1
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Sanders ME, Leonhard PJ, Sing WD, Klaenhammer TR. Conjugal strategy for construction of fast Acid-producing, bacteriophage-resistant lactic streptococci for use in dairy fermentations. Appl Environ Microbiol 2010; 52:1001-7. [PMID: 16347196 PMCID: PMC239164 DOI: 10.1128/aem.52.5.1001-1007.1986] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriophage-resistant dairy streptococci were obtained following conjugal transfer of pTR2030 from a lactose-negative donor, Streptococcus lactis TEK12, to lactose-positive recipient strains, Streptococcus cremoris LMA13 and 924 and S. lactis LMA12. Fast acid-producing, phage-resistant transconjugants were selected by challenge with homologous phage on fast-slow differential agar or lactose indicator agar. Acquisition of pTR2030 by the transconjugants was confirmed by DNA-DNA hybridization. Resistance of transconjugants to homologous phage was complete. Curing or deletion of pTR2030 in the transconjugants confirmed that phage resistance was due to pTR2030 acquisition and not to coincident background mutation. Phage-sensitive pTR2030 deletion derivatives of LMA12 transconjugants were isolated in vivo. The HindIII fragment B of pTR2030 was subcloned into pBR322 to yield a recombinant plasmid, pMET2, useful as a source of pTR2030 DNA. A specific, chemically synthesized oligomer useful as a pTR2030 probe was derived from the sequence of a small portion of pTR2030. The conjugal strategy presented here was effective in yielding fast acid-producing, phage-resistant S. cremoris and S. lactis strains without the use of antibiotic resistance markers and without interfering with the acid-producing ability of the recipient strain.
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Affiliation(s)
- M E Sanders
- Biotechnology Group, Marschall/Miles Laboratories, Elkhart, Indiana 46515, and Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695-7624
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2
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Murphy MC, Steele JL, Daly C, McKay LL. Concomitant conjugal transfer of reduced-bacteriophage-sensitivity mechanisms with lactose- and sucrose-fermenting ability in lactic streptococci. Appl Environ Microbiol 2010; 54:1951-6. [PMID: 16347707 PMCID: PMC202785 DOI: 10.1128/aem.54.8.1951-1956.1988] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ten previously reported lactose-positive (Lac) transconjugants from Streptococcus lactis, S. cremoris, and S. lactis subsp. diacetylactis and one sucrose-positive (Suc) transconjugant from S. lactis were examined for their sensitivity to prolate- and small isometric-headed bacteriophages. Four of the Lac transconjugants showed a 10- to 100-fold reduction in the efficiency of plating (EOP) as well as a reduced plaque size for the prolate phage c2 and were insensitive to the small isometric phage 712. A fifth Lac transconjugant demonstrated a similar reduced sensitivity to phage c2; however, this transconjugant was able to plaque phage 712, but with a reduced plaque size and EOP. The other five Lac transconjugants were sensitive to both c2 and 712 phages. The Suc transconjugant plaqued phage 712 with a reduced plaque size and EOP, but no reduction in plaque size or EOP was observed for phage c2. The Lac and reduced bacteriophage sensitivity (Rbs) phenotypes were correlated with specific plasmids in the Lac transconjugants. As four of the Lac transconjugants exhibited a phenotypically indistinguishable Rbs, one (AB001) was selected for further study. The Rbs in AB001 for both small isometric- and prolate-headed phages was not related to adsorption, and the reduced EOP for phage c2 was not related to the presence of a restriction and modification system. The latent period for phage c2 was unchanged, but the burst size was reduced 80%. The presence of the plasmid coding for Rbs retarded the lysis of a mitomycin C-induced prophage-containing strain. The Rbs mechanism appears to be abortive phage infection. This study supports previous observations that Rbs and conjugal transfer ability are physically linked among some group N streptococci. The results presented have implications in the identification of plasmids coding for Rbs and may also aid in explaining the dissemination of Rbs genes among lactic streptococci.
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Affiliation(s)
- M C Murphy
- Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, Minnesota 55108, and Department of Dairy and Food Microbiology, University College, Cork, Ireland
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3
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Coveney JA, Fitzgerald GF, Daly C. Detailed characterization and comparison of four lactic streptococcal bacteriophages based on morphology, restriction mapping, DNA homology, and structural protein analysis. Appl Environ Microbiol 2010; 53:1439-47. [PMID: 16347374 PMCID: PMC203889 DOI: 10.1128/aem.53.7.1439-1447.1987] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriophages uc1001 and uc1002, which are lytic for Streptococcus cremoris UC501 and UC502, respectively, were characterized in detail. Comparisons were made with a previously characterized phage, P008, which is lytic for Streptococcus lactis subsp. diacetylactis F7/2, and uc3001, which is a lytic phage for S. cremoris UC503. Phages uc1001 and uc1002 had small isometric heads (diameters, 52 and 50 nm, respectively) and noncontractile tails (lengths, 152 and 136 nm, respectively), and uc1002 also had a collar. Both had 30.1 +/- 0.6 kilobase pairs (kbp) of DNA with cross-complementary cohesive ends. Restriction endonuclease maps made with seven endonucleases showed no common fragments. Despite this there was a very high level of homology between uc1001 and uc1002, and results of cross-hybridization experiments showed that the organization of both phage genomes was similar. Heteroduplex analysis confirmed this and quantified the level of homology at 83%. The regions of nonhomology comprised 2.1-, 1.1-, and 1.0-kbp deletion loops and 13 smaller loops and bubbles. The sodium dodecyl sulfate-polyacrylamide gel electrophoretic structural protein profiles were related, with a major band of about 40,000 molecular weight and minor bands of 35,000 and 34,000 molecular weight in common. There were also differences, however, in that uc1001 had a second major band of 68,000 molecular weight and two extra minor bands. Except for the restriction maps, which were strain specific, phages uc1001, uc1002, and P008 were closely related by all the criteria listed above. Their DNAs also showed a very significant bias against the cleavage sites of 9 of 11 restriction endonucleases. Phage uc3001 was unrelated to uc1001, uc1002, or P008 in that it had a prolate head (53 by 39 nm) and a shorter tail (105 nm), contained approximately 22 kbp of DNA, had unrelated cohesive ends, showed no DNA homology with the isometric-headed phages, and displayed a very different structural protein profile.
