulobacter crescentus and Caulobacter leidyi. Acid hydrolysates of the sacculi were analyzed quantitatively, and each of the hydrolysates was found to contain significant amounts of only five ninhydrin-reactive compounds: alanine, glutamic acid, alpha , omega-diaminopimelic acid, muramic acid, and glucosamine. Four types of peptidoglycans were distinguishable on the basis of the molar ratios among these five compounds. The respective ratios were as follows: in C. leidyi, 2:1:1:1:0.8; in Asticcacaulis biprosthecum, 1.7:1.6:1.1:0.7; in the cells of the remaining species, 2:1:1:1.2:0.8; and in stalks shed by the abscission mutant 2NY66, 2:1:1:1:1.67. Thus, in addition to some species differences among these caulobacters, it was found that the peptidoglycan sacculus of the stalked C. crescentus cell is chemically differentiated; the cellular peptidoglycan is richer in muramic acid than is the peptidoglycan of typical gram-negative bacteria, and the peptidoglycan of the stalk is correspondingly rich in glucosamine. Empirical formulas for the repeating units of the peptidoglycans have been inferred on the basis of the molar ratios of their amino components.

Alanine↗

Quantitative chemical composition of peptidoglycan of Listeria monocytogenes.

The qualitative and quantitative chemical composition of the peptidoglycan layer of Listeria monocytogenes cell walls was determined. The peptidoglycan layer was isolated from intact cells after treatment with sodium lauryl sulfate and digestion with Pronase. The isolated peptidoglycan contained carbohydrates which included hexose, rhamnose, and amino sugars. The amino sugar was identified as glucosamine which was present in very high micromole concentration, as compared with the amino acids, muramic acid, or diaminopimelic acid. In addition, protein and phosphorus were also present. However, the presence of teichoic acid was not detected in the peptidoglycan. Protein moiety contained a total of 18 amino acids with lysine as the N-terminal amino acid.

Amino Acids↗

Use of gas chromatography-ion trap tandem mass spectrometry for the detection and characterization of microorganisms in complex samples.

Gas chromatography-mass spectrometry (GC-MS) can be applied to detect and characterize microorganisms in clinical and environmental samples, and microbial contaminants in biotechnological production cultures. With this approach, unique microbial monomeric compounds, known as chemical markers, are used as analytes. In the present article, two GC-MS-based techniques, viz. GC-ion trap tandem MS (GC-MS-MS) and conventional quadrupole GC-MS used in the selected ion monitoring mode, were compared regarding their ability to detect 3-hydroxy fatty acids, muramic acid, and ergosterol (markers for endotoxin, peptidoglycan, and fungal biomass, respectively) in complex matrices. When using GC-MS-MS, daughter ion spectra were obtained for all markers present in amounts close to the detection limit of the GC-MS. Ion-trap GC-MS-MS shows great promise as a chemical marker analysis technique for application in clinical diagnosis, occupational and public health care, and biotechnology.

Bacteria↗

Surface layers of Xanthomonas malvacearum, the cause of bacterial blight of cotton.

Mureins were isolated from two strains of Xanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70-95 % and the amino acid and amino sugar components (glutamic acid, alanina, meso-disminopimelic acid, muramic acid and glucosamine) were present at the molar ratio of 1:1.9:1:l.12.0.85. The bacterium secreted a copious amount of slime which masked itd surface structure. The slime was composed of densley interwoven network of filamentous material originating from the cell surface and extended into the medium without and discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formatin of baterial cells.

Amino Acids↗

The effect of cell wall components on glycine-enhanced sterol side chain degradation to androstene derivatives by mycobacteria.

beta-Sitosterol side chain degradation by Mycobacterium sp. NRRL MB 3683 results in the formation of androstene derivatives and is increased in the presence of glycine. As the sterol transformation is carried out inside the cell, higher product accumulation could indicate faster diffusion of highly hydrophobic substrate through the cell wall permeability barrier. Cell wall preparations were obtained to analyse the effect of glycine on peptidoglycan components. Peptidoglycan is known to be the target for glycine action. In glycine-treated preparations, the molar ratio of diaminopimelic acid:muramic acid, the marker compounds of tetrapeptides and glycan strands respectively, was about 60% lower than in the control. This indicates a possible reduction in cross-linking between peptide units and the destruction of peptidoglycan. Unexpectedly, glycine also caused changes in the relative proportion of mycolic acids to other lipids occurring in the strain used for this study. The enhancement of beta-sitosterol side chain degradation is likely to result from disturbing the integrity of the cell wall components responsible for the permeability barrier in mycobacteria.

