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At least 19 recordsLinked to original sources
PubMed1978

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↗
PubMed1980

Detection of polyphosphates and enzymes of polyphosphate metabolism in Bdellovibrio bacteriovorus.

Bdellovibrio bacteriovorus cells, parasitizing in E. coli, contain a considerable amount of inorganic polyphosphates, 55% of the total pool of which is due to the most polymeric acid-insoluble polyphosphates. B. bacteriovorus contains enzymes participating both in the synthesis and consumption of polyphosphates, i.e. 1,3-diphosphoglycerate: polyphosphate phosphotransferase, polyphosphate glucokinase, polyphosphatase, tripolyphosphatase, pyrophosphatase, acid and alkaline phosphatases. The possible role of high-molecular polyphosphates in the vital activity of the bacterial parasite B. bacteriovorus is discussed.

Bdellovibrio↗
PubMed1982

Periplasmic enzymes in Bdellovibrio bacteriovorus and Bdellovibrio stolpii.

When cells of either Bdellovibrio bacteriovorus 109J or Bdellovibrio stolpii UKi2 were subjected to osmotic shock by treatment with sucrose-EDTA and MgCl2 solutions, only trace amounts of proteins or enzyme activities were released into the shock fluid. In contrast, when nongrowing cells were converted to motile, osmotically stable, peptidoglycan-free spheroplasts by penicillin treatment, numerous proteins were released into the suspending fluid. For both species, this suspending fluid contained substantial levels of 5'-nucleotidase, purine phosphorylase, and deoxyribose-phosphate aldolase. Penicillin treatment also released aminoendopeptidase N from B. bacteriovorus, but not from B. stolpii. Penicillin treatment did not cause release of cytoplasmic enzymes such as malate dehydrogenase. The data indicated that bdellovibrios possess periplasmic enzymes or peripheral enzymes associated with the cell wall complex. During intraperiplasmic bdellovibrio growth, periplasmic and cytoplasmic enzymes of the Escherichia coli substrate cell were not released upon formation of the spherical bdelloplast during bdellovibrio penetration. Most of the E. coli enzymes were retained within the bdelloplast until later in the growth cycle, when they became inactivated or released into the suspending buffer or both.

5'-Nucleotidase↗
PubMed1977

Osmoregulation in symbiosis-independent mutants of Bdellovibrio bacteriovorus.

Bdellovibrios capable of axenic growth grow in a cell-free medium at a rate considerably lower than that attainable in a two-membered culture with Escherichia coli. The axenic growth rate may be improved either by adjustment of the osmosity of the medium or by the addition of low concentrations of spermine.

Bdellovibrio↗
PubMed1977

Effect of light on Bdellovibrio bacteriovorus.

Bdellovibrio underwent photooxidation by visible light in the presence of exogenous photosensitizer and by near-ultraviolet light (325 to 400 nm) in its absence. The colorless, host-dependent wild type was more sensitive to the lethal effect of light than was its pigmented, facultative parasitic mutant. The latter's ability to form colonies was much more sensitive to light than was its plaque-forming capability. The biosynthesis of the mutant pigment was inhibited by diphenylamine, though this inhibition did not result in additional sensitivity to photokilling.

Bdellovibrio↗
PubMed1998

Developmentally regulated protein synthesis during intraperiplasmic growth of Bdellovibrio bacteriovorus 109J.

Bdellovibrio bacteriovorus 109J is an obligate intraperiplasmic predator of other Gram-negative bacteria. Collision with a suitable prey cell initiates a developmental sequence ultimately resulting in the destruction of the prey cell and the production of progeny bdellovibrios. Two-dimensional gel analysis of patterns of protein synthesis at various times in a synchronously growing culture of Bdellovibrio bacteriovorus 109J revealed over 30 polypeptides whose syntheses are developmentally regulated. The majority of these polypeptides fall into nine categories: attack phase specific or one of eight different kinetic groups expressed during the intraperiplasmic growth phase. The results indicate that Bdellovibrio bacteriovorus 109J has a complex system for regulating gene expression during its developmental cycle.

Bacterial Proteins↗
PubMed1969

Interaction of Bdellovibrio bacteriovorus and host bacteria. II. Intracellular growth and development of Bdellovibrio bacteriovorus in liquid cultures.

The intracellular life cycle of Bdellovibrio bacteriovorus 109 growing on Escherichia coli in a dilute nutrient medium exhibits a period of constant infective titer while the parasite grows and elongates inside the host cell. This period is terminated after 2 to 4 hr, and the number of the plaque-forming units in the culture rises rapidly to as much as six times the initial titer. The growth pattern of Bdellovibrio is similar with actively growing or resting host cells, or with host cells killed by ultraviolet irradiation or by heating at 70 C. The yield of B. bacteriovorus strain 109 in two-membered cultures with E. coli B depends on the host concentration and may reach 7.5 x 10(10) cells per ml. Penicillin, which has no effect on the attachment and penetration of Bdellovibrio, inhibits its multiplication.

