Inhibition of bacterial growth and malolactic fermentation in wine by bacteriophage

Bacteriophage present in wine can attack bacterial starter cultures and inhibit the malolactic fermentation. The possibility of starter culture failure due to phage attack was studied in a commercial dry red wine of pH 3·23, inoculated with a multiple strain starter culture. During two stages of malolactic fermentation, bacterial growth and malate degradation in the wine were inhibited. A phage capable of lysing isolates of Leuconostoc oenos was isolated from the wine. The isolated phage had an icosahedral head of 42–45 nm diameter and a flexible, regularly cross-striated tail 197–207 nm long with a small baseplate. The results confirm that phage can attack bacterial starter cultures in wine at low pH.     

Efficiency of phage protein synthesis in lambda-infected E. coli minicells

Phage lambda major head protein, the gene E product, has been identified among other phage proteins synthesized in lambda-infected Escherichia coli minicells, separated by SDS-acrylamide gel electrophoresis. On stained gels, the same protein has also been detected among total (bacterial and phage) proteins of lambda-infected minicells. The contribution of lambda proteins to the total protein content of lambda-infected minicells was found to be about 12% following 30 min lambda-infection. The inhibition of lambda early protein synthesis (shown by other authors in nucleate bacterial cells) practically does not occur in minicells; this may be the reason of the observed high efficiency of phage protein synthesis.     

Generation of Affinity-Tagged Fluoromycobacteriophages by Mixed Assembly of Phage Capsids

Addition of affinity tags to bacteriophage particles facilitates a variety of applications, including vaccine construction and diagnosis of bacterial infections. Addition of tags to phage capsids is desirable, as modification of the tails can lead to poor adsorption and loss of infectivity. Although tags can readily be included as fusions to head decoration proteins, many phages do not have decoration proteins as virion components. The addition of a small (10-amino-acid) Strep-tag II (STAG II) to the mycobacteriophage TM4 capsid subunit, gp9, was not tolerated as a genetically homogenous recombinant phage but could be incorporated into the head by growth of wild-type phage on a host expressing the capsid-STAG fusion. Particles with capsids composed of wild-type and STAG-tagged subunit mixtures could be grown to high titers, showed good infectivities, and could be used to isolate phage-bacterium complexes. Preparation of a STAG-labeled fluoromycobacteriophage enabled capture of bacterial complexes and identification of infected bacteria by fluorescence.     

Isolation and morphology of temperature Agrobacterium tumefaciens bacteriophage

Zimmerer, Robert P. (The Pennsylvania State University, University Park), Robert H. Hamilton, and Christine Pootjes. Isolation and morphology of temperate Agrobacterium tumefaciens bacteriophage. J. Bacteriol. 92:746-750. 1966.-Lysogeny was detected in 14 strains of Agrobacterium tumefaciens among 130 bacterial strains tested with strain B-6 used as the host. Partial lysis was observed with 13 additional bacterial strains. Morphological studies of five strains showed that the phage had similar features. A typical phage (Lv-1) had a polyhedralshaped head, approximately 71 by 63 mmu, and a tail, approximately 211 mmu by 9.5 mmu. The phage nucleic acid was found to be deoxyribonucleic acid. The bacteriophage have been designated L (for lysogenic) followed by the bacterial strain designation in lower case letters.     

Isolation of the Bacteriophage Lambda Receptor from Escherichia coli

A factor which inactivates the phage lambda can be extracted from Escherichia coli. This factor is a protein and is located in the outer membrane of the bacterial envelope. It is found in extracts of strains which are sensitive to phage lambda, but not in extracts of strains specifically resistant to this phage. We conclude that this factor is the lambda receptor, responsible for the specific adsorption of the phage lambda to E. coli cells. A partial purification of the lambda receptor is described. Inactivation of the phage by purified receptor is shown to be accompanied by the release of deoxyribonucleic acid from the phage.     

A viscosimetric study of thermally induced release of ds-DNA from Un phage

The thermally induced ejection of DNA from the head of the Un phage was studied by viscosimetry, pH was used as a variable external factor. The results obtained suggest that the infection of the bacterium by the phage occurs in the pH range 6-10 rather than in the acidic medium (pH 4-5) because the infection can take place only if the DNA is completely ejected from the phage head. It was shown that the ejection of DNA upon dilution of the initial concentration of the phage depends on the time required for the equilibrium of the phage suspension in the corresponding buffer solution to be established after which the measurements can be performed. In our experiments, this time interval was 24 h.     

Purification and characterization of xenorhabdicin, a phage tail-like bacteriocin, from the lysogenic strain F1 of Xenorhabdus nematophilus.

