Induction and partial purification of bacteriophages from Desulfovibrio vulgaris (Hildenborough) and Desulfovibrio desulfuricans ATCC 13541.

Bacteriophages were induced from cultures of Desulfovibrio vulgaris NCIMB 8303 and Desulfovibrio desulfuricans ATCC 13541 by UV light. The optimum time of UV exposure was 1 min and the maximum yield of phage was obtained 9-10 h after UV treatment. The two phage preparations were compared by restriction enzyme analysis and Southern blot hybridization. The nucleic acid from both phages was cut by restriction endonucleases specific for double-stranded DNA. The phage DNAs from D. vulgaris and D. desulfuricans showed different restriction enzyme cleavage patterns. No homology was observed between a 25 kb probe from the D. vulgaris phage DNA and the phage DNA from D. desulfuricans. Protein profiles of the phages from both sources were also studied; the D. vulgaris phage contained two major bands corresponding to Mr values of 37 000 and 56 000 while the D. desulfuricans phage contained only one major band, of Mr 38 000.     

Characterization of three Lactobacillus delbrueckii subsp. bulgaricus phages and the physicochemical analysis of phage adsorption

AIMS: Three indigenous Lactobacillus delbrueckii subsp. bulgaricus bacteriophages and their adsorption process were characterized. METHODS AND RESULTS: Phages belonged to Bradley's group B or the Siphoviridae family (morphotype B1). They showed low burst size and short latent periods. A remarkably high sensitivity to pH was also demonstrated. Indigenous phage genomes were linear and double-stranded DNA molecules of approx. 31-34 kbp, with distinctive restriction patterns. Only one phage genome appeared to contain cohesive ends. Calcium ions did not influence phage adsorption, but it was necessary to accelerate cell lysis and improve plaque formation. The adsorption kinetics were similar on viable and nonviable cells, and the adsorption rates were high between 0 and 50 degrees C. SDS and proteinase K treatments did not influence the phage adsorption but mutanolysin and TCA reduced it appreciably. No significant inhibitory effect on phage adsorption was observed for the saccharides tested. This study also revealed the irreversibility of phage adsorption to their hosts. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The study increases the knowledge on phages of thermophilic lactic acid bacteria.     

Characterization of two inducible bacteriophages, alpha 1 and alpha 2, isolated from Clostridium botulinum type A 190L and their deoxyribonucleic acids

Two inducible bacteriophages, alpha 1 and alpha 2, isolated from Clostridium botulinum type A strain 190L and their deoxyribonucleic acids (DNAs) were purified and characterized. Phage alpha 1, which is unable to form plaques on any strain of C. botulinum, was produced in large quantities after treatment with mitomycin C (MC), whereas phage alpha 2, which was induced in much lower quantities than phage alpha 1, propagated in cultures of type A strain Hall. The phage DNAs were exclusively synthesized after induction with MC. Alpha 1 and alpha 2 DNAs had sedimentation coefficients of 34.0 and 30.6 S, corresponding to molecular weights of 31.9 x 10(6) and 23.5 x 10(6), respectively. The buoyant density in CsC1 was 1.682 g/cm3 for alpha 1 DNA and 1.680 g/cm3 for alpha 2 DNA. Based on thermal denaturation characteristics, the genomes of both phages were shown to be double-stranded DNAs. Agarose gel electrophoretic profiles of the phage DNAs digested with restriction endonuclease EcoRI revealed nine fragments for alpha 1 DNA and six fragments for alpha 2 DNA. The molecular weights of the phage DNAs as determined by restriction enzyme analysis were 30.55 x 10(6) for alpha 1 DNA and 25.83 x 10(6) for alpha 2 DNA. Nontoxigenic mutants obtained from strain 190L could, like the toxigenic parent strain, produce the two phages after treatment with MC. Lysogenic conversion to toxigenicity by phage alpha 2 was not observed with the nontoxigenic mutants. It seems likely that there is no relationship between either phage genome and the toxigenicity of C. botulinum type A.     