Androstenes↗

Chemical characterization of the isolated cell surface of Amoeba.

The cell surface has been isolated from uninucleate, freshwater, phagocytic amoebae by a new procedure. Several criteria were employed to demonstrate purity of the cell surface fraction. All morphological components of the tripartite surface were present in the isolated surface and the weight of the isolated surface was quantitatively accounted for by the components analyzed. Chemical analyses showed the presence of lipid, protein, and carbohydrate. Mannose was the predominant neutral sugar. Analyses for three different strains of Amoeba were similar. Phosphate was found to be the major anionic group in the cell surface material. Sulfate, uronic acid, sialic acid, muramic acid, and nonamidated glutamic acid and aspartic acid were absent. Evidence is presented suggesting that the phosphate is associated with an unidentified nonreducing polyol.

Acid Phosphatase↗

Folate derived from cecal bacterial fermentation does not increase liver folate stores in 28-d folate-depleted male Sprague-Dawley rats.

This study assessed the ability of rats to absorb and store the folate synthesized by cecal bacteria. Male weanling Sprague-Dawley rats were folate depleted by feeding a low folacin AIN93G formulated basal diet for 28 d; they were then fed repletion diets containing folate (0.25-1.0 mg/kg diet), dietary fiber (DF; wheat bran, oat bran, ground corn, wheat germ) or undigested and fermented dietary material (UFDM; polydextrose, inulin) in the presence and absence of an antibiotic (succinylsulfathiazole). Fermentation was stimulated by DF and UFDM and reduced by the antibiotic. In the absence of succinylsulfathiazole, the increase in liver folate (during the repletion phase) was proportional only to the folate content of the diet and did not vary with added DF or UFDM. Adding succinylsulfathiazole lowered total folate excretion from 13.8 +/- 8.2 to 4.8 +/- 2.9 nmol/d (pooled diets, P < 0.00001) in agreement with its role in inhibiting bacterial folate synthesis. In addition, succinylsulfathiazole lowered liver folate in rats fed control and test diets approximately equally with a mean decrease from 11.6 +/- 2.5 to 7.5 +/- 2.5 nmol/g wet liver (pooled diets, P < 0.00001), suggesting that the antibiotic also affected rat folate absorption and/or metabolism. Increased bacterial fermentation and excretion as well as increased bacterial folate production in the presence of added DF and UFDM were demonstrated by increased volatile fatty acid content in cecal and fecal samples (P < 0.000001) and increased diaminopimelic acid, muramic acid and folate in feces (P < 0.00001). The magnitude of these changes depended on the type of DF and UFDM. These results show that bacterially synthesized folate is not substantially absorbed and stored in the liver of Sprague-Dawley male rats.

Animals↗

Isolation of group H streptococcal competence factor.

Competence factor (CF) was purified 600-fold from culture filtrates of competent group H streptococcus, strain Challis, by fractionation on a carboxymethyl-Sephadex column. The preparation did not contain orcinol- or diphenylamine-positive material, and CF activity was destroyed by trypsin. An examination of its chemical composition revealed 10 amino acids, muramic acid, glucosamine, and glucose.

Amino Acids↗

Adjuvant activity of purified peptidoglycan of Listeria monocytogenes in mice and guinea pigs.

The immunological properties of peptidoglycan (L-PG) purified from the cell wall skeleton (L-CWS) of Listeria monocytogenes strain EGD were investigated and compared with the properties of L-CWS. L-PG consisted of alanine, glutamic acid, alpha, epsilon-diaminopimelic acid, muramic acid, and glucosamine. L-PG showed potent adjuvant activities for circulating antibody formation and development of delayed-type hypersensitivity to bacterial alpha-amylase in vivo and for the primary immune response to sheep erythrocytes in vitro, as well as L-CWS. Both L-PG and L-CWS enhanced the generation of cell-mediated cytotoxicity in allogeneic mice and activated thioglycolate-elicited peritoneal macrophages and macrophage cell line RAW 264 to kill tumor target cells in vitro. We also found that L-PG acted on normal spleen cells as a mitogen. Both L-PG and L-CWS had tumor (Meth A)-suppressive and -regressive activities in syngeneic mice. Our results suggest that the L-PG moiety retains the adjuvant and antitumor activities of L-CWS.