Bacteria↗
PubMed2006

Differential predation by Bdellovibrio bacteriovorus 109J.

Bdellovibrio bacteriovorus is a predatory bacterium that can replicate only inside Gram-negative bacteria. We incubated B. bacteriovorus 109J in a mixture of two prey cells present in equal numbers and enumerated prey cells after 3 h of predation. In multiple prey pairings, B. bacteriovorus preferentially lysed on one prey over the other. When prey were individually incubated with B. bacteriovorus, they were preyed on with different efficiencies. Three prey had only 5-8% of cells remaining after Bdellovibrio predation and the other three prey had 37-43% of cells remaining. Timing of attachment of B. bacteriovorus to prey cells also varied with Bdellovibrio attachment to more preferred prey occurring the fastest. These results suggest that B. bacteriovorus 109J does not randomly infect prey cells but infects and kills some prey more readily than others.

Antibiosis↗
PubMed1968

Interacton of Bdellovibrio bacteriovorus and host bacteria. I. Kinetic studies of attachment and invasion of Escherichia coli B by Bdellovibrio bacteriovorus.

Quantitative methods were developed for the study of the early stages in the interaction of Bdellovibrio bacteriovorus and host bacteria. Attachment measurements were based on the differential filtration of host and parasite. Invasion was measured by estimation of radioactively labeled Bdellovibrio cells remaining attached to the host cells after mechanical agitation. The kinetics of attachment and the final number of Bdellovibrio cells attached were dependent on the multiplicity of the parasite, the composition and pH of the medium, and the incubation temperature. Inhibitors of Bdellovibrio motility, including chelating agents, NaN(3), and low pH, all inhibited attachment, as did anaerobiosis. Ultraviolet-killed host cells retained their competence for attachment of Bdellovibrio cells, whereas heat-killed cells lost it. Invasion was selectively inhibited by inhibitors of protein synthesis, such as streptomycin, puromycin, and chloramphenicol. These antibiotics had no effect on attachment.

Azides↗
PubMed1993

Heat shock-induced axenic growth of Bdellovibrio bacteriovorus.

The bdellovibrios are obligately predatory bacteria that attack other gram-negative bacteria. They grow only in the periplasmic space of prey unless they mutate to forms that can grow axenically. A culture medium that promoted enhanced growth of prey-independent bdellovibrios was developed. The ability of this medium to support the growth of prey-dependent bdellovibrios was tested under transcription-altering conditions. This approach tested the hypothesis that the inability to grow prey-dependent bdellovibrios in artificial media was rooted in both nutritional and transcriptional signal deficiencies. It was assumed that nutritional deficiencies had been resolved and that empirically applied artificial signals may evoke the expression of genes required for axenic growth of bdellovibrios. Prey-dependent bdellovibrios could be grown in PPYE medium (0.1% proteose peptone 3 and 0.03% Bacto yeast extract adjusted to pH 7.0 and supplemented with 3 mM MgCl2 and 2 mM CaCl2 after autoclaving) after heat shock, and subsequent rounds of growth occurred after additional heat shocks. Heat shock may have generated or simulated signals normally derived from prey.

Bacteriological Techniques↗
PubMed1981

Incorporation of substrate cell lipid A components into the lipopolysaccharide of intraperiplasmically grown Bdellovibrio bacteriovorus.

The composition of Bdellovibrio bacteriovorus lipopolysaccharide (LPS) was determined for cells grown axenically and intraperiplasmically on Escherichia coli or Pseudomonas putida. The LPS of axenically grown bdellovibrios contained glucose and fucosamine as the only detectable neutral sugar and amino sugar, and nonadecenoic acid (19:1) as the predominant fatty acid. Additional fatty acids, heptose, ketodeoxyoctoic acid, and phosphate were also detected. LPS from bdellovibrios grown intraperiplasmically contained components characteristic of both axenically grown bdellovibrios and the substrate cells. Substrate cell-derived LPS fatty acids made up the majority of the bdellovibrio LPS fatty acids and were present in about the same proportions as in the substrate cell LPS. Glucosamine derived from E. coli LPS amounted to about one-third of the hexosamine residues in intraperiplasmically grown bdellovibrio LPS. However, galactose, characteristic of the E. coli outer core and O antigen, was not detected in the bdellovibrio LPS, suggesting that only lipid A components of the substrate cell were incorporated. Substrate cell-derived and bdellovibrio-synthesized LPS materials were conserved in the B. bacteriovorus outer membrane for at least two cycles of intraperiplasmic growth. When bdellovibrios were grown on two different substrate cells successively, lipid A components were taken up from the second while the components incorporated from the lipid A of the first were conserved in the bdellovibrio LPS. The data show that substrate cell lipid A components were incorporated into B. bacteriovorus lipid A during intraperiplasmic growth with little or no change, and that these components, fatty acids and hexosamines, comprised a substantial portion of bdellovibrio lipid A.