小单孢菌40027菌株噬菌体的分离及其生物学特性的研究

以福堤霉素A产生菌──小单孢菌40027菌株为指示菌,从土壤中分离得到三株噬菌体:ΦHAU7、ΦHAU9和ΦHAU11。三株噬菌体的寄主专一性较强,在测试的15株放线菌菌株中,三株噬菌体能感染小单孢菌40027菌株和A-M-01菌株,ΦHAU9和ΦHAU11还能感染蔷薇小单孢菌(Micromonospora purprea)。三株噬菌体都是由多面体的头部和尾部组成;形成噬菌斑时培养基中适宜的Ca2 、Mg2 浓度分别为32mM和30mM;ΦHAU7在储存液中适宜的pH范围为6~12,而其它两株噬菌体的适宜的pH范围为6~10;在储存过程中三株噬菌体适宜的温度范围为28~37℃,经60℃保温30min后,除ΦHAU7仍有53%活力之外,其它两株噬菌体全部失活。限制性内切酶酶切结果表明:三株噬菌体基因组DNA均为双链DNA;基因组大小分别约为60kb、58kb和55kb。高压脉冲电泳结果揭示:三株噬菌体基因组DNA均具有粘性末端。     

BspLS2I--a new site-specific endonuclease from the thermophilic bacteria Bacillus species LS2]

A new restriction endonuclease BspLS2I was isolated from the thermophilic bacterium Bacillus species LS2 and purified by blue sepharose and hydroxyapatite chromatographies. The enzyme is an isoschizomer of SduI from Streptococcus durans. BspLS2I recognizes the sequence 5' G(G/A/T)GC(C/T/A) decreases C 3' on double-stranded DNA and cleaves it is indicated by the arrow to yield sticky-ended DNA fragments. Maximum catalytic activity of endonuclease was found in 10 mM tris-HCl (pH 7.9) in the presence of 15-30 mM MgCl2 at 50 degrees C. The phage T4 glucosylated DNA is not cleaved by the enzyme.     

Restriction and modification in B. subtilis: the role of homology between donor and recipient DNA in transformation and transfection

Non-modified DNAs from phages SPO2 and phi 105, and prophage DNAs extracted from lysogens carrying these phages, were used to transfect isogenic r+m+ B. subtilis recipients which were either non-lysogenic, or had been lysogenized with a homologous or a non-homologous phage. Restriction of transfecting phage and prophage DNA occurred in non-lysogenic recipients and in recipients lysogenic for a non-homologous phage. No effect of restriction was observed when phage or prophage DNA was used to transfect recipients carrying a homologous prophage. This is analogous to the absence of restriction in transformation and indicates that in B. subtilis the distinction between transforming and transforming and transfecting DNA is not made at the initial stages of DNA uptake and processing, but rather at later stages, where recognition of homologous regions in donor and recipient DNA plays an important role.     

DNA polymerase from Sulfolobus acidocaldarius. Replication at high temperature of long stretches of single-stranded DNA

The activity of a homogeneous DNA polymerase from the thermophilic archaebacterium, Sulfolobus acidocaldarius, on a singly primed, single-stranded recombinant phage M13 DNA has been examined. At the optimal temperature (70 to 75 degrees C) this template is efficiently replicated in ten minutes using a ratio of enzyme molecule to primed-template of 0.8. Analysis of DNA products during the course of polymerization shows that species of quite homogeneous size are observed and that the number of primers extended by the enzyme is constant, whatever the enzyme molecule to primed template ratio is in the range 1/50 to 2, indicating that the 100 x 10(3) Mr DNA polymerase from S. acidocaldarius is randomly recycled on the template molecules. At non-optimal temperature (60 degrees C and 80 degrees C) the distribution of products observed indicated the presence of arrest sequences; some have been shown to be reversible. One of these pausing signals detected at 80 degrees C has been further analysed, and has been found to be DNA sequence-dependent.     

Inactivation of bacteriophages by decay of incorporated radioactive phosphorus

The inactivation of the phages T1, T2, T3, T5, T7, and lambda by decay of incorporated P(32) has been studied. It was found that these phages fall into two classes of sensitivity to P(32) decay: at the same specific activity of P(32) in their deoxyribonucleic acid (DNA), T2 and T5 are inactivated three times as rapidly as T1, T3, T7, and lambda. Since the strains of the first class were found to contain about three times as much total phosphorus per phage particle as those of the second) it appears that the fraction of all P(32) disintegrations which are lethal is very nearly the same in all the strains. This fraction alpha depends on the temperature at which decay is allowed to proceed, being 0.05 at -196 degrees C., 0.1 at +4 degrees C., and 0.3 at 65 degrees C. Decay of P(32) taking place only after the penetration of the DNA of a radioactive phage particle into the interior of the bacterial cell can still prevent the reproduction of the parental phage, albeit inactivation now proceeds at a slightly reduced rate. T2 phages inactivated by decay of P(32) can be cross-reactivated; i.e., donate some of their genetic characters to the progeny of a mixed infection with a non-radioactive phage. They do not, however, exhibit any multiplicity reactivation or photoreactivation. The fact that at low temperatures less than one-tenth of the P(32) disintegrations are lethal to the phage particle and the dependence of the fraction of lethal disintegrations on temperature can be accounted for by the double stranded structure of the DNA macromolecule.     