Adjuvants, Immunologic↗

Penicillin-induced formation of osmotically stable spheroplasts in nongrowing Bdellovibrio bacteriovorus.

Bdellovibrio peptidoglycan is of typical gram-negative composition. The molar ratios of alanine:glutamic acid:diaminopimelic acid:muramic acid:glucosamine were about 2:1:1:1:1. Nascent, nongrowing Bdellovibrio bacteriovorus 109J were converted from highly motile vibrios to highly motile spheres when shaken in dilute buffer plus penicillin, cephalothin, bacitracin, or D-cycloserine. The spherical forms contained essentially no sedimentable peptidoglycan; i.e., they were spheroplasts. Spheroplasts induced by penicillin, D-cycloserine, and lysozyme were stable in dilute buffer and did not lyse when subjected to osmotic shock. Normal Bdellovibrio suspended in buffer turned over their peptidoglycan at a rate of approximately 30% h during the initial 120 min of starvation. Chloramphenicol and sodium azide strongly inhibited Bdellovibrio peptidoglycan turnover and the induction of spheroplasts by penicillin. The data indicate that nongrowing B. bacteriovorus are sensitive to penicillin and other antibiotics affecting cell walls because of their high rate of peptidoglycan turnover. It is also concluded that an intact peptidoglycan layer is required for maintaining cell shape, but is not required for osmotic stability of B. bacteriovorus.

Bacterial Proteins↗

Peptidoglycan-polysaccharide complex in the cell wall of the filamentous prochlorophyte Prochlorothrix hollandica.

A peptidoglycan-polysaccharide complex composed of N-acetylglucosamine, N-acetylmuramic acid, muramic acid 6-phosphate, L-alanine, D-alanine, D-glutamic acid, meso-diaminopimelic acid, N-acetylmannosamine, mannose, galactose, glucose, and phosphate was isolated from cell walls of the filamentous prochlorophyte Prochlorothrix hollandica; this complex was similar in chemical composition and structure to that found in cyanobacteria. Peptide patterns of partial acid hydrolysates of the isolated peptidoglycan revealed an A1 gamma structure with direct cross-linkage (m-diaminopimelic acid-D-alanine) of the peptide side chains. The degree of cross-linkage (63%) was found to be in the range of values obtained for gram-positive bacteria and cyanobacteria.

Amino Acids↗

Peptidoglycan-associated polypeptides of Mycobacterium tuberculosis.

Important protein-based immunoreactivities have long been associated with the cell wall core of mycobacteria. In order to explore the molecular basis of such activities, purified cell walls of Mycobacterium tuberculosis were extracted with sodium dodecyl sulfate to produce an insoluble residue composed of the mycolylarabinogalactan-peptidoglycan complex and about 2% of unextractable protein. Treatment of the product from an avirulent strain of M. tuberculosis with trifluoromethanesulfonic acid released a single polypeptide with a molecular size of 23 kilodaltons, accounting for all of the insoluble cell wall protein. Extensive purification and then analysis of the 23-kilodalton protein demonstrated the absence of diaminopimelic acid, muramic acid, or other peptidoglycan components, pointing to either a novel linkage between protein and peptidoglycan or a noncovalent but tenacious association. The released 23-kilodalton protein showed amino acid homology and other similarities to the outer membrane protein OmpF of Escherichia coli. Although a similar product was released in small quantities from cell walls of the virulent M. tuberculosis Erdman and H37Rv by lysozyme treatment, the cell walls of virulent bacilli were dominated by the presence of poly-alpha-L-glutamine, accounting for as much as 10% of their weight. The poly-alpha-L-glutamine was successfully separated from the cell wall proper, demonstrating again the absence of a covalent association between peptidoglycan and the polymer. The antigenicity of these products is demonstrated, and their roles vis-a-vis analogous polypeptides from other bacteria in immunogenicity, pathogenicity, and bacterial physiology are discussed.

Amino Acids↗

Microorganisms and volatile organic compounds in airborne dust from damp residences.

