The isolation of alpha epsilon-Diaminopimelic acid from Corynebacterium diphtheriae and Mycobacterium tuberculosis

The Gram-Positive Bacterial Cell Wall

The chapter about the Gram-positive bacterial cell wall gives a brief historical background on the discovery of Gram-positive cell walls and their constituents and microscopic methods applied for studying the Gram-positive cell envelope. Followed by the description of the different chemical building blocks of peptidoglycan and the biosynthesis of the peptidoglycan layers and high turnover of peptidoglycan during bacterial growth. Lipoteichoic acids and wall teichoic acids are highlighted as major components of the cell wall. Characterization of capsules and the formation of extracellular vesicles by Gram-positive bacteria close the section on cell envelopes which have a high impact on bacterial pathogenesis. In addition, the specialized complex and unusual cell wall of mycobacteria is introduced thereafter. Next a short back view is given on the development of electron microscopic examinations for studying bacterial cell walls. Different electron microscopic techniques and methods applied to examine bacterial cell envelopes are discussed in the view that most of the illustrated methods should be available in a well-equipped life sciences orientated electron microscopic laboratory. In addition, newly developed and mostly well-established cryo-methods like high-pressure freezing and freeze-substitution (HPF-FS) and cryo-sections of hydrated vitrified bacteria (CEMOVIS, Cryo-electron microscopy of vitreous sections) are described. At last, modern cryo-methods like cryo-electron tomography (CET) and cryo-FIB-SEM milling (focus ion beam-scanning electron microscopy) are introduced which are available only in specialized institutions, but at present represent the best available methods and techniques to study Gram-positive cell walls under close-to-nature conditions in great detail and at high resolution.

Enzymology of bacterial lysine biosynthesis

Bacteria have evolved three strategies for the synthesis of lysine from aspartate via formation of the intermediate diaminopimelate (DAP), a metabolite that is also involved in peptidoglycan formation. The objectives of this chapter are descriptions of mechanistic studies on the reactions catalyzed by dihydrodipicolinate synthase, dihydrodopicolinate reductase, tetrahydrodipicolinate N-succinyl-transferase, N-succinyl-L,L-DAP aminotransferase, N-succinyl-L,L-DAP desuccinylase, L,L-DAP epimerase, L,L-DAP decarboxylase, and DAP dehydrogenase. These enzymes are discussed in terms of kinetic, isotopic, and X-ray crystallographic data that allow one to infer the nature of interactions of each of these enzymes with its substrate(s), coenzymes, and inhibitors.

[The effect of different centrifugation conditions in the isolation of mixed rumen bacteria on their content of nitrogen and diaminopimelic acid: use of duodenal content as raw material]

The objective of the present study was, to investigate the effect of varying conditions of differential centrifugation of duodenal content on the isolation of bacteria (B-fraction) and feed particles + protozoa (FP-fraction). The treatments at low-speed centrifugation were as follows: 100 x g/5 min, 400 x g/10 min, 1000 x g/10 min and 2000 x g/10 min, high speed conditions were 30,000 x g/30 min/4 degrees C. The results of three experiments are given. Analytical examination gave similar results for N-contents for all treatments, the mean values being 7.90 +/- 0.27% (n = 12) for B-fractions and 6.53 +/- 0.73% (n = 12) for FP-fractions. Increasing the low-speed from 100 x g to 2000 x g lead to increasing DAP-contents and decreasing N:DAP-ratios of the bacterial isolates, the values being 2.43, 3.02, 3.22 and 3.39 mg DAP/g DM and 32.0, 27.4, 25.0 and 23.0 N:DAP-ratio. Decreased isolation of bacterial material in the B-fraction in conjunction with increased incorporation in the FP-fraction resulted in rising the speed of the low speed centrifugation. The rates of loss of DAP, measured by comparison with the total amount were 10, 32, 48 and 70% respectively. It was concluded to prefer the isolation of bacteria from rumen fluid.

[The effect of different centrifugation conditions for the isolation of mixed rumen bacteria, on their nitrogen and diaminopimelic acid content]