Characterization of bacteriophage nucleic acids obtained from Clostridium botulinum types C and D.

Nontoxigenic strains of Clostridium botulinum types C and D are converted to toxigenic strains by infection with specific Tox+ bacteriophages. The nucleic acids were extracted from five converting phages, c-st, c-468, c-203, c-d6f, and d-1873, and one nonconverting phage, c-n71, and treated with nucleases. The nucleic acids isolated were not digested by RNase A, but were digested by DNase I and exonuclease III, indicating that they were double-stranded DNA. On the basis of the restriction endonuclease digestion patterns on 0.8% agarose gel electrophoresis, the length of c-st, c-n71, c-468, and c-d6f phage DNAs was estimated to be about 110 kilobase pairs and that of c-203 and d-1873 was about 150 kilobase pairs. The digestion patterns of c-st, c-468, and c-n71 phage DNAs by PstI and HindIII were very similar. High homology was observed in the dot hybridization test. For other phages and nucleases, a good similarity was not observed. Only a little similarity was observed between c-203 and c-d6f phages. The existence of the structural genes for the toxin in both c-st and c-n71 phages was confirmed by the hybridization test with these phage DNAs and the oligonucleotide probe which represented the DNA sequence predicted for the N-terminal amino acids (2 to 17) of C. botulinum type C toxin. The loss of the converting ability of c-n71 phage may be caused not by the deletion of the tox+ gene but rather by the base mutation in c-st phage DNA.     

Characterization of bacteriophage nucleic acids obtained from Clostridium botulinum types C and D

Nontoxigenic strains of Clostridium botulinum types C and D are converted to toxigenic strains by infection with specific Tox+ bacteriophages. The nucleic acids were extracted from five converting phages, c-st, c-468, c-203, c-d6f, and d-1873, and one nonconverting phage, c-n71, and treated with nucleases. The nucleic acids isolated were not digested by RNase A, but were digested by DNase I and exonuclease III, indicating that they were double-stranded DNA. On the basis of the restriction endonuclease digestion patterns on 0.8% agarose gel electrophoresis, the length of c-st, c-n71, c-468, and c-d6f phage DNAs was estimated to be about 110 kilobase pairs and that of c-203 and d-1873 was about 150 kilobase pairs. The digestion patterns of c-st, c-468, and c-n71 phage DNAs by PstI and HindIII were very similar. High homology was observed in the dot hybridization test. For other phages and nucleases, a good similarity was not observed. Only a little similarity was observed between c-203 and c-d6f phages. The existence of the structural genes for the toxin in both c-st and c-n71 phages was confirmed by the hybridization test with these phage DNAs and the oligonucleotide probe which represented the DNA sequence predicted for the N-terminal amino acids (2 to 17) of C. botulinum type C toxin. The loss of the converting ability of c-n71 phage may be caused not by the deletion of the tox+ gene but rather by the base mutation in c-st phage DNA.     

Molecular characterization of a second abortive phage resistance gene present in Lactococcus lactis subsp. lactis ME2.