Xenorhabdicin, the phage tail-like bacteriocins of Xenorhabdus nematophilus, and phage head particles, elements produced together after mitomycin induction in X. nematophilus lysogenic strain F1 cultures, were separated by DEAE chromatography, examined by transmission electron microscopy, and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Electrophoresis of xenorhabdicin showed two major subunits of 43 and 20 kDa corresponding to the sheath and the inner core, respectively. At least five other minor subunits of 67, 54, 35, 28, and 16 kDa were also characterized. Electrophoresis of the phage head capsids showed a major 40-kDa subunit and two minor 50- and 34-kDa subunits. Bactericidal activity recorded against closely related bacterial species and spontaneously produced by X. nematophilus resides in the xenorhabdicin particles and is another antimicrobial barrier to save the symbiotic association.     

Role of the Host Cell in Bacteriophage Morphogenesis: Effects of a Bacterial Mutation on T4 Head Assembly

In certain bacterial mutants, called groE, T4 phage head assembly is blocked specifically, implying that the host plays a direct role in head assembly. The block occurs early in the assembly process at the level of action of T4 gene 31.     

Features of Membrane Receptors in Bacterial Multiplication Process and Necessary Conditions for Phage Infection of Bacteria

According to the obtained experimental results, the thermal shock (from 37 to 53 °C) not only stops the multiplication process of Escherichia coli bacteria, but also causes bacterial titer to decrease gradually. After this period lasting up to 1 hour, the bacterial cells continue to grow. A similar type of response was observed when bacteria were subjected to acid shock. Increasing acidity of media leads to decrease of bacterial growth process, and finally, their titer curve sharply falls over time. Also, interesting results were obtained about necessary conditions for infecting the bacteria by phages. Particularly, DNA injection from phages into bacterial cells requires most of corresponding bacterial membrane receptors to be occupied by phages. We suppose that this occurs due to autocrine phenomenon when the signaling molecules block the DNA ejection from phage particles. This effect lasts until a certain number of phage particles are attached to the membrane. After that, DNA injection from phage head into the cytoplasm takes place and the process of bacterial infection begins. The real number of phages in a stock is by several orders higher than the number of plaque-forming units in a given stock, which is determined by a classical double-layer agar method.     

THE RELATIONSHIP BETWEEN BACTERIAL GROWTH AND PHAGE PRODUCTION

1. The effects of temperature and H-ion concentration on the reaction between antistaphylococcus phage and a susceptible staphylococcus have been studied. 2. The temperature optimum for phage production is in the neighborhood of 35°C. and that for bacterial growth is approximately 40°C. 3. With increasing H-ion concentrations there occur: (a) an increase in the lag phase of bacterial growth without any corresponding increase in the lag phase of phage production; (b) a diminution in the total bacterial population accumulating in the medium without any corresponding drop in the total amount of phage formed. 4. With increasing alkalinity there is no pronounced change in the curves of bacterial growth and phage formation. At pH 8.5 the lytic threshold is increased to about 1000 phage units per bacterium instead of 100–140 as is usually the case and the time of lysis is delayed. 5. By adjusting the medium to pH 6 and 28°C. bacterial growth can be completely inhibited while phage production continues at a rapid rate. 6. Apparently, the previously stressed importance of bacterial growth as the prime conditioning factor for phage formation does not hold, for under certain experimental conditions the two mechanisms can be dissociated.     

Host participation in bacteriophage lambda head assembly

Mutants of Escherichia coli, called groE, specifically block assembly of bacteriophage λ heads. When groE bacteria are infected by wild type λ, phage adsorption, DNA injection and replication, tail assembly, and cell lysis are all normal. No active heads are formed, however, and head related “monsters” are seen in lysates. These monsters are similar to the structures seen on infection of wild-type cells by phage defective in genes B or C.We have isolated mutants of λ which can overcome the block in groE hosts and have mapped these mutants. All groE mutations can be compensated for by mutation of phage gene E (hence the name groE). Gene E codes for the major structural subunit of the phage head. Some groE mutants, called groEB, can be compensated by mutation in either gene E or in gene B. Gene B is another head gene.During normal head assembly the protein encoded by phage head gene B or C appears to be converted to a lower molecular weight form, h3, which is found in phage. The appearance of h3 protein in fast sedimenting head related structures requires the host groE function.We suggest that the proteins encoded by phage genes E, B and C, and the bacterial component defined by groE mutations act together at an early stage in head assembly.     

A bacteriophage of a moderately halophilic bacterium

A bacteriophage of an aerobic, gram-negative, rod-shaped halophilic bacterium, provisionally named Pseudomonas sp. G3, is described. The phage has a head and a tail and is similar in appearance to Salmonella phage Beccles. It infects its bacterial host at all salt concentrations in which the bacteirum is able to grow. In contrast to phages of halophilic archaebacteria, the newly-described phage is relatively stable in the absence of salt. It also infects Vibrio costicola and two unidentified halophilic eubacteria.Abbreviations PPT proteose peptone-tryptone medium - pfu plaque-forming unit - G+C guanine + cytidine content, mol %     

THE EFFECT OF NaCl ON THE PHAGE-BACTERIUM REACTION

1. The presence of 0.25 M NaCl during the reaction between a staphylococcus phage and susceptible organisms results in a five to tenfold increase in the amount of phage produced. 2. Analysis of the reaction indicates that normal kinetic relationships exist until just before lysis occurs. At this time the organisms enter the stationary phase, lysis is delayed approximately 0.7 hour as compared with control mixtures and phage continues to be produced at the usual rapid rate. 3. Apparently there are conditions under which phage can be produced in the absence of bacterial growth although previous work has uniformly emphasized growth of the bacterial substrate as the prime conditioning factor for formation of phage.     