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Affiliation(s)
- J A Coveney
- Department of Food Microbiology, University College, Cork, Ireland
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4
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Sing WD, Klaenhammer TR. Conjugal Transfer of Bacteriophage Resistance Determinants on pTR2030 into Streptococcus cremoris Strains. Appl Environ Microbiol 2010; 51:1264-71. [PMID: 16347085 PMCID: PMC239056 DOI: 10.1128/aem.51.6.1264-1271.1986] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Agar surface conjugal matings were used to introduce heat-sensitive phage resistance (Hsp) determinants carried on the conjugal plasmid pTR2030 into Streptococcus cremoris KH, HP, 924, and TDM1. Lactose-fermenting (Lac) transconjugants were selected from matings of Lac variants of S. cremoris KH, HP, 924, and TDM1 with Streptococcus lactis ME2 or a high-frequency donor, S. lactis T-EK1 (pTR1040, Lac; pTR2030, Hsp). For all of the S. cremoris strains examined, select Lac transconjugants were completely resistant to plaquing by their homologous lytic phages. In all cases the plaquing efficiencies were less than 10. Acquisition of a 30-megadalton plasmid (pTR2030) in the S. cremoris phage-resistant transconjugants was demonstrated by direct plasmid analysis, by hybridization with P-labeled probes, or by conjugal transfer of pTR2030 out of the phage-resistant transconjugants into a plasmid-cured recipient, S. lactis LM2302. Acid production, coagulation ability, and proteolytic activity of phage-resistant transconjugants in milk were comparable to those of their phage-sensitive parents. Further, S. cremoris phage-resistant transconjugants were not attacked by phage in starter culture activity tests, which included a 40 degrees C incubation period. The results demonstrated that phage resistance determinants on pTR2030 could be conjugally transferred to a variety of S. cremoris strains and confer resistance to phage under conditions encountered during cheese manufacture. Phage-resistant transconjugants of S. cremoris M43 and HP were also constructed without the use of antiblotic markers to select conjugal recipients from mating mixtures.
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Affiliation(s)
- W D Sing
- Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695-7624
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5
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Moineau S, Pandian S, Klaenhammer TR. Restriction/Modification systems and restriction endonucleases are more effective on lactococcal bacteriophages that have emerged recently in the dairy industry. Appl Environ Microbiol 2010; 59:197-202. [PMID: 16348842 PMCID: PMC202077 DOI: 10.1128/aem.59.1.197-202.1993] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recently, eight lytic small isometric-headed bacteriophages were isolated from cheese-manufacturing plants throughout North America. The eight phages were different, but all propagated on one strain, Lactococcus lactis NCK203. On the basis of DNA homology, they were classified in the P335 species. Digestion of their genomes in vitro with restriction enzymes resulted in an unusually high number of type II endonuclease sites compared with the more common lytic phages of the 936 (small isometric-headed) and c2 (prolate-headed) species. In vivo, the P335 phages were more sensitive to four distinct lactococcal restriction and modification (R/M) systems than phages belonging to the 936 and c2 species. A significant correlation was found between the number of restriction sites for endonucleases (purified from other bacterial genera) and the relative susceptibility of phages to lactococcal R/M systems. Comparisons among these three phage species indicate that the P335 species may have emerged most recently in the dairy industry.
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Affiliation(s)
- S Moineau
- Department of Food Science and Southeast Dairy Foods Research Center, North Carolina State University, Box 7624, Raleigh, North Carolina 27695-7624
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6
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Hill C, Massey IJ, Klaenhammer TR. Rapid method to characterize lactococcal bacteriophage genomes. Appl Environ Microbiol 2010; 57:283-8. [PMID: 16348396 PMCID: PMC182699 DOI: 10.1128/aem.57.1.283-288.1991] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present a rapid method to isolate and analyze bacteriophage DNA. Cells are infected and phage replication is allowed to proceed normally for 30 to 60 min. Prior to DNA packaging and cell bursts, the infected cells (1 ml) are harvested and lysed by using a combination of lysozyme and sodium dodecyl sulfate treatments. The total DNA recovered is enriched for phage genomes, and restriction fragments of the phage DNA can be readily visualized on agarose gels. This method was used to grossly compare the genomes of nine lactococcal phages isolated from different cheese plants at different times. The method was also used to visualize the inhibitory effects of pTR2030-induced abortive infection on the replication of phage nck202.31 in its homologous host, Lactococcus lactis NCK203.
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Affiliation(s)
- C Hill
- Departments of Food Science and Microbiology, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh, North Carolina 27695-7625
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7
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Gautier M, Chopin MC. Plasmid-Determined Systems for Restriction and Modification Activity and Abortive Infection in Streptococcus cremoris. Appl Environ Microbiol 2010; 53:923-7. [PMID: 16347351 PMCID: PMC203787 DOI: 10.1128/aem.53.5.923-927.1987] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus cremoris strain IL964 possessed a restriction and modification (R/M) activity which resulted in a bacteriophage efficiency of plating of 5 x 10. Phage sensitivity of protoplast-induced plasmid-cured derivatives indicated that two plasmids called pIL103 (5.7 kilobases) and pIL107 (15.2 kilobases) were each coding for one R/M system. Plasmid pIL103-encoded R/M was ascertained by transfer into the plasmid-free, R/M strain IL1403 of S. lactis, using protoplast cotransformation. This procedure failed for pIL107 because of some degree of incompatibility between pIL107 and the indicator plasmid pHV1301 used in cotransformation experiments. We also observed that plasmid pIL105 (8.7 kilobases) which showed no incidence on phage sensitivity in the parental strain IL964, mediated abortive infection in strain IL1403. In 97% of the infected cells, the phage infection was abortive, while in the remaining 3% phages were produced with a decreased burst size (50 instead of 180).
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Affiliation(s)
- M Gautier
- Laboratoire de Recherche de Technologie Laitière, Institut National de la Recherche Agronomique, 35042 Rennes, France
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8
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9
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Miklic A, Rogelj I. Characterization of lactococcal bacteriophages isolated from Slovenian dairies. Int J Food Sci Technol 2003. [DOI: 10.1046/j.1365-2621.2003.00676.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Kraus J, Geller B. Membrane Receptor for Prolate Phages is Not Required for Infection of Lactococcus lactis by Small or Large Isometric Phages. J Dairy Sci 1998. [DOI: 10.3168/jds.s0022-0302(98)70122-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Walker SA, Klaenhammer TR. Molecular characterization of a phage-inducible middle promoter and its transcriptional activator from the lactococcal bacteriophage phi31. J Bacteriol 1998; 180:921-31. [PMID: 9473048 PMCID: PMC106973 DOI: 10.1128/jb.180.4.921-931.1998] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
An inducible middle promoter from the lactococcal bacteriophage phi31 was isolated previously by shotgun cloning an 888-bp fragment (P15A10) upstream of the beta-galactosidase (beta-Gal) gene (lacZ.st) from Streptococcus thermophilus (D. J. O'Sullivan, S. A. Walker, S. G. West, and T. R. Klaenhammer, Bio/Technology 14:82-87, 1996). The promoter showed low levels of constitutive beta-Gal activity which could be induced two- to threefold over baseline levels after phage infection. During this study, the fragment was subcloned and characterized to identify a smaller, tightly regulated promoter fragment which allowed no beta-Gal activity until after phage infection. This fragment, defined within nucleotides 566 to 888 (P(566-888); also called fragment 566-888), contained tandem, phage-inducible transcription start sites at nucleotides 703 and 744 (703/744 start sites). Consensus -10 regions were present upstream of both start sites, but no consensus -35 regions were identified for either start site. A transcriptional activator, encoded by an open reading frame (ORF2) upstream of the 703/744 start sites, was identified for P(566-888). ORF2 activated P(566-888) when provided in trans in Escherichia coli. In addition, when combined with pTRK391 (P15A10::lacZ.st) in Lactococcus lactis NCK203, an antisense ORF2 construct was able to retard induction of the phage-inducible promoter as measured by beta-Gal activity levels. Finally, gel shift assays showed that ORF2 was able to bind to promoter fragment 566-888. Deletion analysis of the region upstream from the tandem promoters identified a possible binding site for transcriptional activation of the phage promoters. The DNA-binding ability of ORF2 was eliminated upon deletion of part of this region, which lies centered approximately 35 bp upstream of start site 703. Deletion analysis and mutagenesis studies also elucidated a critical region downstream of the 703/744 start sites, where mutagenesis resulted in a two- to threefold increase in beta-Gal activity. With these improvements, the level of expression achieved by an explosive-expression strategy was elevated from 3,000 to 11,000 beta-Gal units within 120 min after induction.
