Putative structure and functions of a poly-beta-hydroxybutyrate/calcium polyphosphate channel in bacterial plasma membranes.

A poly-beta-hydroxybutyrate complex extracted from the plasma membranes of genetically competent Escherichia coli contained polyhydroxybutyrate:polyphosphate:calcium in molar ratios approximating 1:1:0.5. The chain length of the polyhydroxybutyrate was estimated as 120-200 subunits, and that of the polyphosphate was estimated as 130-170 subunits.

Protein synthesis during encystment of Azotobacter vinelandii.

Proteins synthesized during the encystment of Azotobacter vinelandii were radiolabeled with [35S]methionine and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Pulse labeling was used to demonstrate that early encystment-specific proteins were beginning to be synthesized at 2 h and reached peak levels about 12 h after initiation of encystment. One such protein was identified as a beta-ketoacyl acyl-carrier protein synthase.

Protein turnover in Azotobacter vinelandii during encystment and germination.

Protein turnover occurs during differentiation of Azotobacter vinelandii 12837 to the extent of 50% during encystment and 7% during germination. The addition of rifampin at the initiation of encystment prevents encystment and inhibits turnover. In germinating cysts, protein turnover is essential owing to an apparent lack of certain amino acid biosynthetic enzymes.

D-(-)-poly-beta-hydroxybutyrate in membranes of genetically competent bacteria.

D-(-)-Poly-beta-hydroxybutyrate is a constituent of the membranes and the cytoplasms of genetically competent Azotobacter vinelandii, Bacillus subtilis, and Haemophilus influenzae cells. Within each species the concentration of D-(-)-poly-beta-hydroxybutyrate in the membranes and cytoplasm correlates with transformability. Fluorescence analysis of the thermotropic lipid phase transitions in A.

Novel lipid components of the Azotobacter vinelandii cyst membrane.

Phospholipids are ubiquitous components of biological membranes. In the vegetative cells of Azotobacter vinelandii, a Gram-negative free-living aerobic soil bacterium, the membrane lipids are phospholipids with polar head group and fatty acyl compositions similar to those of Escherichia coli. We report here that when A.

Unique lipids in Azotobacter vinelandii cysts: synthesis, distribution, and fate during germination.

Unique lipids found in Azotobacter vinelandii cysts are derived primarily from beta-hydroxybutyrate used to induce encystment. Tracer studies with beta-[14C]hydroxybutyrate showed that the biosynthesis of these compounds during encystment began at 8 to 12 h after induction and reached maximal levels after 2 days, Seventy percent of these unique lipids were found in the central body of the cysts, and 23% were found in the exine. Pyronic compounds, which are located mostly in the central body, were degraded during germination of the cysts, but little change occurred in the phenolic compounds, which are more uniformly distributed in the cysts.

Isolation and characterization of several unique lipids from Azotobacter vinelandii cysts.

Unique cyclic compounds were found in the lipid fraction of Azotobacter vinelandii cysts. In addition to two major molecular species which had already been identified, 5-n-alkylresorcinol and its galactoside derivative, five other molecular species (two alkyl side chain homologs of each) were isolated, and their structures were established by infrared, ultraviolet, nuclear magnetic resonance, and mass spectroscopy. These 10 compounds were 6-n-heneicosylresorcylic acid methyl ester and 6-n-tricosylresorcylic acid methyl ester, 5-n-(2-hydroxy)heneicosylresorcinol and 5-n-(2-hydroxy-tricosylresorcinol, 5-n-heneicosyl-4-acetylresorcinol and 5-n-tricosyl-4-acetylresorcinol, 6-n-heneicosyl-4-hydroxypyran-2-one and 6-n-tricosyl-4-hydroxypyran-2-one, and 6-(2-oxotricosyl)-4-hydroxy-pyran-2-one and 6-(2-oxopentacosyl)-4-hydroxypyran-2-one.

Lipid metabolism during encystment of Azotobacter vinelandii.

The formation of cysts by Azotobacter vinelandii involves the synthesis of lipids as major metabolic products. Cells which encyst at low levels in aging glucose cultures undergo the same pattern of lipid synthesis as cells which undergo reasonably synchronous encystment in beta-hydroxybutyrate or n-butanol. The accumulation of poly-beta-hydroxybutyrate (PHB) precedes the synthesis of 5-n-heneicosylresorcinol and 5-n-tricosylresorcinol (AR1), which is then followed in about 6 h by the synthesis of the 5-n-alkylresorcinol galactosides (AR2).

5-n-Alkylresorcinols from encysting Azotobacter vinelandii: isolation and characterization.

Azotobacter vinelandii was found to form novel lipid compounds when encystment was initiated by 0.2% beta-hydroxybutyrate. An examination of these compounds led to the isolation and characterization of 5-n-heneicosylresorcinol, 5-n-tricosylresorcinol, and their galactoside derivatives.

Characterization of Azotobacter vinelandii deoxyribonucleic acid and folded chromosomes.

The properties of Azotobacter vinelandii deoxyribonucleic acid (DNA) and folded chromosomes were studied and compared to those of Escherichia coli as a standard. Based on melting temperature and buoyant density measurements, the guanosine + cytosine content of purified A. vinelandii DNA was 65%, whereas that of E.