Three cows were given two rations, a silage diet (3 animals) and a green forage diet (2 animals). Samples of rumen content were collected and aliquots of these were separated in a fraction of feed particles and protozoa (FP-fraction) and a fraction of mixed bacteria, varying the conditions of differential centrifugation. The low speed centrifugation was practised at 100 X g/5 min, 400 X g/10 min, 1000 X g/10 min, and 2000 X g/10 min. High speed conditions were 30,000 X g/30 min 4 degrees C. The lyophylisated sediments were used for determination of N and DAP. The content of N gave similar results for all fractions of mixed bacteria, the mean value being 7.43 +/- 0.48% (n = 20), while the N-content of the FP-fractions being 5.68 +/- 0.37% (n = 19). The N:DAP-ratio gave similar values for the cows fed the silage diet, the values were 29.45 +/- 1.56 (n = 12). The values for the cows receiving the green forage diet differed, the mean values were 23.08 +/- 0.88 and 42.01 +/- 5.81 (n = 5), respectively. In all five experiments highest ratios were found at 100 X g. Further investigations showed that storage at -20 degrees C rumen fluid after isolation of feed particles and protozoa decreased both the N- and DAP- content without affecting the N:DAP-ratio. Centrifugation at low speed with 100 X g resulted in a markedly decreased contamination with DAP in all the FP-fractions. Optimal conditions for separation of feed particles and protozoa from rumen fluid to get a fraction best reflecting the rumen bacterial populations are 100 X g/5 min.

[Lysine biosynthesis of Pseudomonas aeruginosa PAO1. III. Further characterization of lysine auxotrophic mutant of Ps. aeruginosa PAO1]

A number of lysine-auxotrophic mutants of Pseudomonas aeruginosa PAO1 were isolated through mutagenesis by means of N-methyl-N-nitrosoguaniine (Mach et al., unpublished). Using the cross feeding test and growth tests classification of lysine mutants was not possible. The investigation of diaminopimelic acid decarboxylase (DAP-DC) showed, that none of these mutants had an active enzyme, except for the mutants with a high number of revertants. The appearance of only one mutant type is attributed to the insufficient availability of DAP.

Characterization of a stable L-form of Bacillus subtilis 168

A stable L-form of Bacillus subtilis 168 (sal-1) has been isolated which grows and divides logarithmically in liquid medium with a generation time of 60 min. This mutant does not synthesize cell wall as evidenced by chemical, biochemical, and morphological analyses. Antibiotics which specifically inhibit cell wall biosynthesis do not affect the growth of the L-form. Significant differences exist between the membrane proteins of the bacillary form and the L-form. The relative profile of membrane proteins varies with the salt concentration of the medium in both the L-form and the bacillary form.

The effect of dietary content of plant protein on the utilization of urea in the bovine rumen

1. Four young Friesian bulls with rumen fistulas were given four isocaloric all-concentrate diets containing different amounts and sources of nitrogen in a Latin square arrangement. Diet HP (high-protein) contained 2·31% plant nitrogen; diet MPU (medium-protein with urea) 1·67% plant nitrogen and 0·69% urea nitrogen (total 2·36%); diet LPU (low-protein with urea) 0·95% plant nitrogen and 0·69% urea nitrogen (total 1·65%); diet HPU (high-protein with urea) 2·28% plant nitrogen and 0·69% urea nitrogen (total 2·97%), calculated on an air-dry basis.

2. The rumen pH varied between 5·8 and 6·1 with diets HP, MPU and HPU, but was significantly lower with diet LPU with values between 5·4 and 5·8.

3. The results showed no differences between the isonitrogenous diets HP and MPU except that replacement of plant nitrogen with urea was followed by an increase in the concentration of ammonia in the rumen. With the diets containing urea, the concentrations of rumen ammonia varied inversely with the amount of dietary plant nitrogen supplied, indicating a negative effect of plant nitrogen on urea utilization.

4. Concentrations of alkali-labile nitrogen (amide) were not increased with diets containing urea except with diet HPU, which produced the highest concentrations of ammonia in the rumen.

5. The concentration of true protein in the rumen and the amino acid distribution were similar with all four diets, indicating the ability of the microflora to adapt to qualitative and quantitative differences in dietary nitrogen intake.

6. Ration acceptability was lower with diets LPU and HPU than with diets HP and MPU.

7. Large differences between individual animals in rumen pH, percentage of dry matter and total nitrogen concentration in the rumen were noted.

α-Aminoadipic Acid and α,ɛ-Diaminopimelic Acid in Inoculated Pea Plants (Pisum sativum) and Root Nodule Bacteria (Rhizobium leguminosarum)

Observations were made on the content of α-aminoadipic acid and α-aminophimelic acid (DAP) in pea plants, nodules and Rhizobium leguminosarum, strain HT3. The preparations were purified by ion exchange chromatography, Qualitative analyses were made by paper chromatography, and quantitative analyses by means of an automatic amino acid analysator. In the whole plant and seeds the content of α-aminoadipic acid soluble in 70% ethanol varied between 10 and 80 μg/g dry weight. The shoot and red nitrogen fixing nodules contained more of this acid than roots and green inactive nodules. In the insoluble fraction of the shoot its concentration was 0.4-0.6 mg/g dry weight. α-Aminoadipic acid was not found in free living rhizobia, which again contained a considerable amount of α-aiaminopimelic acid, about 0.5 mg/g dry weight. The synthesis of DAP was intensive also in root nodules. In red nodules, which fixed molecular nitrogen, the content of DAP was 2.1 mg/g dry weight and in green inactive nodules 1.3 mg/g dry weight. It was shown that in the nodules DAP is closely connected with cell wall peptides of bacteroids. DAP could not be found in pea plants outside the nodules.