Bdellovibrio↗
PubMed1975

Utilization of nucleoside monophosphates per Se for intraperiplasmic growth of Bdellovibrio bacteriovorus.

During growth of Bdellovibrio bacteriovorus on Escherichia coli, there was a marked preferential use of E. coli phosphorus over exogenous orthophosphate even though the latter permeated into the intraperiplasmic space where the bdellovibrio was growing. This preferential use occurred to an equal extent for lipid phosphorus and nucleic acid phosphorus. Exogenous thymidine-5'-monophosphate competed effectively with [3H]thymine residues of E. coli as a precursor for bdellovibrio deoxyribonucleic acid; exogenous thymidine competed less effectively and thymine and uridine not at all. A mixture of exogenous nucleoside-5'-monophosphates equilibrated effectively with E. coli phosphorus as a phosphorus source for B. bacteriovorus; the nucleotide phosphorus entered preferentially into bdellovibrio nucleic acids. A comparable mixture of exogenous nucleosides plus orthophosphate had only a small effect on utilization of E. coli phosphorus by B. bacteriovorus, as did orthophosphate alone. A mixture of exogenous deoxyriboside monophosphates equilibrium effectively with E. coli phosphorus as a phosphorus source for bdellovibrio growth; the phosphorus from this source entered preferentially into deoxyribonucleic acid. These data show that nucleoside monophosphates derived from the substrate organism are utilized directly for n-cleic acid biosynthesis by B. bacteriovorus growing intraperiplasmically. As a consequence, the phosphate ester bonds preexisting in the nucleic acids of the substrate organism are conserved by the bdellovibrio, presumably lessening its energy requirement for intraperiplasmic growth. The data also suggest, but do not prove, that the phosphate ester bonds of phospholipids are also conserved.

Bacteria↗
PubMed1992

Acquisition of apparently intact and unmodified lipopolysaccharides from Escherichia coli by Bdellovibrio bacteriovorus.

The ability of Bdellovibrio bacteriovorus to relocalize the OmpF major outer membrane porins from its Escherichia coli prey to its own outer membranes is diminished in prey expressing smooth lipopolysaccharide (S-LPS). Since porins exist in the membrane complexed with LPS, we examined the LPS associated with relocalized porin to determine whether it had been acquired intact, mixed or replaced with Bdellovibrio LPS, or derivatized by the bdellovibrios. The relocalized trimers were found associated with the same LPS originally bound to them in the E. coli. The bulk-phase LPS from bdellovibrios grown on various chemotypes of rough prey was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to determine whether more than the trimer-bound LPS was acquired by the bdellovibrios. This analysis revealed bands of Bdellovibrio LPS matching the LPS chemotype of the prey. One or two other bands were identical in migration to the LPS of prey-independent mutants of B. bacteriovorus and represented bdellovibrio-synthesized LPS. The LPS of bdellovibrios grown on prey with radiolabeled lipid A showed radioactivity only in gel band positions identical with those of the prey's LPS. The amount of this prey-derived LPS was shown by enzyme-linked immunosorbent assay to reach a constant value during the purification of the bdellovibrios, and it represented approximately 25% of the total Bdellovibrio LPS. Immunoelectron microscopy confirmed the presence of prey-derived LPS on the cell surface of bdellovibrios, and no evidence could be found for bdellovibrio-induced modifications of the relocalized prey LPS.

Bacterial Outer Membrane Proteins↗
PubMed1970

Facultatively parasitic strain of Bdellovibrio bacteriovorus.

A strain of Bdellovibrio bacteriovorus (designated strain UKi2) was isolated which was capable of growing either saprophytically in host-free medium or endoparasitically in Escherichia coli B/r. It was quantitatively determined that each bdellovibrio could develop in solid medium to produce a colony, and 65% of the cells in a late exponential-phase culture were capable of inducing E. coli B/r spheroplasts. A photomicrographic sequence of single E. coli spheroplasts containing bdellovibrios demonstrated that parasitically derived B. bacteriovorus UKi2 could develop saprophytically after release from the host cells. Strain UKi2 appears to be morphologically quite similar to previously described obligately parasitic bdellovibrios; biochemical data on this strain suggests its close relationship to some of the previously described host-independent strains of Bdellovibrio.