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Affiliation(s)
- S A Walker
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695-7624, USA
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12
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13
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Dinsmore PK, Klaenhammer TR. Molecular characterization of a genomic region in a Lactococcus bacteriophage that is involved in its sensitivity to the phage defense mechanism AbiA. J Bacteriol 1997; 179:2949-57. [PMID: 9139913 PMCID: PMC179059 DOI: 10.1128/jb.179.9.2949-2957.1997] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A spontaneous mutant of the lactococcal phage phi31 that is insensitive to the phage defense mechanism AbiA was characterized in an effort to identify the phage factor(s) involved in sensitivity of phi31 to AbiA. A point mutation was localized in the genome of the AbiA-insensitive phage (phi31A) by heteroduplex analysis of a 9-kb region. The mutation (G to T) was within a 738-bp open reading frame (ORF245) and resulted in an arginine-to-leucine change in the predicted amino acid sequence of the protein. The mutant phi31A-ORF245 reduced the sensitivity of phi31 to AbiA when present in trans, indicating that the mutation in ORF245 is responsible for the AbiA insensitivity of phi31A. Transcription of ORF245 occurs early in the phage infection cycles of phi31 and phi31A and is unaffected by AbiA. Expansion of the phi31 sequence revealed ORF169 (immediately upstream of ORF245) and ORF71 (which ends 84 bp upstream of ORF169). Two inverted repeats lie within the 84-bp region between ORF71 and ORF169. Sequence analysis of an independently isolated AbiA-insensitive phage, phi31B, identified a mutation (G to A) in one of the inverted repeats. A 118-bp fragment from phi31, encompassing the 84-bp region between ORF71 and ORF169, eliminates AbiA activity against phi31 when present in trans, establishing a relationship between AbiA and this fragment. The study of this region of phage phi31 has identified an open reading frame (ORF245) and a 118-bp DNA fragment that interact with AbiA and are likely to be involved in the sensitivity of this phage to AbiA.
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Affiliation(s)
- P K Dinsmore
- Department of Food Science, North Carolina State University, Raleigh 27695, USA
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14
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Daly C, Fitzgerald GF, Davis R. Biotechnology of lactic acid bacteria with special reference to bacteriophage resistance. Antonie Van Leeuwenhoek 1996; 70:99-110. [PMID: 8879402 DOI: 10.1007/bf00395928] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Lactic acid bacteria play an important role in many food and feed fermentations. In recent years major advances have been made in unravelling the genetic and molecular basis of significant industrial traits of lactic acid bacteria. Bacteriophages which can infect and destroy lactic acid bacteria pose a particularly serious threat to dairy fermentations that can result in serious economic losses. Consequently, these organisms and the mechanisms by which they interact with their hosts have received much research attention. This paper reviews some of the key discoveries over the years that have led us to our current understanding of bacteriophages themselves and the means by which their disruptive influence may be minimized.
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Affiliation(s)
- C Daly
- Department of Microbiology, University College, Cork, Ireland
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15
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Abstract
Lactic acid bacteria are industrial microorganisms used in many food fermentations. Lactococcus species are susceptible to bacteriophage infections that may result in slowed or failed fermentations. A substantial amount of research has focused on characterizing natural mechanisms by which bacterial cells defend themselves against phage. Numerous natural phage defense mechanisms have been identified and studied, and recent efforts have improved phage resistance by using molecular techniques. The study of how phages overcome these resistance mechanisms is also an important objective. New strategies to minimize the presence, virulence, and evolution of phage are being developed and are likely to be applied industrially.
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Affiliation(s)
- P K Dinsmore
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695-7624, USA
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16
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Durmaz E, Klaenhammer TR. A Starter Culture Rotation Strategy Incorporating Paired Restriction/ Modification and Abortive Infection Bacteriophage Defenses in a Single Lactococcus lactis Strain. Appl Environ Microbiol 1995; 61:1266-73. [PMID: 16534987 PMCID: PMC1388405 DOI: 10.1128/aem.61.4.1266-1273.1995] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three derivatives of Lactococcus lactis subsp. lactis NCK203, each with a different pair of restriction/ modification (R/M) and abortive infection (Abi) phage defense systems, were constructed and then rotated in repeated cycles of a milk starter culture activity test (SAT). The rotation proceeded successfully through nine successive SATs in the presence of phage and whey containing phage from previous cycles. Lactococcus cultures were challenged with 2 small isometric-headed phages, (phi)31 and ul36, in one rotation series and with a composite of 10 industrial phages in another series. Two native lactococcal R(sup+)/M(sup+) plasmids, pTRK68 and pTRK11, and one recombinant plasmid, pTRK308, harboring a third distinct R/M system were incorporated into three NCK203 derivatives constructed separately for the rotation. The R(sup+)/M(sup+) NCK203 derivatives were transformed with high-copy-number plasmids encoding four Abi genes, abiA, abiC, per31, and per50. Various Abi and R/M combinations constructed in NCK203 were evaluated for their effects on cell growth, level of phage resistance, and retardation of phage development during repeated cycles of the SAT. The three NCK203 derivatives chosen for use in the SAT exhibited additive effects of the R/M and Abi phenotypes against sensitive phages. In such combinations, phage escaping restriction are prevented from completing their infective cycle by an abortive response that kills the host cell. The rotation series successfully controlled modified, recombinant, and mutant phages which were resistant to any one of the individual defense systems by presenting a different set of R/M and Abi defenses in the next test of the rotation.
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17
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Design and implementation of a strategy to reduce bacteriophage infection of dairy starter cultures. Int Dairy J 1995. [DOI: 10.1016/0958-6946(95)00039-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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18
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Dinsmore PK, Klaenhammer TR. Phenotypic Consequences of Altering the Copy Number of
abiA
, a Gene Responsible for Aborting Bacteriophage Infections in
Lactococcus lactis. Appl Environ Microbiol 1994; 60:1129-36. [PMID: 16349225 PMCID: PMC201449 DOI: 10.1128/aem.60.4.1129-1136.1994] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The
abiA
gene (formerly
hsp
) encodes an abortive phage infection mechanism which inhibits phage DNA replication. To analyze the effects of varying the
abiA
gene dosage on bacteriophage resistance in
Lactococcus lactis
, various genetic constructions were made. An IS
946
-based integration vector, pTRK75, was used to integrate a single copy of
abiA
into the chromosomes of two lactococcal strains, MG1363 and NCK203. In both strains, a single copy of
abiA
did not confer any significant phage resistance on the host except for one of the MG1363 integrants, NCK625, which exhibited a slightly higher level of resistance to phages sk1 and p2. Hybridization of the total cellular RNA from NCK625 to an
abiA
-specific probe indicated that the integration took place downstream of a promoter causing stronger expression of
abiA
in this integrant. Three
abiA
-containing plasmids of various copy numbers were introduced into both strains, and the recombinants were evaluated for resistance to phages c2, p2, sk1, and φ31. Plasmid pTRK18 has a copy number of approximately six (
cn
= 6) and caused a decreased plaque size for all phages evaluated. Integration of pTRK75 into a native plasmid of NCK203 generated pTRK362 (
cn
= 13), which caused a reduced efficiency of plaquing (EOP = 10
-2
) and reduced plaque size. A high-copy-number
abiA
plasmid (pTRK363), based on the pAMβ1 origin of replication, was also constructed (
cn
= 100). Plasmid pTRK363 caused a significant reduction in EOP (10
-4
to 10
-8
) and plaque size for all phages tested, although in some cases, this plasmid caused the evolution of AbiA-resistant phage derivatives. Altering the gene dosage or expression level of
abiA
significantly affects the phage resistance levels.