Specialized transduction of the biotin region of Escherichia coli by phage T1.

Summary Phage T1 transduces Bio⁺ by special mechanism which leads to a higher efficiency of Bio⁺ transduction than other bacterial markers. Efficient Bio⁺ transduction depends on a site located between the galactose operon and the bacterial attachment site for phage . Evidence is presented which supports the hypothesis that the site is essential for efficient Bio⁺ transduction because at the site phage T1 initiates head filling in a polar (unidirectional) fashion leading to increased pickup of the Bio⁺ marker.     

Isolation and characteristics of mutation pfm affecting the penetration of phage Mu into Escherichia coli K-12 cells

A mutant of Escherichia coli K-12 strain with the destroyed process of establishment of lysogenic state for phage Mu in the course of zygotic induction has been obtained. The mutation revealed, designated pfm (penetration factor for Mu), interferes with adsorption of phage Mu to the surface of E. coli K-12 cells. On the basis of data obtained, there is every reason to believe that the phage Mu DNA connection with the membrane components of the bacterial cell provides optimizing condition for the primary integrative transposition of phage Mu at the stage of Mu DNA introduction into the cell.     

Novel Phage Group Infecting Lactobacillus delbrueckii subsp. lactis,as Revealed by Genomic and Proteomic Analysis of Bacteriophage Ldl1

Ldl1 is a virulent phage infecting the dairy starter Lactobacillus delbrueckii subsp. lactis LdlS. Electron microscopy analysis revealed that this phage exhibits a large head and a long tail and bears little resemblance to other characterized phages infecting Lactobacillus delbrueckii. In vitro propagation of this phage revealed a latent period of 30 to 40 min and a burst size of 59.9 ± 1.9 phage particles. Comparative genomic and proteomic analyses showed remarkable similarity between the genome of Ldl1 and that of Lactobacillus plantarum phage ATCC 8014-B2. The genomic and proteomic characteristics of Ldl1 demonstrate that this phage does not belong to any of the four previously recognized L. delbrueckii phage groups, necessitating the creation of a new group, called group e, thus adding to the knowledge on the diversity of phages targeting strains of this industrially important lactic acid bacterial species.     

Identification of gene products required for in vitro formation of the internal peptides of bacteriophage T4.

In vitro formation of both bacteriophage T4 internal peptides (II and VII) from preexisting precursor protein was shown to require the product of T4 gene 21. The proteolytic factor was detectable in extracts of cells infected with certain phage mutants blocked in early steps of head assembly but could not be demonstrated in extracts of T4 wild-type infected cells. This finding suggests that the proteolytic factor is inactivated during normal phage assembly. The product of T4 gene 22 appears to be the precursor of peptide VII but not of peptide II.     

Electron-microscopic study of the serological affinity between the antigenic components of phages T4 and DDVI.

In an investigation of the antigenic fine structure of phages T4 and DDVI with the use of the neutralization reaction and electron-microscopic observation of the phage-antibody complexes, it has been possible to establish that the head of phage T4 consists of proteins which have antigenic determinants of two types: The first type is identical to the antigens of the head of phage DDVI, and the second type is apparently absent in phage DDVI. The phage DDVI head contains mostly determinants which are common to the phage T4 head, since it was not possible to detect antigenically specific components in the phage DDVI head. The tail sheaths of phage T4 and DDVI appear to be identical in the antigenic respect. A difference has been observed in the fibers and the base plates of the phages investigated. The presence of the following three types of antigens has been established: 1) common to phages T2, T4, and DDVI, 2) common to phages T4 and DDVI, and 3) specific for each phage investigated.     

The phage-host arms race: shaping the evolution of microbes

Bacteria, the most abundant organisms on the planet, are outnumbered by a factor of 10 to 1 by phages that infect them. Faced with the rapid evolution and turnover of phage particles, bacteria have evolved various mechanisms to evade phage infection and killing, leading to an evolutionary arms race. The extensive co-evolution of both phage and host has resulted in considerable diversity on the part of both bacterial and phage defensive and offensive strategies. Here, we discuss the unique and common features of phage resistance mechanisms and their role in global biodiversity. The commonalities between defense mechanisms suggest avenues for the discovery of novel forms of these mechanisms based on their evolutionary traits.