Pentitols and insulin release by isolated rat islets of Langerhans

1. Insulin secretion was studied in isolated islets of Langerhans obtained by collagenase digestion of rat pancreas. In addition to responding to glucose and mannose as do whole pancreas and pancreas slices in vitro, isolated rat islets also secrete insulin in response to xylitol, ribitol and ribose, but not to sorbitol, mannitol, arabitol, xylose or arabinose. 2. Xylitol and ribitol readily reduce NAD(+) when added to a preparation of ultrasonically treated islets. 3. Adrenaline (1mum) inhibits the effects of glucose and xylitol on insulin release. Mannoheptulose and 2-deoxy-glucose, however, inhibit the response to glucose but not that to xylitol. 4. The intracellular concentration of glucose 6-phosphate is increased when islets are incubated with glucose but not with xylitol, suggesting that xylitol does not promote insulin release by conversion into glucose 6-phosphate. 5. Theophylline (5mm) potentiates the effect of 20mm-glucose on insulin release from isolated rat islets of Langerhans, but has no effect on xylitol-mediated release. These results indicate that xylitol does not stimulate insulin release by alterations in the intracellular concentrations of cyclic AMP. 6. A possible role for the metabolism of hexoses via the pentose phosphate pathway in the stimulation of insulin release is discussed.

Dipicolinic acid synthesis in Penicillium citreo-viride

Hodson, Phillip H. (University of Texas, Austin), and J. W. Foster. Dipicolinic acid synthesis in Penicillium citreo-viride. J. Bacteriol. 91:562-569. 1966.-Dipicolinic acid (DPA) accumulation in culture filtrates of the mold Penicillium citreo-viride was studied in surface and submerged cultures. Good DPA yields were obtained in suspensions of washed, submerged mycelium in the presence of a carbon and a nitrogen source but in the absence of other minerals essential for growth. Fumaric acid was the only other acid formed in significant amounts. Glucose and glycerol were superior to various salts of organic acids as carbon sources, and certain amino acids were excellent nitrogen sources. l-Leucine, l-norvaline, l-tyrosine, and l-histidine were superior to urea, NH(4)Cl, or NaNO(3) as nitrogen precursors for DPA production. d-Norvaline was useless for DPA production. Glycerol-2-C(14) and -1-C(14), C(14)O(2), and l-leucine-C(14), l-tyrosine-C(14), and l-histidine-C(14) were tested as precursors in conjunction with suitable carbon and nitrogen sources. The DPA was decarboxylated chemically, and the distribution of C(14) was determined in the pyridine-C and in the carboxyl-C. The data are consistent with Martin and Foster's suggestion for bacteria that the DPA molecule is formed by a condensation of C(3) plus C(4) precursors, the resulting 2-keto, 6-aminopimelic acid derivate undergoing ring closure to form a heterocyclic precursor of DPA. The C(14)O(2) experiments indicate that oxaloacetate is formed by beta-carboxylation of pyruvate, this in turn probably becoming aspartic acid beta-semialdehyde, the C(4) compound which condenses with a second pyruvate. The enhancement of DPA formation by l-norvaline, l-leucine, and l-histidine is not ascribable to their functioning either as a source of nitrogen or carbon. l-Tyrosine, in a glycerol medium, contributed nearly 40% of the DPA carbon. The mechanism of biosynthesis of C(7) straight-chain and cyclic compounds is discussed.

Method for measuring diaminopimelic acid in total rumen contents and its application to the estimation of bacterial growth

Diaminopimelic acid (DAP) was measured in rumen samples for which growth rate had previously been estimated from changes in fermentation capacity. The growth measurements by the two methods agreed within the experimental error. Agreement between the rate of bacterial growth (DAP) and total microbial growth (fermentation capacity) suggests that the protozoa also grow at about this rate.

Site of action of certain antibacterial heterocyclic quaternary ammonium compounds

The site of action of related mono- and bis-quinaldinium compounds was investigated in Staphylococcus aureus and Bacillus megaterium. The effects of these compounds on cell morphology and on protoplast formation and fragility were studied, and the distribution of C(14)-labeled quinaldinium compound in cell fractions was measured. The latter studies showed that a major part of the quaternary compound penetrates the cell, leaving a very small quantity associated with the cell wall. Similar antibacterial effects were seen with both the mono- and bis-quinaldinium compounds studied, and these effects were comparable with antibacterial properties of known cationic surface-active antibacterial agents.

The biochemistry of the Actinomycetales: studies on the cell wall of Streptomyces fradiae

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