Airborne dust samples from damp (n = 9) and control (n = 9) residences were analyzed for microorganisms (molds and bacteria), bacterial markers (3-hydroxy fatty acids and muramic acid), and adsorbed volatile organic compounds (VOCs). The number of mold species was greater in the damp residences than in the controls (23 vs.18) and nine mold species were found only in damp residences. The levels of 3-hydroxy fatty acids and muramic acid correlated better in damp residences than in controls, indicating that damp conditions affect the bacterial flora of airborne dust. Identifications made by culture and microscopy of the major molds found, i.e. Aspergillus, Cladosporium, and Penicillum, coincided with the identification of VOCs known to be produced by these species. A number of additional VOCs irritating to the skin, eyes, or respiratory tract were also found. The results from this pilot study illustrate the diversity of microorganisms and VOCs present in the indoor environment and suggest that analysis of airborne dust may help to assess human exposure to microorganisms and chemical compounds.

Air Pollution, Indoor↗

Inhalation of swine dust induces cytokine release in the upper and lower airways.

In healthy subjects, acute inhalation of swine dust causes an influx of inflammatory cells into the airways and increased bronchial responsiveness. The exposure may also cause fever and generalized symptoms. It seems likely that proinflammatory cytokines are involved in the response to inhaled swine dust. Nasal and bronchoalveolar lavage (BAL) were performed before, and 7 and 24 h after the start of 3 h exposure to swine dust, during a period of work in a swine confinement building, in 22 healthy subjects. Lavage fluids were analysed with regard to the cellular response and concentrations of interleukin (IL)-1 alpha, IL-1 beta, IL-6 and tumour necrosis factor-alpha (TNF-alpha). Each subject carried personal samplers for exposure measurements. Inhalable dust and airborne endotoxin, 3-hydroxylated (2-OH) fatty acid and muramic acid were measured. Bronchial responsiveness to methacholine was investigated 1-2 weeks before and 7 h after the start of the exposure. Exposure caused fever (> 38 degrees C) in three subjects, and approximately 25% of the subjects experienced symptoms. Bronchial responsiveness to methacholine increased by 3.5 (1.6-4.8) doubling doses (median (25th-75th percentile)). Following exposure, granulocytes increased more than 50 fold in BAL fluid and more than 40 fold in nasal lavage fluid. IL-1 alpha and IL-1 beta increased significantly in BAL fluid (p < 0.05) and nasal lavage fluid (p < 0.01). IL-6 increased 25 fold in BAL and 15 fold in nasal lavage fluid (p < 0.001). TNF-alpha was below detection limit (0.25 ng.L-1) in most subjects before exposure and increased following exposure to 3.8 (2.4-5.7) and 1.3 (0.6-2.3) ng.L-1 in BAL and nasal lavage fluid, respectively, (p < 0.001). Total inhalable dust was 20.5 (14.6-30.0) mg.m-3 and the concentrations of airborne endotoxin, 3-OH fatty acid and muramic acid were 1.2 (0.8-1.4), 3.5 (2.2-4.5) and 0.9 (0.3-1.9) microgram.m-3, respectively. There was a significant correlation between the IL-6 response in BAL fluid and exposure to dust endotoxin activity and 3-OH fatty acids (p < 0.05). Otherwise, no significant correlations were found between exposure and the cytokine response. We conclude that exposure to swine dust causes an intense upper and lower airway inflammation, which involves the proinflammatory cytokines interleukin-1, interleukin-6 and tumour necrosis factor-alpha.

Adult↗

Cadaverine is covalently linked to peptidoglycan in Selenomonas ruminantium.

Cadaverine was found to exist as a component of cell wall peptidoglycan of Selenomonas ruminantium, a strictly anaerobic bacterium. [14C]cadaverine added to the growth medium was incorporated into the cells, and about 70% of the total radioactivity incorporated was found in the peptidoglycan fraction. When the [14C]cadaverine-labeled peptidoglycan preparation was acid hydrolyzed, all of the 14C counts were recovered as cadaverine. The [14C]cadaverine-labeled peptidoglycan preparation was digested with lysozyme into three small fragments which were radioactive and were positive in ninhydrin reaction. One major spot, a compound of the fragments, was composed of alanine, glutamic acid, diaminopimelic acid, cadaverine, muramic acid, and glucosamine. One of the two amino groups of cadaverine was covalently linked to the peptidoglycan, and the other was free. The chemical composition of the peptidoglycan preparation of this strain was determined to be as follows: L-alanine-D-alanine-D-glutamic acid-meso-diaminopimelic acid-cadaverine-muramic acid-glucosamine (1.0:1.0:1.0:1.0:1.1:0.9:1.0).

Alanine↗