Showing papers on "Bacteria published in 1970"
TL;DR: The contents and composition of pools from micro-organisms maintained in steady states in chemostat cultures did not vary with time, but changed significantly with changes in either growth rate or the nature of the growth limitation.
Abstract: SUMMARY: The free amino acid pool contents of Gram-negative bacteria (Aerobacter aerogenes, Erwinia carotovora, Pseudomonas fluorescens) were studied as functions of the growth environment and were compared with those from correspondingly grown cultures of Gram-positive bacteria (Bacillus subtilis var. niger, B. megaterium, B. polymyxa) and the yeast Saccharomyces cerevisiae.
Although the pools of the Gram-positive bacteria and the yeast contained five to 20 times the concentration of free amino acids present in the pools of Gram-negative bacteria, all pools were similar in containing only a limited range of detectable amino acids. Glutamate invariably predominated and generally accounted for over 50% of the total amino acid content of the pool. The contents and composition of pools from micro-organisms maintained in steady states in chemostat cultures did not vary with time, but changed significantly with changes in either growth rate or the nature of the growth limitation. However, these pool variations were small compared with those resulting from addition of 2% (w/v) NaCl to a culture of growing bacteria. With cultures of Gram-negative bacteria, sudden changes in medium salinity effected marked and rapid changes in free glutamate content; with Gram-positive bacteria, similar changes occurred, but extremely slowly. Addition of 4% (w/v) NaCl to growing yeast cultures brought about no observed changes in pool size or composition. These results are discussed with reference to the involvement of free amino acids in synthesis and functioning of microorganisms.
274 citations
TL;DR: The DNA base composition (GC content) of 114 strains belonging to the so-called coryneform bacteria was examined and a new method for the isolation of DNA from lysozyme-insensitive or poorly sensitive strains was described.
Abstract: The DNA base composition (GC content) of 114 strains belonging to the so-called coryneform bacteria was examined from the viewpoint of bacterial taxonomy. The GC content of these bacteria ranged widely from 46 to 78%. Although the GC content of Cellulomonas fell into a relatively narrow range near 72%, those of Corynebacterium, Arthrobacter, Microbacterium, and Brevibacterium did not exhibit the specific range to characterize the genus. This fact probably shows that the genera of coryneform bacteria, except Cellulomonas, are taxonomically heterogeneous. A new method for the isolation of DNA from lysozyme-insensitive or poorly sensitive strains was described.
231 citations
TL;DR: Selective destruction of teichoic acid reduces the ability of bacterial cell walls to bind Mg2+ ions.
Abstract: Selective destruction of teichoic acid reduces the ability of bacterial cell walls to bind Mg2+ ions.
229 citations
TL;DR: A motile flagellate ( fla(+)) variant of a fim(-)fla(-) strain of S. typhimurium outgrew its parent strain in mixed cultures in aerobic static broth, but the selective advantage conferred by motility was weaker than that conferred by fimbriation.
Abstract: Competitive mixed cultures were grown from inocula of a large number of bacteria of a genotypically nonfimbriate (fim−) strain of Salmonella typhimurium and a small number of a genotypically fimbriate (fim+) variant strain that formed type 1 fimbriae and had been derived from the fim− strain by phage transduction. The fim+ strain differed from the fim− strain in fermenting l-rhamnose (rha+), and the viable fim+ and fim− bacteria present in the cultures after different periods at 37 C were counted differentially in platings on rhamnose media. When the cultures were grown under aerobic static conditions in tubes of nutrient broth, the fim+ bacteria rapidly outgrew the fim− bacteria, so that, although starting as a small minority (e.g., 1 in 107), they approached or surpassed the number of the fim− in 48 hr. A pellicle consisting of fimbriate bacteria was formed on the surface of the broth between 6 and 24 hr, and it is thought that the advantage of access to atmospheric oxygen enjoyed by these bacteria in the pellicle enabled them to outgrow the fim− bacteria confined in the oxygen-depleted broth. The fim+ bacteria did not show selective outgrowth in mixed cultures grown in broth aerated by continuous shaking, in static broth incubated anaerobically in hydrogen, and on aerobic agar plates, i.e., under conditions not allowing an advantage from pellicle formation. The outgrowth of fim+ bacteria in aerobic static broth was prevented by the addition of α-methylmannoside, a substance that inhibits the adhesive and early pellicle-forming properties of bacteria with type 1 fimbriae. A motile flagellate (fla+) variant of a fim−fla− strain of S. typhimurium outgrew its parent strain in mixed cultures in aerobic static broth, but the selective advantage conferred by motility was weaker than that conferred by fimbriation.