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Affiliation(s)
- P K Dinsmore
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Box 7624, Raleigh, North Carolina 27695
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19
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O'sullivan DJ, Hill C, Klaenhammer TR. Effect of Increasing the Copy Number of Bacteriophage Origins of Replication, in
trans
, on Incoming-Phage Proliferation. Appl Environ Microbiol 1993; 59:2449-56. [PMID: 16349010 PMCID: PMC182305 DOI: 10.1128/aem.59.8.2449-2456.1993] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriophage resistance mechanisms which are derived from a bacteriophage genome are termed Per (phage-encoded resistance). When present in
trans
in
Lactococcus lactis
NCK203, Per50, the cloned origin of replication from phage φ50, interferes with φ50 replication. The
per50
fragment was found to afford negligible protection to NCK203 against φ50 infection when present in a low-copy-number plasmid, pTRK325. A high-copy-number Per50 construct (pTRK323) dramatically affected φ50 infection, reducing the efficiency of plaquing (EOP) to 2.5 × 10
-4
and the plaque size to pinhead proportions. This clone also afforded significant protection against other related small isometric phages. Per31 was cloned from phage φ31 and demonstrated to function as an origin of replication by enabling replication of
per31
-containing plasmids, in NCK203, on φ31 infection. A low-copy-number Per31 plasmid (pTRK360) reduced the EOP of φ31 on NCK203 to 0.3 and the plaque diameter from 1.5 to 0.5 mm. When this plasmid was cloned in high copy number, the EOP was further reduced to 7.2 × 10
-7
but the plaques were large and contained Per31-resistant phages. Characterization of these “new” phages revealed at least two different types that were similar to φ31, except that DNA alterations were noted in the region containing the origin. This novel and powerful abortive phage resistance mechanism should prove useful when directed at specific, problematic phages.
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Affiliation(s)
- D J O'sullivan
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh, North Carolina 27695-7624
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20
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Jarvis AW, Collins LJ, Ackermann HW. A study of five bacteriophages of the Myoviridae family which replicate on different gram-positive bacteria. Arch Virol 1993; 133:75-84. [PMID: 8240019 DOI: 10.1007/bf01309745] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A comparative study is reported on five phages of the Myoviridae family which propagate on Bacillus subtilis, B. thuringiensis, Enterococcus sp., Lactobacillus plantarum, or Staphylococcus aureus. The phages are morphologically identical and characterized by isometric heads with conspicuous capsomers and by contractile tails with complex base plates. The phages show similar protein profiles, but vary considerably in burst size. Phage DNAs are about 95-166 kb in size and are unrelated by DNA-DNA hybridization and restriction endonuclease analysis. Therefore the phages are unrelated at species level. Implications of these data for our understanding of the development of phage species are discussed.
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Affiliation(s)
- A W Jarvis
- New Zealand Dairy Research Institute, Palmerston North
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21
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Sing WD, Klaenhammer TR. A Strategy for Rotation of Different Bacteriophage Defenses in a Lactococcal Single-Strain Starter Culture System. Appl Environ Microbiol 1993; 59:365-72. [PMID: 16348864 PMCID: PMC202114 DOI: 10.1128/aem.59.2.365-372.1993] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A new strategy for starter culture rotations was developed for a series of phage-resistant clones genetically derived from a single strain of
Lactococcus lactis
subsp.
lactis.
Phage-resistant derivatives carrying different defense systems were constructed via conjugation with various plasmids encoding abortive infection (Abi/Hsp) and/or restriction and modification (R/M) systems of different specificity. The plasmids included pTR2030 (Hsp
+
R
+
/M
+
), pTN20 (Abi
+
R
+
/M
+
), pTRK11 (R
+
/M
+
), and pTRK68 (R
+
/M
+
). Selected phage-resistant transconjugants or transformants were evaluated in different rotation sequences through cycles of the Heap-Lawrence starter culture activity test in milk contaminated with phage and whey from the previous cycle. When used in consecutive sequence, derivative strains carrying the R/M systems encoded by pTN20, pTRK11, and pTRK68 retarded phage development when the initial levels of phage contamination were below 10
2
PFU/ml but not when levels were increased to 10
3
PFU/ml. Use of a derivative bearing pTR2030 (Hsp
+
R
+
/M
+
) at the beginning of the rotation prevented phage development, even when the initial levels of phage contamination were high (10
6
PFU/ml). Alternating the type and specificity of R/M and Abi defenses through the rotation prevented phage proliferation and in some cases eliminated contaminating phages. A model rotation sequence for the phage defense rotation strategy was developed and performed successfully over nine cycles of the Heap-Lawrence starter culture activity test in the presence of high-titer commercial phage composites. This phage defense rotation strategy is designed to protect a highly specialized
Lactococcus
strain from phage attack during continuous and extended use in the dairy industry.
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Affiliation(s)
- W D Sing
- Department of Microbiology, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh, North Carolina 27695-7624
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22
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Durmaz E, Higgins DL, Klaenhammer TR. Molecular characterization of a second abortive phage resistance gene present in Lactococcus lactis subsp. lactis ME2. J Bacteriol 1992; 174:7463-9. [PMID: 1429469 PMCID: PMC207445 DOI: 10.1128/jb.174.22.7463-7469.1992] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
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.
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Affiliation(s)
- E Durmaz
- Department of Food Science North Carolina State University, Raleigh 27695-7624
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23
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Kim JH, Kim SG, Chung DK, Bor YC, Batt CA. Use of antisense RNA to confer bacteriophage resistance in dairy starter cultures. ACTA ACUST UNITED AC 1992; 10:71-8. [PMID: 1368478 DOI: 10.1007/bf01583838] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The strategy and implementation of a unique system for engineering bacteriophage resistant starter cultures of Lactococcus lactis employing antisense RNA is reviewed. As a necessary prerequisite for developing this system, we have cloned and sequenced a number of bacteriophage genes coding for minor and major structural proteins. In addition, we have also identified a series of genes whose function(s) is not known but their sequences appear to be conserved in a vast number of isolates. One of these latter sequences, designated gp51C, codes for a 51-kDa protein which is extremely charged and shares some homology with yeast translation initiation factor. Resistance to a broad class of isometric bacteriophages has been achieved by expression of an antisense RNA targeted against, for example, gp51C. In the best case, expression of the antisense gp51C RNA results is a greater than 99% reduction in the total number of plaque forming units. Additional antisense RNA constructs directed against other bacteriophage genes, including the major capsid protein, also appear effective at inhibiting infection from 40-55% suggesting that this approach may prove useful for engineering a set of truly isogenic strains to be used in a starter culture rotation plan.
