• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.553-560
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• 1991

In the previous paper (10). a new temperate phage, Sigma FA1 had been isolated from B. circulans. Sigma FA1 had an icosahedral head with a diameter of about 70 nm, and a tail about 15 nm long, and beared a circularly permuted, linear duplex DNA. Signla FA1 killed sensitive cells by a single-hit process. Phage DNA injected into the cell immediately after infection was degraded slowly. Our results indicate that the killing action of Sigma FA1 is different from the phenomenon of abortive infection and suggest that the killing might be caused by a proteinaceous component of Sigma FA1.

• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.272-274
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• 2000

Temperate bacteriophage P2 has a nonessential gene called old(overcoming lysoginization defection). In the presence of old, the growth of the host (Escherichia coli) with recBC- genotype is ingibited, and another bacteriophage, lambda, cannot superinfect. The Old protein has been shown to possess an exonuclease actibity. Three mutant P2s(old 1, old 17, old 49) which did gene was coned into expression vectors to produce hexahistidine-tagged proteins. The proteins were affinity-purified and shown to lose its exonuclease activity on both double-stranded and single-stranded DNA substrates. Thus, it was concluded that the lambda exclusion was related to Old's exonuclease activity.

• Journal of fish pathology
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• v.11 no.2
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• pp.137-141
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• 1998

Temperate phages were effectively induced from presumptive lysogenized cells of 96 strains out of 111 strains of L. garvieae No. 44 strains (phage type B) as the host cell. Similar cultures in distilled water-based TSB did not induce lytic infection in these cells. These temperate phages were also effectively induced by ultraviolet irradiation. All phages isolated were lytic only to L. garvieae No. 44 strain and the lytic nature was different from those of PLgY, PLgW, and PLgS. The virions appeared extracellularly after 1h of induction culture and increased in number until reaching the maximum of $10^6$ PFU/ml after 12h. This phage production was lower than that ($10^{10}$ PFU/ml) of the virulent phage.

• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.457-463
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• 1999

The physical map of bacteriophage $\PhiFC1$ DNA was constructed with the restriction endonucleases SalI, BamHI, EcoRI, XbaI, and AvaI. The 40.5-kb DNA restriction map is shown to be circularly permuted representing the headful packaging mechanism of the phage. The DNA restriction fragments containing the packaging initiation site(pac) was localized on the restriction map and the nucleotide sequences of the region were analyzed. Four open reading frames (ORFs), following one another with the same orientation, were found at the region. The 2nd ORF (ORF-ts) has significant amino acid sequence homologies to the previously known terminase small subunits of other bacteriophages. The putative terminase small subunit gene has a presumptive NTP-hydrolysis motif and a helix-turn-helix motif. The cleavage site for the first round of packaging was found to be located at the coding sequence of the putative terminase small subunit gene. The fourth ORF, even if partially sequenced, has a good amino acid sequence homology to the portal vertex proteins of other bacteriophages representing the evolutionarily conserved arrangements of genes near the pac site of this bacteriophage, $\PhiFC1$.

• BMB Reports
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• v.29 no.5
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• pp.448-454
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• 1996

Bacteriophage ${\phi}FC1$ is a temperate phage which was identified as a prophage in the Enterococcus faecalis KBL703 chromosome. Phage ${\phi}FC1$ integrates into the host chromosome by site-specific recombination. The phage attachment site P (attP) was localized within the 0.65-kb XhoI-HindIII fragment and the nucleotide sequence of the region was determined. An open reading frame (mj1) which adjoined the phage attachment site encoded a deduced protein related to the site-specific recombinase family. The organization of this region was comparable to other site-specific recombination systems. The molecular weight of the expressed MJ1 in E. coli was in good agreement with the predicted 53,537 Da of the mj1 gene product. Elucidation of the phage-specific integration process in this study would provide useful genetic tools such as a chromosomal integration system.