222 citations
TL;DR: Although the phosphoenolpyruvate phosphotransferase system is an important system for the transport of sugars in bacteria carrying out anaerobic glycolysis, it plays no role in sugar transport by those organisms having a strictly oxidative physiology.
Abstract: A survey of the occurrence of the phosphoenolpyruvate-dependent glucose phosphotransferase system was carried out in a number of bacteria, representing both gram-positive and gram-negative facultative anaerobic and strictly aerobic types The system was found to be present in representatives of genera that are characteristically facultative anaerobes, but the system was absent in members of those genera that are strictly aerobic Thus, although the phosphoenolpyruvate phosphotransferase system is an important system for the transport of sugars in bacteria carrying out anaerobic glycolysis, it plays no role in sugar transport by those organisms having a strictly oxidative physiology A fundamentally different system, probably not involving phosphorylation during transport, is indicated in this latter group
164 citations
TL;DR: The results of these experiments suggest that the R6 DNA species banding in Proteus is the transfer unit while the species at ϱ = 1.718 g/cm3 contains the drug resistance markers, consistent with a model depicting certain R-factors as being composed of separately replicating, genetically independent units of DNA.
162 citations
TL;DR: The photosynthesis-light curve for purple sulfur bacteria had a steeper inclination than that for green sulfur bacteria at low light intensities, and the properties of the growth phase observed in lakes were similar to those calculated.
Abstract: The photosynthesis-light curve for purple sulfur bacteria had a steeper inclination than that for green sulfur bacteria at low light intensities. Light saturation occurred at intensities of S-7 klux in the former, in the latter at 10-30 klux. Light inhibition was observed in purple sulfur bacteria but was negligible in green sulfur bacteria. The optimal temperature for photosynthesis of these bacteria is considerably higher than that of most phytoplankton or green plants. Photosynthetic sulfur bacteria appear ordinarily in the contact layer between oxidative and reductive zones of meromictic or stagnant holomictic lakes; the light intensity in this contact layer is usually less than 10% of that at the surface. On the assmuption that the photosynthetic rate of these bacteria is limited mainly by the interaction of hydrogen sulfide concentration with light intensity, their growth was analyzed with a mathematical model. The properties of the growth phase observed in lakes were similar to those calculated. The main factors determining the growth of photosynthetic sulfur bacteria in lakes are the II23 concentration in the upper layer and the light conditions in the deeper layer.
131 citations
TL;DR: It is suggested that increased virulence is associated only with contact of amebae with live bacteria, and there may be the transfer of a factor from the bacteria to the isebae that alters virulence.
Abstract: Strains of E. histolytica from axenic cultures were studied with regard to their virulence and pathogenicity. Inoculation of amebae from axenic cultures into the liver of weanling hamsters did not result in hepatic abscesses. Reassociation of amebae with various bacterial strains resulted in hepatic abscess regularly when amebae and bacteria were reassociated for an interval of about 6 to 12 hours before inoculation into the liver. Loss of virulence upon axenization, however, was found to decline slowly over a period of from 3 to 5 months. In order to determine if there was some factor elaborated by, or associated with, bacteria that would cause increased amebic virulence, we added filtered bacterial cultures, bacteria killed by heat or X-radiation, or ground or sonicated bacteria to amebae from axenic cultures, which were then inoculated into livers of hamsters or guinea pigs. Hepatic abscess could not be produced by these methods. Similarly, growth of axenic amebae and bacteria in parabiotic chambers separated by a semipermeable membrane did not result in enhanced amebic virulence. These experiments suggest that increased virulence is associated only with contact of amebae with live bacteria. There may be the transfer of a factor from the bacteria to the amebae that alters virulence.
100 citations
TL;DR: Results from animal tests indicate that gibberellins A 3 has very low mammalian toxicity and that it occurs naturally in many, if not all, vegetable foodstuffs, in some cases in amounts greater than would occur from extraneous addition.