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Affiliation(s)
- J H Kim
- Department of Food Science, Cornell University, Ithaca, NY 14853
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24
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Conjugal transfer of bacteriophage resistance to prolate phages in Lactococcus lactis. Food Microbiol 1992. [DOI: 10.1016/0740-0020(92)80053-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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25
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Larbi D, Decaris B, Simonet JM. Different bacteriophage resistance mechanisms in Streptococcus salivarius subsp. thermophilus. J DAIRY RES 1992; 59:349-57. [PMID: 1328335 DOI: 10.1017/s0022029900030624] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Streptococcus salivarius subsp. thermophilus strain NST5 exhibited a temperature-dependent defence mechanism against the virulent bacteriophages phi B1.2 and phi A1.1. It was active at 42 degrees C but not at 30 degrees C as demonstrated by a significant increase of both plaque size and efficiency of plaquing. This defence mechanism did not affect host-dependent phage replication and did not interfere with phage adsorption to NST5. These results suggest that it interfered with phage development. The phages phi T33, phi T58, phi D1, phi T21 and phi T9, belonging to the same phage type as phi B1.2, were examined for their ability to infect NST3 and NST5. Restriction modification systems of different specificity were detected in NST3 and NST5; host-dependent phage replication was detected at 30 and 42 degrees C; an abortive defence mechanism was detected in NST5 which was active at 42 degrees C, but not 30 degrees C, and was independent of restriction modification action or interference with phage adsorption. Our investigations of phage-host interactions showed that the two Str. salivarius subsp. thermophilus strains studied avoided attack by related bacteriophages by evolving at least three different resistance systems.
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Affiliation(s)
- D Larbi
- Laboratoire de Génétique et Microbiologie, Faculté des Sciences, Université Nancy I, Vandoeuvre-lès-Nancy, France
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26
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Kim SG, Bor YC, Batt CA. Bacteriophage resistance in Lactococcus lactis ssp. lactis using antisense ribonucleic acid. J Dairy Sci 1992; 75:1761-7. [PMID: 1500572 DOI: 10.3168/jds.s0022-0302(92)77935-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Antisense RNA against a conserved bacteriophage gene when expressed in a Lactococcus lactis ssp. lactis strain renders it resistant to bacteriophage infection. Two open reading frames have been identified in a L. lactis ssp. lactis bacteriophage that are conserved in a majority of isolates. They code for an 18-kDa (designated GP18C) protein and a 24-kDa (GP24C) protein, respectively, which are arranged along with previously identified open reading frames in a tandem motif similar to other bacteriophages. The presence of gp18C and gp24C in a number of bacteriophage isolates was confirmed by polymerase chain reaction using primers specific for these regions. Plasmids bearing various fragments of gp18C, gp24C, or both were constructed such that the respective open reading frames were positioned in the antisense direction relative to the Lactococcus lactis ssp. cremoris Wg2 promoter, p59. These antisense RNA-producing vectors inhibited the efficiency of plaquing of L. lactis ssp. lactis bacteriophage phi 7-9 up to 50%; the resulting plaques were extremely small and irregular in shape. The replication of the bacteriophage was severely inhibited, and the total number decreased over the first 3 h during infection in strains expressing antisense RNA compared with the host strain alone, in which the bacteriophage number increased 10(4)-fold.
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Affiliation(s)
- S G Kim
- Department of Food Science, Cornell University, Ithaca, NY 14853
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27
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Hill C, Miller LA, Klaenhammer TR. In vivo genetic exchange of a functional domain from a type II A methylase between lactococcal plasmid pTR2030 and a virulent bacteriophage. J Bacteriol 1991; 173:4363-70. [PMID: 1906061 PMCID: PMC208097 DOI: 10.1128/jb.173.14.4363-4370.1991] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The conjugative plasmid pTR2030 confers bacteriophage resistance to lactococci by two independent mechanisms, an abortive infection mechanism (Hsp+) and a restriction and modification system (R+/M+). pTR2030 transconjugants of lactococcal strains are used in the dairy industry to prolong the usefulness of mesophilic starter cultures. One bacteriophage which has emerged against a pTR2030 transconjugant is not susceptible to either of the two defense systems encoded by the plasmid. Phage nck202.50 (phi 50) is completely resistant to restriction by pTR2030. A region of homology between pTR2030 and phi 50 was subcloned, physically mapped, and sequenced. A region of 1,273 bp was identical in both plasmid and phage, suggesting that the fragment had recently been transferred between the two genomes. Sequence analysis confirmed that the transferred region encoded greater than 55% of the amino domain of the structural gene for a type II methylase designated LlaI. The LlaI gene is 1,869 bp in length and shows organizational similarities to the type II A methylase FokI. In addition to the amino domain, upstream sequences, possibly containing the expression signals, were present on the phage genome. The phage phi 50 fragment containing the methylase amino domain, designated LlaPI, when cloned onto the shuttle vector pSA3 was capable of modifying another phage genome in trans. This is the first report of the genetic exchange between a bacterium and a phage which confers a selective advantage on the phage. Definition of the LlaI system on pTR2030 provides the first evidence that type II systems contribute to restriction and modification phenotypes during host-dependent replication of phages in lactococci.
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Affiliation(s)
- C Hill
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695-7624
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28
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29
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Hill C, Miller LA, Klaenhammer TR. The bacteriophage resistance plasmid pTR2030 forms high-molecular-weight multimers in lactococci. Plasmid 1991; 25:105-12. [PMID: 1857750 DOI: 10.1016/0147-619x(91)90021-n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Lactococcus lactis ME2 can transfer a 46-kb plasmid, pTR2030, which encodes abortive phage infection (Hsp) and restriction/modification (R/M) activities. pTR2030 can be detected as a monomeric plasmid in transconjugants at low copy number, but not in ME2. pTR2030-specific probes were cloned and used to determine the location of the element in ME2. No homology was observed between these pTR2030-specific probes and the CsCl-purified plasmid content of ME2. However, probes specific for pTR2030 hybridized strongly to a high-molecular-weight moiety, and not to chromosomal DNA, in total DNA isolated by a gentle lysis procedure. The absence of junction fragments indicates that pTR2030 forms high-molecular-weight multimers in lactococci. A phage-sensitive derivative of ME2, L. lactis N1, is cured of pTR2030 and no longer possesses the high-molecular-weight species. When pTR2030 was reintroduced to N1 via conjugation, an ME2-like phage-insensitive phenotype was restored. pTR2030 could remain as a detectable monomeric plasmid in the N1 transconjugants or could revert to the high-molecular-weight structure.