Bacteria↗
PubMed1975

Ribonucleic acid destruction and synthesis during intraperiplasmic growth of Bdellovibrio bacteriovorus.

During growth of Bdellovibrio bacteriovorus on (2-14C)uracil-labeled Escherichia coli approximately 50% of the radioactivity is incorporated by the bdellovibrio and most of the remainder is released as free nucleic acid bases. Kinetic studies showed that 50 and 30S ribosomal particles and 23 and 16S ribosomal ribonucleic acid (RNA) of E. coli are almost completely degraded by the first 90 min in a 210- to 240-min bdellovibrio developmental cycle. Synthesis of bdellovibrio ribosomal RNA was first detected after 90 min. The specific activity and the ratio of radioactivity in the bases of the synthesized bdellovibrio RNA was essentially the same as those of the substrate E. coli. The total radioactivity of the bdellovibrio deoxyribonucleic acid (DNA) exceeded that in the DNA of the substrate E. coli cell, and the ratio of radioactivity of cytosine to thymine residues differed. Intraperiplasmic growth of B. bacteriovorus in the presence of added nucleoside monophosphates (singly or in combination) significantly decreased the uptake of radioactivity from (2-14C)uracil-labeled E. coli; nucleosides or nucleic acid bases did not. It is concluded that the RNA of the substrate cell, in the form of nucleoside monophosphates, is the major or exclusive precursor of the bdellovirbrio RNA and also serves as a precursor for some of the bdellovibrio DNA.

Bacteria↗
PubMed2006

Characterizing the flagellar filament and the role of motility in bacterial prey-penetration by Bdellovibrio bacteriovorus.

The predatory bacterium Bdellovibrio bacteriovorus swims rapidly by rotation of a single, polar flagellum comprised of a helical filament of flagellin monomers, contained within a membrane sheath and powered by a basal motor complex. Bdellovibrio collides with, enters and replicates within bacterial prey, a process previously suggested to firstly require flagellar motility and then flagellar shedding upon prey entry. Here we show that flagella are not always shed upon prey entry and we study the six fliC flagellin genes of B. bacteriovorus, finding them all conserved and expressed in genome strain HD100 and the widely studied lab strain 109J. Individual inactivation of five of the fliC genes gave mutant Bdellovibrio that still made flagella, and which were motile and predatory. Inactivation of the sixth fliC gene abolished normal flagellar synthesis and motility, but a disordered flagellar sheath was still seen. We find that this non-motile mutant was still able to predate when directly applied to lawns of YFP-labelled prey bacteria, showing that flagellar motility is not essential for prey entry but important for efficient encounters with prey in liquid environments.

Bdellovibrio↗
PubMed1970

Early host damage in the infection cycle of Bdellovibrio bacteriovorus.

The effects of bdellovibrio infection on host permeability and respiration were investigated by measuring respiration rates and the rate of o-nitrophenyl-beta-d-galactopyranoside hydrolysis during the course of single infection cycles of Bdellovibrio bacteriovorus strain 109 growing on Escherichia coli ML 35 (lac i(-)z(+)y(-)). The data show that among the very early consequences of parasite attack on the host are an increase in permeability and a general disruption of respiratory activity of the host, and it is suggested that both phenomena stem from early damage to host membrane. The rapid onset of damage after inception of the cycle and the failure of streptomycin to prevent the damage indicate that complete penetration of the parasite into the host is not a requirement for the observed effects. The data also show that bdellovibrio does not use host energy-generating mechanisms for its growth and suggest that the parasites may have a search mechanism that permits them, to some degree, to distinguish between infected and uninfected hosts.

Bacteria↗
PubMed1976

Membrane-associated, energy-linked reactions in Bdellovibrio bacteriovorus.

Disrupted cells of Bdellovibrio bacteriovorus exhibited adenosine triphosphatase activity, 60 to 80% of which was in the soluble fraction. Dicyclohexylcarbodiimide did not inhibit the adenosine triphosphatase activity in membrane particles. The particles did not show energy-linked transhydrogenase activity. The activity of non-energy-linked transhydrogenase as well as the rate of oxygen consumption were higher in membrane particles of the host-independent strain than in the host-dependent strains. The uptake of amino acid uptake was inhibited by cyanide and by carbonyl cyanide p-trifluoromethoxyphenyl hydrazone. Valinomycin, in the presence of K+, did not inhibit the uptake, and only partial inhibition was exerted by arsenate and dicyclohexylarbodiimide. Sulfhydryl reagents inhibited amino acid uptake.

Adenosine Triphosphatases↗