Abstract: Publisher Summary This chapter discusses fermentation aspects of the production of gibberellins It discusses the organisms that produce gibberellins, the structure of gibberellins, their biosynthesis, and production It provides a brief review of the applications to which their plant growth-promoting properties is also included The fungal gibberellins form part of a larger family of compounds, the other members being found in higher plants It is possible that gibberellins, or closely related compounds, are also produced by bacteria The intense studies which these fermentations have attracted have yielded a large number of compounds Some of these are implicated in the biosynthesis and breakdown of gibberellins while others are either “shunt” products or compounds, the presence of which would be expected on general metabolic considerations Results from animal tests indicate that gibberellins A 3 has very low mammalian toxicity and that it occurs naturally in many, if not all, vegetable foodstuffs, in some cases in amounts greater than would occur from extraneous addition It is to be expected that increasing applications will be found for this and other members of this interesting group of compounds
98 citations
TL;DR: With all bacterial mixtures tested, the intestinal E. coli population decreased, if at all, within a period of about 10 days after introduction of other bacteria, and remained stable thereafter, which suggests that the intestines of normal mice are controlled by a mechanism which reduces population size without affecting the growth rate.
Abstract: Strictly anaerobic and facultatively anaerobic bacteria were isolated from the intestinal tract of normal mice. Germ-free mice were associated with mixtures of varying complexity of pure cultures of these bacteria. The development of normal features in these animals was then determined on the basis of the following criteria: (i) size of the cecum, (ii) size of the Escherichia coli population in the cecum, (iii) histology of the intestinal tract, and (iv) development of a mucosa-associated flora in stomach and large intestine. Germ-free mice contaminated with cecal contents from conventional mice were used as controls to establish normal values for these parameters. Some strictly anaerobic bacteria could be implanted into germ-free mice only after prior implantation of an E. coli strain. E. coli was found in large numbers in stomach and cecum of mice monocontaminated with this organism. Use of restraining devices indicated that the E. coli population in the stomach was maintained by coprophagy and did not contribute significantly to the size of the cecal population. A mixture of 50 strictly anaerobic bacteria plus 80 facultative anaerobes rendered recipient animals normal with respect to the criteria tested. Other, less complex bacterial mixtures reduced the cecal size and the intestinal E. coli population to levels intermediate between those found in normal and germ-free mice. With all bacterial mixtures tested, the intestinal E. coli population decreased, if at all, within a period of about 10 days after introduction of other bacteria, and remained stable thereafter. This suggests that the intestinal E. coli population is controlled by a mechanism which reduces population size without affecting the growth rate.
96 citations
TL;DR: It is suggested that anaerobic conditions are necessary in vivo for optimal production and stability of cholanylglycine hydrolase from faecal bacteria.
TL;DR: Under controlled conditions, extracts of garlic, onion, turnip, green peppers and radishes were used to inhibit Escherichia coli, Salmonella typhosa, Shigella dysentriae and Staphylococcus aureus, which are all pathogenic bacteria.
Abstract: Under controlled conditions, extracts of garlic, onion, turnip, green peppers and radishes were used to inhibit Escherichia coli, Salmonella typhosa, Shigella dysentriae and Staphylococcus aureus, which are all pathogenic bacteria. It was found that 1–4% by vol. of garlic extract completely inhibited the growth of all the bacteria used. 4% by vol. of onion extract completely inhibited the growth of both Shigella dysentriae and Staphylococcus aureus at 10–6 dilution. Salmonella typhosa and E. coli were not completely inhibited; the inhibition was 48·3% for E. coli and 95·3% for Salmonella typhosa. At 10–4 bacterial dilution, onion extract decreased the colony number substantially in all four bacteria. 4% extracts from turnip, green peppers and radishes did not show a definite antibacterial action against any bacterium at the given dilutions. On the contrary some growth stimulating activity of these extracts on some bacteria was observed.
TL;DR: The ability to decompose choline is widespread among aerobic microorganisms since representatives of the genera Agrobacterium, Arthrobacter, Micrococcus, Pseudomonas, Rhizobium, and Streptomyces and a large number of coryneform bacteria were found to grow with choline as the sole C-and N-source as discussed by the authors.
Abstract: 1.
The ability to decompose choline is widespread among aerobic microorganisms since representatives of the genera Agrobacterium, Arthrobacter, Micrococcus, Pseudomonas, Rhizobium, and Streptomyces and a large number of coryneform bacteria were found to grow with choline as the sole C- and N-source.
2.
Almost all the coryneforms isolated from soil and dairy waste activated sludge displayed this ability in contrast to those isolated from cheese and, be it to a less extent, those from the phyllosphere. The significance of choline utilization in the taxonomy of coryneform bacteria is discussed.
3.
All the choline-utilizing bacteria tested were found to be able to grow with betaine, N,N-dimethylglycine, or sarcosine as the sole C- and N-source. Choline-grown cells, as contrasted to those grown with yeast extract and glucose, of Pseudomonas fluorescens and Arthrobacter S3 respired the latter three compounds at a rate similar to that of choline.