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Affiliation(s)
- C Hill
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695-7625
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30
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Hill C, Miller LA, Klaenhammer TR. Cloning, expression, and sequence determination of a bacteriophage fragment encoding bacteriophage resistance in Lactococcus lactis. J Bacteriol 1990; 172:6419-26. [PMID: 2121714 PMCID: PMC526828 DOI: 10.1128/jb.172.11.6419-6426.1990] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A number of host-encoded phage resistance mechanisms have been described in lactococci. However, the phage genome has not been exploited as a source of additional resistance determinants. A 4.5-kb BamHI-HindIII fragment of phage nck202.50 (phi 50) was subcloned in streptococcus-Escherichia coli shuttle plasmid pSA3 and introduced into Lactococcus lactis NCK203 and MG1363 by protoplast transformation. This cloned phage fragment directed a bacteriophage resistance phenotype designated Per (phage-encoded resistance). Both phi 50 and a distantly related phage, nck202.48 (phi 48), formed small plaques on strain NCK213 at a slightly reduced efficiency of plaquing on the Per+ host. The per locus was further reduced to a 1.4-kb fragment through in vitro deletion analysis. The 1.4-kb fragment was sequenced, and the Per phenotype was found to be associated with a ca. 500-bp region rich in direct and inverted repeats. We present evidence that the Per region contains a phage origin of replication which, in trans, may interfere with phage replication by titration of DNA polymerase or other essential replication factors. It was demonstrated that the Per+ phenotype is not a result of reduced adsorption or action of a restriction and modification system. Per+ activity was not detected against six independent phages which were previously shown to be sensitive to the Hsp+ mechanism. The mutually exclusive resistance mechanisms could be combined to confer resistance to both types of phages (Hsp resistant and Per resistant) in a single host. This is the first description in lactococci of a phage resistance phenotype, other than superinfection immunity, originating from a lactococcal phage genome.
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Affiliation(s)
- C Hill
- Department of Food Science, Southeast Center for Dairy Foods Research, North Carolina State University, Raleigh 27695-7624
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31
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32
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Valyasevi R, Sandine WE, Geller BL. The bacteriophage kh receptor of Lactococcus lactis subsp. cremoris KH is the rhamnose of the extracellular wall polysaccharide. Appl Environ Microbiol 1990; 56:1882-9. [PMID: 2116761 PMCID: PMC184526 DOI: 10.1128/aem.56.6.1882-1889.1990] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A receptor for bacteriophages of lactic acid bacteria, including Lactococcus lactis subsp. cremoris KH, was found on the cell wall and not on the cell membrane, as determined by a phage-binding assay of sodium dodecyl sulfate- and mutanolysin-treated cell walls. The cell wall carbohydrates of L. lactis subsp. cremoris KH were analyzed by gas chromatography and mass spectrometry and found to contain rhamnose, galactose, glucose and N-acetylglucosamine. Similar analysis of mutants that were reduced in the ability to bind phages kh, 643, c2, ml3, and 1 indicated that galactose was essential for binding all phages. In addition, rhamnose was required for binding phages kh and ml3. Inhibition studies of phage binding by using two different lectins with a specificity for galactose indicated that phage kh may not bind directly to galactose. Rather, galactose may be an essential structural component located in the vicinity of the receptor. Incubation of any of the five phages with rhamnose or of phage kh with purified cell walls inactivated the phages. Inactivation required divalent cations and was irreversible. Inactivation of phages was stereospecific for rhamnose, as neither L-(+)- nor D-(-)-fucose (the stereoisomers of rhamnose) inhibited the phage. Furthermore, phage infection of a culture was completely inhibited by the addition of rhamnose to the medium. Therefore, the receptor for phage kh appears to be a rhamnose component of the extracellular wall polysaccharide.
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Affiliation(s)
- R Valyasevi
- Department of Microbiology, Oregon State University, Corvallis 97331-3804
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33
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Klaenhammer TR. Genetic Characterization of Multiple Mechanisms of Phage Defense from a Prototype Phage-Insensitive Strain, Lactococcus lactis ME2. J Dairy Sci 1989. [DOI: 10.3168/jds.s0022-0302(89)79505-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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34
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McKay LL, Bohanon MJ, Polzin KM, Rule PL, Baldwin KA. Localization of Separate Genetic Loci for Reduced Sensitivity towards Small Isometric-Headed Bacteriophage sk1 and Prolate-Headed Bacteriophage c2 on pGBK17 from
Lactococcus lactis
subsp.
lactis
KR2. Appl Environ Microbiol 1989; 55:2702-9. [PMID: 16348036 PMCID: PMC203147 DOI: 10.1128/aem.55.10.2702-2709.1989] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism of reduced sensitivity to the small isometric-headed bacteriophage sk1 encoded on a 19-kilobase (kb)
Hpa
II fragment subcloned from pKR223 of
Lactococcus lactis
subsp.
lactis
KR2 was examined. The reduced sensitivity to phage sk1 was due to a modest restriction/modification (R/M) system that was not active against prolate-headed phage c2. The genetic loci for the R/M system against sk1 and the abortive phage infection (Abi) mechanism effective against phage c2 were then localized by restriction mapping, subcloning, and deletion analysis. The restriction gene was localized to a region of a 2.7-kb
Eco
RV fragment and included an
Eco
RI site within that fragment. The modification gene was found to be physically separable from the restriction gene and was present on a 1.75-kb
Bst
EII-
Xba
I fragment. The genetic locus for the Abi phenotype against phage c2 was localized to a region containing a 1.3-kb
Eco
RI fragment. Attempts to clone the c2 Abi mechanism independent of the sk1 R/M system were unsuccessful, suggesting that expression of the
abi
genes required sequences upstream of the modification gene. Some pGBK17 (vector pGB301 plus a 19-kb
Hpa
II insert fragment) transformants exhibited the R/M system against phage sk1 but lost the Abi mechanism against phage c2. These transformants contained a 1.2- to 1.3-kb insertion in the Abi region. The data identified genetic loci on a cloned 19-kb
Hpa
II fragment responsible for restriction activity and for modification activity against a small isometric-headed phage and for Abi activity against prolate-headed phage c2. A putative insertion element was also found to inactivate the
abi
gene(s).
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Affiliation(s)
- L L McKay
- Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, Minnesota 55108
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35
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Hill C, Pierce K, Klaenhammer TR. The conjugative plasmid pTR2030 encodes two bacteriophage defense mechanisms in lactococci, restriction modification (R+/M+) and abortive infection (Hsp+). Appl Environ Microbiol 1989; 55:2416-9. [PMID: 2508558 PMCID: PMC203092 DOI: 10.1128/aem.55.9.2416-2419.1989] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
pTR2030 is a conjugative plasmid which encodes resistance to bacteriophage in lactococci by a mechanism that aborts the phage infection (Hsp+). Subcloning and in vivo deletion events showed that two independent mechanisms of resistance are located on a 13.6-kilobase Bg/II fragment cloned in pSA3; one mechanism is responsible for the abortive infection, and the other incodes a restriction modification system. The introduction of pTR2030 or the recombinant plasmid pTK6 resulted in the loss of a resident restriction modification plasmid in Lactococcus lactis NCK202 which was not previously identified.