The fifth phage resistance factor from the prototype phage-insensitive strain Lactococcus lactis subsp. lactis ME2 has been characterized and sequenced. The genetic determinant for Prf (phage resistance five) was subcloned from the conjugative plasmid pTN20, which also encodes a restriction and modification system. Typical of other abortive resistance mechanisms, Prf reduces the efficiency of plaquing to 10(-2) to 10(-3) and decreases the plaque size and burst size of the small isometric-headed phage p2 in L. lactis subsp. lactis LM0230. However, normal-size plaques occurred at a frequency of 10(-4) and contained mutant phages that were resistant to Prf, even after repeated propagation through a sensitive host. Prf does not prevent phage adsorption or promote restriction and modification activities, but 90% of Prf+ cells infected with phage p2 die. Thus, phage infections in Prf+ cells are aborted. Prf is effective in both L. lactis subsp. lactis and L. lactis subsp. cremoris strains against several small isometric-headed phages but not against prolate-headed phages. The Prf determinant was localized by Tn5 mutagenesis and subcloning. DNA sequencing identified a 1,056-nucleotide structural gene designated abiC. Prf+ expression was obtained when abiC was subcloned into the lactococcal expression vector pMG36e. abiC is distinct from two other lactococcal abortive phage resistance genes, abiA (Hsp+, from L. lactis subsp. lactis ME2) and abi416 (Abi+, from L. lactis subsp. lactis IL416). Unlike abiA, the action of abiC does not appear to affect DNA replication. Thus, abiC represents a second abortive system found in ME2 that acts at a different point of the phage lytic cycle.     

8株动物源编码Stx2短尾噬菌体的生物学特性

[目的]对8株源自大肠杆菌O157编码Stx2毒素的噬菌体生物学特性进行研究.[方法]丝裂霉素C诱导8株大肠杆菌O157菌株释放噬菌体,采用PCR作初步鉴定,分离、纯化噬菌体基因组,随机引物法地高辛(DIG)标记stx2基因片段作为探针,对纯化的噬菌体采用Southernblot进行Stx2噬菌体再次鉴定,透射电子显微镜观察纯化的8株Stx2噬菌体的形态特征,通过限制性内切酶图谱分析,确定噬菌体的核酸类型和基因组大小、以及限制性内切酶酶切片段多态性,并分析噬菌体的蛋白质组成特征.[结果]Southern blot证实分离的8株噬菌体为Stx2噬菌体,电镜下观察的各株Stx2噬菌体形态一致,头部均为正六边形,尾部很短,属于短尾噬菌体科,各株噬菌体之间存在相同的蛋白结构模式,基因组为双链DNA,限制性内切酶片段长度表现出一定的多态性,噬菌体的基因组大小从48.0-65.3 kb不等.[结论]来源不同菌株的8株编码Stx2噬菌体均为短尾噬菌体,其蛋白结构模式一致,但基因组具有不同组成.     

DNA relatedness among bacteriophages of the morphological group C3

Six bacteriophages with an elongated head and a short, noncontractile tail were compared by DNA-DNA hybridization, seroneutralization kinetics, mol% G+C and molecular weight of DNA, and host range. Three phage species could be identified. Phage species 1 containedEnterobacter sakazakii phage C2,Erwinia herbicola phages E3 and E16P, andSalmonella newport phage 7–11. These phages had a rather wide host range (4 to 13 bacterial species). DNA relatedness among species 1 phages was above 75% relative binding ratio (S1 nuclease method, 60°C) when labeled DNA from phage C2 was used, and above 41% when labeled DNA from phage E3 was used. Molecular weight of DNA was about 58×10⁶ (C2) to 67 ×10⁶ (E3). The mol% G+C of DNA was 43–45. Anti-C2 serum that neutralizes all phages of species 1 does not neutralize phages of the other two species. Species 2 contains only coliphage Esc-7-11, whose host range was only oneEscherichia coli strain out of 188 strains of Enterobacteriaceae studied; it was unrelated to the other two species by seroneutralization and DNA hybridization. DNA from phage Esc-7-11 had a base composition of 43 mol% G+C and a molecular weight of about 45×10⁶. Species 3 contains onlyProteus mirabilis phage 13/3a. Its host range was limited to swarmingProteus species. Species 3 was unrelated to the other two species by seroneutralization and DNA hybridization. DNA from phage 13/3a had a base composition of 35 mol% G+C and molecular weight of about 53×10⁶. It is proposed that phage species be defined as phage nucleic acid hybridization groups.     

Estimation of ruminal bacteriophage numbers by pulsed-field gel electrophoresis and laser densitometry.