4.
About 30% of the 50 choline-utilizing coryneform bacteria tested grew also with N,N-dimethylethanolamine and N-monomethylethanolamine. Choline-grown cells, in contrast to those grown with yeast extract and glucose, of a representative of this group, Arthrobacter S3, also respired these two compounds at a rate somewhat lower than that of choline.
TL;DR: Nitrogen fixation has been obained with strains of Desulfovibrio vulgaris and D. gigas, organisms hitherto believed to be incapable of using molecular nitrogen, andfixation of N2 may be widespread in this genus of the sulphate-reducing bacteria.
Abstract: SUMMARY: Nitrogen fixation has been obained with strains of Desulfovibrio vulgaris and D. gigas, organisms hitherto believed to be incapable of using molecular nitrogen. Fixation has been demonstrated by increases in total nitrogen and by uptake of 15N2. Fixation of N2 may be widespread in this genus of the sulphate-reducing bacteria.
TL;DR: Seventy seven organic compounds have been tested for receptivity to attack by bacteria strains isolated from marine algae cultures, finding bacteria utilize amino and organic acids more frequently than sugars and derivatives.
Abstract: Seventy seven organic compounds have been tested for receptivity to attack by bacteria strains isolated from marine algae cultures. Bacteria utilize amino and organic acids more frequently than sugars and derivatives, especially when growth substances are not included in the experimental medium.
TL;DR: Nine out of seventeen strains of bacteria with a pronounced effect on seed germination and on seedling growth, isolated from root surfaces and rhizosphere soil of maize, were selected for a study on the formation of biologically active substances.
Abstract: Nine out of seventeen strains of bacteria with a pronounced effect on seed germination and on seedling growth, isolated from root surfaces and rhizosphere soil of maize, were selected for a study on the formation of biologically active substances. β-Indole acetic acid (45–72 μg/1.000 ml) was produced by four strains, gibberelline-like substances (1.0–60.0 μg/1.000ml) by all strains, biotin and pantothenic acid by the majority of strains and nicotinic acid by five strains. Amino acids were formed by all strains but in low amounts. Four strains produced growth inhibitors. The highest amounts of biologically active substances were found in cultures ofPseudomonas fluorescens andBacillus brevis. The various cultures ofPseudomonas fluorescens differed in their capability to produce biologically active substances. The majority of bacterial cultures or their supernatants significantly stimulated the germination of seeds and some of them significantly affected the growth of plants. Inoculation of maize seeds with strainsPseudomonas fluorescens andChromobacterium violaceum significantly increased the yield of dry matter of plants.
TL;DR: It is demonstrated that 82 per cent of pharyngeal cultures from normal individuals contain bacterial species which inhibit the growth of stock strains of pneumococci, and that only 2 of 12 tested contained inhibitors of the carrier pneumococcus.
TL;DR: In vitro incubations showed that sulphuric acid esters of the 3a, 38, 178, 178and 21-hydroxyl groups were all hydrolyzed by the caecal bacteria, showing that microbial hydrolysis of steroid sulphates takes place also in vivo.
Abstract: Caecal contents from conventional rats has been shown to have steroid sulphatase and glucuronidase activities. Whereas the sulphatase activity was of microbial origin the glucuronidase activity was also present in caecal contents from germfree rats. In vitro incubations showed that sulphuric acid esters of the 3a-, 38-, 178and 21-hydroxyl groups were all hydrolyzed by the caecal bacteria. The ratio between free and conjugated metabolites of [4-14C]corticosterone administered to germfree and conventional rats was much higher in the conventional than in the germfree rats. This shows that microbial hydrolysis of steroid sulphates takes place also in vivo.
TL;DR: The data are interpretated as suggesting that NAL altered the structure of DNA or a protein attached to nascent DNA and that this lesion can be partially repaired by DNA polymerase.
Abstract: Nalidixic acid (NAL) is bactericidal for E. coli B. Synthesis of deoxyribonucleic acid (DNA), ribonucleic acid and protein was necessary to initiate the lethal effect, but only protein synthesis was necessary to sustain it. NAL inhibited DNA synthesis specifically, but this inhibition occurred even under conditions that were not lethal to the bacteria. In contrast to other inhibitors of DNA synthesis, NAL did not cause the solubilization of cellular DNA even when bacteria were exposed to it for 2 hr. A bacterial mutant deficient in DNA polymerase was much more sensitive to the lethal action of NAL than its parent strain. Moreover, inhibition of protein synthesis did not protect this mutant from NAL-induced killing. NAL inhibited neither DNA polymerase, nor thymidine or thymidylate kinases. The data are interpretated as suggesting that NAL altered the structure of DNA or a protein attached to nascent DNA and that this lesion can be partially repaired by DNA polymerase.