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Affiliation(s)
- C Hill
- Department of Food Science, North Carolina State University, Raleigh 27695-7624
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36
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Abstract
Conjugal transfer of genetic material by Lactococcus lactis subsp. lactis 11007 was examined. A plasmid of 88 MDa (pJS88) was identified in addition to the previously reported conjugally transferred plasmids of 32 (pKB32) and 4.8 MDa. Proteinase activity, reduced bacteriophage sensitivity, bacteriocin resistance, and conjugal transfer ability were encoded by pJS88. The ability to metabolize lactose (Lac+) was encoded by pKB32, and the 4.8-MDa plasmid was cryptic. When a strain containing both pKB32 and pJS88 was mated with a recipient deficient in host-mediated homologous recombination (Rec-), a plasmid of 40 MDa (pJS40) was observed in approximately 50% of the Lac+ transconjugants. DNA-DNA hybridization results indicated that pJS40 contained homology with both pKB32 and pJS88. These results indicated that pKB32 was conjugally transferred via conduction and suggested that pJS40 is a deletion derivative of a pKB32::pJS88 cointegrate. A Rec- strain containing pKB32 and pJS88 mediated Lac+ conjugal transfer, suggesting that the pKB32::pJS88 cointegrate could form via a rec-independent event. Resolution of the pKB32::pJS88 cointegrate was observed in both Rec- and Rec+ hosts. Cointegrate formation and resolution via rec-independent mechanisms suggest the involvement of a transposable element in the Tn3 family.
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Affiliation(s)
- J L Steele
- Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108
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37
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Hill C, Romero DA, McKenney DS, Finer KR, Klaenhammer TR. Localization, cloning, and expression of genetic determinants for bacteriophage resistance (Hsp) from the conjugative plasmid pTR2030. Appl Environ Microbiol 1989; 55:1684-9. [PMID: 2504114 PMCID: PMC202935 DOI: 10.1128/aem.55.7.1684-1689.1989] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Genetic determinants for a bacteriophage resistance mechanism (Hsp+) encoded by plasmid pTR2030 (46.2 kilobases [kb]) were localized by mapping an 11.5-kb deletion that accompanied the transition of Lactococcus lactis LMA12-4 transconjugants (M. E. Sanders, P. J. Leonard, W. D. Sing, and T. R. Klaenhammer, Appl. Environ. Microbiol. 52:1001-1007, 1986) from phage resistance to phage sensitivity. The deleted 34.7-kb replicon (pTR2023, Hsp-) retained its conjugative ability, demonstrating that the phage resistance and conjugal transfer determinants were genetically distinct. The Hsp region of pTT2030, which was contained within a 13.6-kb BglII fragment, was cloned into the BamHI site of bacteriophage lambda EMBL3, and Hsp was subcloned into the Escherichia coli-Streptococcus shuttle vector pSA3. The recombinant plasmids pTK6 and pTK9 were recovered in E. coli HB101 and contained a 13.6-kb insert in opposite orientations. L. Lactis MG1363 transformants carrying pTK6 or pTK9 exhibited a significant reduction in plaque size, in addition to a slight reduction in the efficiency of plaquing for both prolate and small isometric phages. Phenotypic reactions observed for the recombinant plasmids suggest that pTR2030-encoded Hsp acts similarly against both prolate and small isometric phages. Tn5 mutagenesis was used to define the region essential for the expression of the Hsp+ phenotype. Any of four insertions within a 3-kb region resulted in the loss of phage resistance, whereas a further 26 insertions outside this locus had no effect on Hsp expression. In vitro deletion analysis confirmed that the 3-kb region contained all the information necessary for the observed resistance.
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Affiliation(s)
- C Hill
- Department of Food Science, Southeast Dairy Foods Research Center, North Carolina State University, Raleigh 27695-7624
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38
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Jarvis AW, Heap HA, Limsowtin GK. Resistance against Industrial Bacteriophages Conferred on Lactococci by Plasmid pAJ1106 and Related Plasmids. Appl Environ Microbiol 1989; 55:1537-43. [PMID: 16347947 PMCID: PMC202900 DOI: 10.1128/aem.55.6.1537-1543.1989] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmid pAJ1106 and its deletion derivative, plasmid pAJ2074, conferred lactose-fermenting ability (Lac) and bacteriophage resistance (Hsp) at 30°C to Lac
−
proteinase (Prt)-negative
Lactococcus lactis
subsp.
lactis
and
L. lactis
subsp.
lactis
var.
diacetylactis
recipient strains. An additional plasmid, pAJ331, isolated from the original source strain of pAJ1106, retained Hsp and conjugative ability without Lac. pAJ331 was conjugally transferred to two
L. lactis
subsp.
lactis
and one
L. lactis
subsp.
cremoris
starter strains. The transconjugants from such crosses acquired resistance to the phages which propagated on the parent recipient strains. Of 10 transconjugant strains carrying pAJ1106 or one of the related plasmids, 8 remained insensitive to phages through five activity test cycles in which cultures were exposed to a large number of industrial phages at incubation temperatures used in lactic casein manufacture. Three of ten strains remained phage insensitive through five cycles of a cheesemaking activity test in which cultures were exposed to approximately 80 different phages through cheesemaking temperatures. Three phages which propagated on transconjugant strains during cheesemaking activity tests were studied in detail. Two were similar (prolate) in morphology and by DNA homology to phages which were shown to be sensitive to the plasmid-encoded phage resistance mechanism. The third phage was a long-tailed, small isometric phage of a type rarely found in New Zealand cheese wheys. The phage resistance mechanism was partially inactivated in most strains at 37°C.
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Affiliation(s)
- A W Jarvis
- New Zealand Dairy Research Institute, Palmerston North, New Zealand
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39
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Josephsen J, Vogensen FK. Identification of three different plasmid-encoded restriction/modification systems in Streptococcus lactis subsp. cremoris W56. FEMS Microbiol Lett 1989. [DOI: 10.1111/j.1574-6968.1989.tb03102.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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40
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Higgins DL, Sanozky-Dawes RB, Klaenhammer TR. Restriction and modification activities from Streptococcus lactis ME2 are encoded by a self-transmissible plasmid, pTN20, that forms cointegrates during mobilization of lactose-fermenting ability. J Bacteriol 1988; 170:3435-42. [PMID: 2841286 PMCID: PMC211312 DOI: 10.1128/jb.170.8.3435-3442.1988] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A self-transmissible (Tra+) plasmid encoding determinants for restriction and modification activities (R+/M+) from Streptococcus lactis ME2 was isolated and characterized. The 28-kilobase (kb) plasmid (pTN20) was detected in lactose-fermenting (Lac+) transconjugants generated from matings between S. lactis N1, and ME2 variant, and a plasmid-free recipient, S. lactis LM2301. The plaquing efficiencies of prolate- and small isometric-headed phages were reduced on transconjugants containing either pTN20 (R+/M+ Tra+) or 100-kb plasmids encoding Lac+, R+/M+, and Tra+. Lac+ transconjugants which harbored pTR1040 (Lac+) and pTN20 (R+/M+) were phenotypically R-/M- and transferred Lac+ at low frequency in subsequent matings to give rise to 100-kb R+/M+ plasmids. R+/M+ activities and high-frequency conjugal transfer ability were detected in Lac+ transconjugants that contained pTR1041 (Lac+) and pTN20 (R+/M+). No 100-kb R+/M+ plasmids were recovered after these matings, suggesting that pTR1041 was mobilized by pTN20 through a process that resembled plasmid donation. pTR1041 was identical to pTR1040 but contained an additional 3.3-kb DNA fragment. These data suggested that phenotypic expression of R+/M+ and Tra+ is affected by coresident Lac+ plasmids. Restriction enzyme analysis and hybridization reactions demonstrated that the 100-kb R+/M+ plasmid was formed by a cointegration event between pTR1040 (Lac+) and pTN20 (R+/M+ Tra+) during conjugal transfer via a conductive-type process. This is the first report that defines self-transmissible restriction and modification plasmids in the lactic streptococci.