To investigate phage activity in the rumen, a method for quantifying phage has been developed. By differential centrifugation and ultrafiltration, phage particles were separated and concentrated from ruminal fluid. Linear double-stranded DNA from this fraction containing predominantly tailed phage was isolated and separated by size, using pulsed-field gel electrophoresis (PFGE). Laser densitometry of gel photographs allowed the numbers of phages with DNA in each size region to be calculated and, therefore, the total numbers per milliliter of ruminal fluid to be estimated. Phage numbers were estimated to be between 3 x 10(9) and 1.6 x 10(10) particles ml of ruminal fluid-1. The phage population, as gauged by the appearance of DNA on PFGE gels, had two major components. A broad region of DNA between 30 and 200 kb was always present on PFGE gels. It appears this region comprises DNA from a great many different phages and would include most of the temperate phages. In addition, discrete DNA bands ranging in size from 10 to 850 kb were frequently observed. DNA from one such band, of 12 kb in size, was shown to consist primarily of a single DNA type, suggesting that it originated from a specific phage. It is postulated that the discrete bands are due to epidemics or blooms of phage activity from specific, probably lytic, phages. The method that has been developed will greatly enhance future investigations into the interactions between the ruminal phage population, the ruminal bacterial population, and animal nutrition and growth.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of bacteriophages for Micromonospora purpurea.

Chemical and physical stabilities of bacteriophages ?UW 21 and ?UW 51 infecting Micromonospora purpurea ATCC 15835 were examined. Both phages were stable over the pH range of 5 to 8 and to heating at temperatures up to 50 degrees C and especially stable in buffer containing magnesium ion. Exposure to 1 M Ca(NO3)2 inactivated both phages, and phage ?UW 51 was also susceptible to 1 M CaCl2, 0.1 M tris(hydroxymethyl)aminomethane, and 0.3% H2O2. Phage plating efficiency was highest on the cultures at logarithmic phase and sometimes much influenced by host growth. Phage ?UW 51 has a latent period of 2 h at 34 degrees C and a burst size between 35 and 40. The latent period for phage ?UW 21 is about 12 h, and the burst size is smaller than 30.     

Restriction of bacteriophage plaque formation in Streptomyces spp.

Several Streptomyces species that produce restriction endonucleases were characterized for their ability to propagate 10 different broad host range bacteriophages. Each species displayed a different pattern of plaque formation. A restrictionless mutant of S. albus G allowed plaque formation by all 10 phages, whereas the wild-type strain showed plaques with only 2 phages. DNA isolated from three of the phages was analyzed for the presence of restriction sites for Streptomyces species-encoded enzymes, and a very strong correlation was established between the failure to form plaques on Streptomyces species that produced particular restriction enzymes and the presence of the corresponding restriction sites in the phage DNA. Also, the phages that lacked restriction sites in their DNA generally formed plaques on the corresponding restriction endonuclease-producing hosts at high efficiency. The DNAs from the three phages analyzed also generally contained either many or no restriction sites for the Streptomyces species-produced enzymes, suggesting a strong evolutionary trend to either eliminate all or tolerate many restriction sites. The data indicate that restriction plays a major role in host range determination for Streptomyces phages. Analysis of bacteriophage host ranges of many other uncharacterized Streptomyces hosts has identified four relatively nonrestricting hosts, at least two of which may be suitable hosts for gene cloning. The data also suggest that several restriction systems remain to be identified in the genus Streptomyces.     

Transduction of penicillinase production and other antibiotic-resistance markers in Staphylococcus epidermidis.

Transduction of resistance from a multiply antibiotic-resistant strain of Staphylococcus epidermidis sub-group II was studied using the typing phage 108. The effect of increasing doses of ultraviolet radiation on the transducing phage was used to indicate the chromosomal or plasmid nature of the genes. Tetracycline and chloramphenicol resistance behaved as plasmid genes and streptomycin resistance as a chromosomal marker. It was also possible to transduce penicillin resistance (Pc) due to penicillinase production (bla+) using a low level of benzylpenicillin (0.03 microgram ml-1) for recovery. Approximately 10(-5) transductant colonies per phage input were obtained and ultraviolet kinetics indicated that Pc was plasmid carried. Pc transductants fell into two categories. In one group PC was stable as in the donor strain and transductants had the same phage sensitivity as the recipient. In the other, Pc was unstable at 37 degrees C and the instability was enhanced by growth at approximately 43.5 degrees C; these transductants also gained genes for restriction and modification of certain phages. Transductants that subsequently lost bla+ also lost the restriction and modification characters.     