TL;DR: Although lagoon pH was favorable for purple sulfur bacterial growth, temperatures and sulfides were not optimal in the lagoon for these organisms, and the increase of algae in the late summer of 1967 may have been related to the low organic content of the lagoons during this period.
Abstract: The ecology of purple sulfur bacteria in a sewage oxidation lagoon was investigated. Chemical changes in the lagoon were investigated by monitoring biochemical oxygen demand (BOD5), sulfide, sulfate, phosphate, total carbohydrates, volatile acids, alkalinity, and pH. Lagoon water temperatures were observed daily. Microbial ecological relationships were deduced by enumerating coliforms, total bacteria other than anaerobes [Tryptone Glucose Extract (TGE) agar], methane formers such as Methanobacterium formicicum, sulfate reducers, purple sulfur bacteria, and algae. Finally, two strains of purple sulfur bacteria were characterized. Two populations, purple sulfur bacteria and total bacteria (TGE agar), reached maximal concentrations in the warmest part of the 1967 summer. Purple sulfur bacteria reached maximal numbers as concentrations of sulfide and volatile acids were depleted, whereas carbohydrates and alkalinity remained unchanged. Low sulfate levels, which were not limiting for sulfate reducers, may be attributable to storage of sulfur within purple sulfur bacteria. No biological, chemical, or physical agent was linked to the removal of coliforms. The increase of algae in the late summer of 1967 may have been related to the low organic content of the lagoon during this period. Although lagoon pH (7.7 to 8.2) was favorable for purple sulfur bacterial growth, temperatures and sulfides were not optimal in the lagoon for these organisms. Chromatium vinosum and Thiocapsa floridana (the predominant lagoon purple sulfur organism in 1967 and 1968) utilized certain carbohydrates, amino acids, volatile acids, and Krebs cycle intermediates. Also purple sulfur bacteria lowered BOD levels as demonstrated by the growth of T. floridana in sterilized sewage.
Patent•
21 Oct 1970
TL;DR: In this article, the authors define and measure the presence, type, ANTIBOTIC SENSITIVITY and other MICRO-ORGANISMS PRESENT in any SELECTED SAMPLE SEVERAL TYPES OF GROWTH and CONDUCTIVITY CELLs are provided.
Abstract: MICROBIOLOGICAL GROWTH IS DETERMINED WITH GREAT RAPIDITY BY MEASURING ELECTRICAL CONDUCTIVITY CHANGES IN SEALED CELL HAVING SELECTED VARIETIES OF NUTRIENT MEDIA INOCULATED WITH A SAMPLE CONTAINING SUSPECTED MICROBIAL CONTAMINATION. THE MEASUREMENT AND SELECTION OF NUTRIENT MEDIA ALLOWS DETERMINATION OF THE PRESENCE, TYPE, ANTIBOTIC SENSITIVITY AND A QUANTITATIVE COUNT OF BACTERIA AND OTHER MICRO-ORGANISMS PRESENT IN ANY SELECTED SAMPLE SEVERAL TYPES OF GROWTH AND CONDUCTIVITY CELLS ARE PROVIDED FOR MEASURING THE CHANGE IN ELECTRICAL CONDUCTIVITY. D R A W I N G
TL;DR: A survey of the walls of over 80 bacterial species has been carried out using chromatographic and colorimetric techniques to demonstrate the presence of 2-keto-3-deoxy-octonic acid (KDO) and or sialic acid.
Abstract: SUMMARY: A survey of the walls of over 80 bacterial species has been carried out using chromatographic and colorimetric techniques to demonstrate the presence of 2-keto-3-deoxy-octonic acid (KDO) and or sialic acid. In most Gram-negative bacteria KDO but not sialic acid was found in the wall, whereas the walls of Gram-positive bacteria contained neither compound.
TL;DR: A group of eight new long-chain aliphatic compounds recently isolated from the avocado and some derivatives thereof were tested for antibacterial activity on 13 different species of bacteria and a yeast, and 1,2,4-Trihydroxy-n-hepadeca-16-en was found to be the most active.