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Affiliation(s)
- D L Higgins
- Department of Food Science, North Carolina State University, Raleigh 27695-7624
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41
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Jarvis AW. Conjugal Transfer in Lactic Streptococci of Plasmid-Encoded Insensitivity to Prolate- and Small Isometric-Headed Bacteriophages. Appl Environ Microbiol 1988; 54:777-783. [PMID: 16347585 PMCID: PMC202540 DOI: 10.1128/aem.54.3.777-783.1988] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eight of 40 strains of
Streptococcus lactis
and
S. lactis
subsp.
diacetylactis
were able to conjugally transfer a degree of phage insensitivity to
Streptococcus lactis
LM0230. Transconjugants from one donor strain,
S. lactis
subsp.
diacetylactis
4942, contained a 106-kilobase (kb) cointegrate plasmid, pAJ1106. The plasmid was conjugative (Tra
+
) and conferred phage insensitivity (Hsp) and lactose-fermenting ability (Lac) in
S. lactis
and
Streptococcus cremoris
transconjugants. The phage resistance mechanism was effective against prolate- and small isometric-headed phages at 30°C. In
S. lactis
transconjugants, the phage resistance mechanism was considerably weakened at elevated temperatures. A series of deletion plasmids was isolated from transconjugants in
S. cremoris
4854. Deletion plasmids were pAJ2074 (74 kb), Lac
+
, Hsp
+
, Tra
+
; pAJ3060 (60 kb), Lac
+
, Hsp
+
; and pAJ4013 (13 kb), Lac
+
. These plasmids should facilitate mapping Hsp and
tra
genes, with the aim of constructing phage-insensitive strains useful to the dairy industry.
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Affiliation(s)
- Audrey W Jarvis
- New Zealand Dairy Research Institute, Palmerston North, New Zealand
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42
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Froseth BR, Harlander SK, McKay LL. Plasmid-mediated reduced phage sensitivity in Streptococcus lactis KR5. J Dairy Sci 1988; 71:275-84. [PMID: 3132485 DOI: 10.3168/jds.s0022-0302(88)79555-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The phage insensitivity of Streptococcus lactis KR5 was evaluated for its possible linkage to plasmid DNA. This strain possessed plasmids of 40, 29, 26, 21, 16.5, 10.5, 7.8, and 1.5 Mdal. Plasmid curing using novobiocin resulted in derivatives with increased sensitivity to prolate-headed phage, suggesting the involvement of plasmid DNA in phage insensitivity. Transformation of S. lactis LM0230 protoplasts with the KR5 plasmid DNA pool produced transformants containing a plasmid of about 27 Mdal. These erythromycin-resistant transformants were lactose-positive phage-sensitive or were lactose-negative and exhibited a reduced sensitivity to phage. Agarose gel electrophoresis and restriction endonuclease digestion analysis showed the 27-Mdal plasmid band to be composed of two distinct plasmids of 26 Mdal (pBF61) and 29 Mdal (pBF62), which coded for reduced phage sensitivity and lactose-positive phenotypes, respectively. The mechanisms of reduced phage sensitivity encoded by pBF61 included a restriction/modification system and a mechanism that resulted in reduced plaque size independent of incubation temperature. These results further support the involvement of plasmid DNA in the mechanisms for reduced phage sensitivity in dairy streptococci.
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Affiliation(s)
- B R Froseth
- Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108
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43
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Laible NJ, Rule PL, Harlander SK, McKay LL. Identification and Cloning of Plasmid Deoxyribonucleic Acid Coding for Abortive Phage Infection from Streptococcus lactis ssp. diacetylactis KR2. J Dairy Sci 1987. [DOI: 10.3168/jds.s0022-0302(87)80280-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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44
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Shieh YS, Dunny G, Ledford R, Walsh P. Sensitivity of Commercial Cheddar Cheese Starter Isolates to Bacteriophage Associated with Wheys. J Dairy Sci 1987. [DOI: 10.3168/jds.s0022-0302(87)80249-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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45
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Sandine WE. Looking backward and forward at the practical applications of genetic researches on lactic acid bacteria. FEMS Microbiol Lett 1987. [DOI: 10.1111/j.1574-6968.1987.tb02461.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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46
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Klaenhammer TR. Plasmid-directed mechanisms for bacteriophage defense in lactic streptococci. FEMS Microbiol Lett 1987. [DOI: 10.1111/j.1574-6968.1987.tb02468.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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47
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Jarvis AW, Klaenhammer TR. Bacteriophage Resistance Plasmid pTR2030 Inhibits Lytic Infection of r
1
t Temperate Bacteriophage but Not Induction of r
1
t Prophage in
Streptococcus cremoris
R1. Appl Environ Microbiol 1987; 53:385-9. [PMID: 16347286 PMCID: PMC203670 DOI: 10.1128/aem.53.2.385-389.1987] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of pTR2030 on the replication of four small isometric bacteriophages were examined in
Streptococcus cremoris
R1. Three lytic phages (652, 720, and 751), which were isolated independently over a 29-year period, were unable to form plaques on a pTR2030 transconjugant of
S. cremoris
R1. The fourth phage evaluated, phage r
1
t, was a temperate phage induced from
S. cremoris
R1 by treatment with mitomycin C. A prophage-cured derivative of
S. cremoris
R1, designated R1Cs, was isolated and served as a lytic indicator for phage r
1
t. Strain R1Cs and a derivative of this strain that was relysogenized with r
1
t, designated R1Cs(r
1
t), were used as conjugal recipients for transfer of the phage resistance plasmid pTR2030. pTR2030 transconjugants of strains R1Cs and R1Cs(r
1
t) were evaluated for sensitivity to r
1
t phage and induction of r
1
t prophage, respectively. The temperate phage r
1
t adsorbed eficiently but did not form plaques on the prophage-cured, pTR2030 transconjugant strain T-R1Cs. However, in the r
1
t lysogen [T-R1Cs(r
1
t)], pTR2030 did not inhibit prophage induction with mitomycin C, cell lysis, or production of infective r
1
t phage particles. The data demonstrated that pTR2030-induced resistance inhibited lytic infection by r
1
t phage from without but did not retard lytic development after prophage induction within the cell. It was suggested that pTR2030-encoded phage resistance to small isometric phages may, therefore, act at the cell surface or membrane to prevent phage DNA passage into the host cell or inhibit early events required for lytic replication of externally infecting phage.
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Affiliation(s)
- A W Jarvis
- Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695-7624
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