Milk contamination and resistance to processing conditions determine the fate of Lactococcus lactis bacteriophages in dairies

Milk contamination by phages, the susceptibility of the phages to pasteurization, and the high levels of resistance to phage infection of starter strains condition the evolution dynamics of phage populations in dairy environments. Approximately 10% (83 of 900) of raw milk samples contained phages of the quasi-species c2 (72%), 936 (24%), and P335 (4%). However, 936 phages were isolated from 20 of 24 (85%) whey samples, while c2 was detected in only one (4%) of these samples. This switch may have been due to the higher susceptibility of c2 to pasteurization (936-like phages were found to be approximately 35 times more resistant than c2 strains to treatment of contaminated milk in a plate heat exchanger at 72 degrees C for 15 s). The restriction patterns of 936-like phages isolated from milk and whey were different, indicating that survival to pasteurization does not result in direct contamination of the dairy environment. The main alternative source of phages (commercial bacterial starters) does not appear to significantly contribute to phage contamination. Twenty-four strains isolated from nine starter formulations were generally resistant to phage infection, and very small progeny were generated upon induction of the lytic cycle of resident prophages. Thus, we postulate that a continuous supply of contaminated milk, followed by pasteurization, creates a factory environment rich in diverse 936 phage strains. This equilibrium would be broken if a particular starter strain turned out to be susceptible to infection by one of these 936-like phages, which, as a consequence, became prevalent.     

Staphylococcus aureus bacteriophages mediating the simultaneous lysogenic conversion of beta-lysin, staphylokinase and enterotoxin A: molecular mechanism of triple conversion

A new group of serotype F bacteriophages of Staphylococcus aureus has been found which mediates the simultaneous triple-lysogenic conversion of enterotoxin A, staphylokinase and beta-lysin. The phages were recovered fro methicillin-resistant strains of S. aureus isolated in Irish hospitals between 1971 and 1988 and from strain PS42-D, which has been used as the propagating strain for the S. aureus typing phage 42D since before 1965. The molecular mechanism of triple conversion mediated by three of these phages was determined by molecular cloning, restriction endonuclease site mapping and hybridization analysis, and compared with the mechanism of beta-lysin and staphylokinase conversion mediated by the serotype F, double-converting phase phi 13. THe genetic determinants mediating expression of enterotoxin A (entA) and staphylokinase (sak) were cloned from the DNA of the triple-converting phage and expression of the cloned determinants detected in Escherichia coli and S. aureus. The entA and sak determinants were closely linked in the phage DNA adjacent to the phage attachment site (attP) in each case and furthermore, the sak determinant of phage phi 13 was also located near its attP. The restriction maps of the entA-, sak- and attP-containing DNA regions of the three triple-converting phages were very similar to each other and to the corresponding sak- and attP- containing DNA region of phage phi 13. Hybridization analysis using a cloned beta-lysin determinant (hlb) and cloned attP-containing DNA fragments as probes demonstrated that beta-lysin conversion mediated by the triple-converting phages and phage phi 13 was caused by insertional inactivation of the chromosomally encoded hlb determinant by orientation-specific integration of phage DNA following lysogenization.     

Isolation and characterization of five Erwinia amylovora bacteriophages and assessment of phage resistance in strains of Erwinia amylovora

Phages able to infect the fire blight pathogen Erwinia amylovora were isolated from apple, pear, and raspberry tissues and from soil samples collected at sites displaying fire blight symptoms. Among a collection of 50 phage isolates, 5 distinct phages, including relatives of the previously described phages phiEa1 and phiEa7 and 3 novel phages named phiEa100, phiEa125, and phiEa116C, were identified based on differences in genome size and restriction fragment pattern. phiEa1, the phage distributed most widely, had an approximately 46-kb genome which exhibited some restriction site variability between isolates. Phages phiEa100, phiEa7, and phiEa125 each had genomes of approximately 35 kb and could be distinguished by their EcoRI restriction fragment patterns. phiEa116C contained an approximately 75-kb genome. phiEa1, phiEa7, phiEa100, phiEa125, and phiEa116C were able to infect 39, 36, 16, 20, and 40, respectively, of 40 E. amylovora strains isolated from apple orchards in Michigan and 8, 12, 10, 10, and 12, respectively, of 12 E. amylovora strains isolated from raspberry fields (Rubus spp.) in Michigan. Only 22 of 52 strains were sensitive to all five phages, and 23 strains exhibited resistance to more than one phage. phiEa116C was more effective than the other phages at lysing E. amylovora strain Ea110 in liquid culture, reducing the final titer of Ea110 by >95% when added at a ratio of 1 PFU per 10 CFU and by 58 to 90% at 1 PFU per 10(5) CFU.