Abstract: A group of eight new long-chain aliphatic compounds recently isolated from the avocado and some derivatives thereof were tested for antibacterial activity on 13 different species of bacteria and a yeast. Some of these compounds inhibited the growth of microorganisms. 1,2,4-Trihydroxy-n-hepadeca-16-en was found to be the most active, inhibiting certain gram-positive bacteria at 4 μg/ml.
TL;DR: The lactic acid group of bacteria occur on plants with some degree of constancy, but not of consistency, and seldom at high levels of population.
Abstract: The lactic acid group of bacteria occur on plants with some degree of constancy, but not of consistency, and seldom at high levels of population. Their role on the surfaces of plants is unknown, and apparently passive, for no functional, concrete role in an intimate bacterium to plant relationship has been detected.
TL;DR: Growth of salmonellae during the early stages of ripening and subsequent extended survival of these organisms may, in part, be attributable to the Most Probable Number technique.
Abstract: Cheddar cheese was made by the stirred-curd procedure from pasteurized milk inoculated with Salmonellea typhimurium and with a slow acid-producing strain of Streptococcus lactis. The Most Probable Number technique was used to enumerate salmonellae in milk and in cheese during its manufacture and ripening. Salmonellae grew rapidly during manufacture and limited additional growth occurred in cheese during the first week of ripening at 13 C after which there was a gradual decline in population. Salmonellae survived during ripening for up to approximately 7 months at 13 C and 10 months at 7 C. Cheese made in 2 of 5 trials exhibited a limited increase in number of salmonellae during the first 2 weeks at 7 C followed by a decline in population of these bacteria. Other cheeses held at 7 C exhibited a reduction in number of viable salmonellae without the initial increase. Growth of salmonellae during the early stages of ripening and subsequent extended survival of these organisms may, in part, be attributable to ...
TL;DR: It is found that this is a general phenomenon, resulting from the release of nucleic acids into plant cells, in shoots dipped in a suspension of Agrobacterium tumefaciens (strain B6), virulent to plants.
Abstract: BACTERIAL RNA has been recovered from the cells of shoots dipped in a suspension of Agrobacterium tumefaciens (strain B6), virulent to plants1. We have now found that this is a general phenomenon, resulting from the release of nucleic acids into plant cells.
Patent•
31 Aug 1970
TL;DR: In this paper, a LACBACTERIA CULTURE CULTURES EACH COMPRISES A LACTIC ACID BACTERia CULTURED in a NUTRIENT MEDIUML, and ACETYLATED MONOGLYCERIDE COATING on SAID CULTured BACBERIA, and a CARRIER BLENDED with COATED BAC TERIA, SAID CARRIERS SELECTED FROM A GROUP CONSISTING OF GLUCOSE, MODIFIED CELLULOSE, and MODIFIED STAR
Abstract: LACTIC ACID BACTERIA CULTURES EACH COMPRISES A LACTIC ACID BACTERIA CULTURED IN A NUTRIENT MEDIUML, AND ACETYLATED MONOGLYCERIDE COATING ON SAID CULTURED BACTERIA, AND A CARRIER BLENDED WITH COATED BACTERIA, SAID CARRIER SELECTED FROM A GROUP CONSISTING OF GLUCOSE, MODIFIED CELLULOSE, AND MODIFIED STARCHES.
TL;DR: Temporal exclusion and breakdown of superinfecting virus deoxyribonucleic acid were measured after infection with T4 and T5 bacteriophages of normal strains of Escherichia coli and strains deficient in endonuclease-I.
Abstract: Summary
Temporal exclusion and breakdown of superinfecting virus deoxyribonucleic acid were measured after infection with T4 and T5 bacteriophages of normal strains of Escherichia coli and strains deficient in endonuclease-I. Bacteria deficient in endonuclease-I when infected with T4 phage excluded superinfecting T4 with little solubilization of the secondary DNA. With wild-type bacteria exclusion was accompanied by extensive superinfection breakdown, probably caused by the bacterial endonuclease-I. In bacteria infected by T5 phage, superinfecting T2 phages could be excluded even when deoxyribonucleic acid degradation was inhibited by maintaining a low [Mg2+] in the growth medium. In the presence of 0.01 m-magnesium ions, both wild-type bacteria and bacteria deficient in endonuclease-I infected with T5 phage produced extensive solubilization of the DNA of superinfecting T2 or T4 phages. A nuclease induced by T5 was probably partly responsible for the DNA breakdown which occurred in these conditions.