Physiological studies of a temperature-sensitive sporulation mutant of Bacillus cereus T.

Growth of temperature-sensitive mutant Bacillus cereus T JS22-C occurred normally at the restrictive temperature (37 degrees C), but sporulation was blocked at stage 0. The production of extracellular and intracellular proteases and of alkaline phosphatase occurred at 37 degrees C, but the expression of a functional tricarboxylic acid cycle did not. At the permissive temperature (26 degrees C), the mutant sporulated at a slightly lower frequency (60%) and at a lower rate than the parent strain.

Fatty acids in phospholipids of cells, cysts, and germinating cysts of Azotobacter vinelandii.

Cyclopropane fatty acids constitute 25% of the phospholipid acyl groups in cysts of Azotobacter vinelandii. These are lost by dilution during germination when the synthesis of the fatty acids characteristic of vegetative cell phospholipids commences.

Ultrastructural and physiological changes occurring upon germination and outgrowth of Azotobacter vinelandii cysts.

Dormant cysts of Azotobacter vinelandii germinated at 30 degrees C in Burk nitrogen-free media containing 1% glucose. Samples taken at intervals and examined by electron microscopy revealed that as germination progressed, vesicle-like and fibrillar structures became visible in the intine region. Lamellae associated with the cell membrane appeared in the central body at 6 h post-initiation of germination.

In vitro production of bacitracin by proteolysis of vegetative Bacillus licheniformis cell protein.

The action of a sporulation-specific seryl protease on antibiotic-free extracts of Bacillus licheniformis cells yields a peptide that is identified as bacitracin by its biological activity, its spectral properties, and its comigration with genuine bacitracin in both paper and thin-layer chromatography. During proteolysis, a chemical structure is generated with the spectral properties of a delta-2 thiazoline ring. The yield in vitro, 4 microgram of bacitracin per mg of protein, is less than the maximal yield from sporulating cells, 75 microgram of bacitracin per mg of cell protein, but is a linear function of the amount of protein in the reaction system.

Purification of the extracellular protease of Bacillus licheniformis and its inhibition by bacitracin.

Sporulating cells of Bacillus licheniformis excrete three seryl proteases that are of similar size, 28,000 daltons, but of different charge at pH 6. The peptide antibiotic bactracin is released from the cells at the same time and exists, in part, as a bacitracin-protease complex that is stable throughout chromatographic procedures employed in enzyme purification. However, preextraction of crude protease with CHCl3 and subsequent gel filtration effect separation of the antibiotic and the enzyme.

Control of transformation competence in Azotobacter vinelandii by nitrogen catabolite derepression.

Azotobacter vinelandii (ATCC 12837) became competent to be transformed by exogenous deoxyribonucleic acid towards the end of exponential growth. Competence in wild-type and nitrogenase auxotrophic (nif-) strains was repressed by the addition of ammonium salts or urea to the transformation medium. Transformation of wild-type cells and nif- strains was optimal on nitrogen-free or nitrogen-limiting medium, respectively.

Physiological factors affecting transformation of Azotobacter vinelandii.

Cells of Azotobacter vinelandii (ATCC 12837) can be transformed by exogenous deoxyribonucleic acid towards the end of exponential growth. Transformation occurs at very low frequencies when the deoxyribonucleic acid is purified or when the transformation is carried out in liquid medium. Optimal transformation occurs on plates of Burk nitrogen-free glucose medium containing either high phosphate (10 mM) or low calcium (0 to 0.

Mechanisms of ampicillin resistance in Haemophilus influenzae type B.

The genetic mechanisms associated with ampicillin resistance in strains of Haemophilus influenzae type b were investigated. In experiments concerned with transfer of total deoxyribonucleic acid in vitro, expression of resistance by wild-type strains occurred at a frequency of about 10%. The minimum inhibitory concentration of ampicillin for the transformed strains was similar to that of the resistant donor strains, and resistance in transformants was associated with acquisition of the ability to produce beta-lactamase.

Relationship between calcium and uroinic acids in the encystment of Azotobacter vinelandii.

Encystment of Azotobacter vinelandii (ATCC 12837) in modified Burk nitrogen-free medium (pH 7.0) containing 0.2 percent beta-hydroxybutyrate occurs optimally in 0.

Tryptophan catabolism in Bacillus megaterium.

Bacillus megaterium grows in a medium containing L-tryptophan as the sole carbon, nitrogen, and energy source. Kynurenine, anthranilic acid, and catechol are metabolic intermediates, suggesting that this organism used the anthranilic acid pathway for tryptophan degradation. Cells that grow on L-tryptophan oxidize kynurenine, alanine, and anthranilic acid and the presence of tryptophan oxygenase (EC 1.

Transport of D- and L-tryptophan in Bacillus megaterium by an inducible permease.

Tryptophan-grown cells of Bacillus megaterium ATCC 19213 contain a permease system that transports both D- and L-tryptophan and is inhibited by sodium azide. Arginine-grown cells contain little tryptophan permease activity, suggesting that the system is inducible. Arginine represses the tryptophan permease as well as the transport system for leucine and phenylalanine.