• BMB Reports
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• v.40 no.2
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• pp.156-162
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• 2007

Two lysis-defective but DNA synthesis non-defective temperature-sensitive (ts) mutants of mycobacteriophage L1, L1G23ts23 and L1G25ts889 were found to be defective also in phage-specific RNA synthesis in the late period of their growth at 42$^{\circ}C$each to the extent of 50% of that at 32$^{\circ}C$The double mutant, L1G23ts23G25ts889 showed the ts defect in phage RNA synthesis that was nearly additive of those shown individually by the two single-mutant parents. Both G23 and G25 were shown to start functioning sometimes between 30 and 45 min after infection but the former gene might be dispensable after 45 min, while the latter was not. Northern analysis also shows that at 42$^{\circ}C$>, L1G23ts23 affects RNA synthesis more strongly than L1G25ts889 from L1 DNA segments that serve as the template for late gene transcription. Among the 21 virion and 12 non-virion late proteins synthesized by L1, L1G23ts23 is defective in the synthesis of at least 9 virion and all of non-virion proteins at 42$^{\circ}C$>. In contrast, L1G25ts889 is completely defective in synthesis of all the 33 late proteins. Possible roles of G23 and G25 in the positive regulation of transcription of different sets of late genes of L1 have been discussed.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.115-121
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• 1985

Five representative virulent phages (J1, TK93, K1, PD5, and CP1) and one temperate phage (.phi.1043) of Lactobacillus casei were compared to each other by analyzing the agarose gel electrophoretic patterns of restriction enzyme-digested phage DNAs. Nucleic acids of all the tested phages were double stranded DNA. DNAs of J1, TK93, K1, and ${\phi}$ 1043 phages had a size of about 42kb, but the size of PD5 and CP1 DNAs was avout 140kb. J1, TK93, K1, PD5, CP1, and ${\phi}$ 1043 DNAs were digested to 13, 13, 11, 14, 14, and 12 fragments by EcoR1, respectively, and showed its characteristec restriction patterns. Cohesive ends were present in J1, TK93, and ${\phi}$ 1043, but were absent in K1, PD5, and CP1. Restriction maps of J1 and TK93 DNAs showed nearly complete homology and their evolutionary relationship based upon the restriction analysis was discussed.

• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.1-11
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• 2001

Lactic acid bacteria (LAB) are widely used for various food fermentation. With the recent advances in modern biotechnology, a variety of bio-products with the high economic values have been produced using microorganisms. For molecular cloning and expression studies on the gene of interest, E. coli has been widely used mainly because vector systems are fully developed. Most plasmid vectors currently used for E, coli carry antibiotic-resistant markers. As it is generally believed that the antibiotic resistance markers are potentially transferred to other bacteria, application of the plasmid vectors carrying antibiotic resistance genes as selection markers should be avoided, especially for human consump-tion. By contrast, as LAB have some desirable traits such that the they are GRAS(generally recognized as safe), able to secrete gene products out of cell, and their low protease activities, they are regarded as an ideal organism for the genetic manipulation, including cloning and expression of homologous and heterologous genes. However, the vec-tor systems established for LAB are stil insufficient to over-produce gene products, stably, limiting the use of these organisms for industrial applications. For a past decade, the two popular plasmid vectors, pAM$\beta$1 of Streptococcus faecalis and pGK12 theB. subtilis-E. coli shuttle vector derived from pWV01 of Lactococcus lactis ssp. cremoris wg 2, were most widely used to construct efficient chimeric vectors to be stably maintained in many industrial strains of LAB. Currently, non-antibiotic markers such as nisin resistance($Nis^{r}$ ) are explored for selecting recombi-nant clone. In addition, a gene encoding S-layer protein, slp/A, on bacterial cell wall was successfully recombined with the proper LAB vectors LAB vectors for excretion of the heterologous gene product from LAB Many food-grade host vec-tor systems were successfully developed, which allowed stable integration of multiple plasmid copies in the vec-mosome of LAB. More recently, an integration vector system based on the site-specific integration apparatus of temperate lactococcal bacteriophage, containing the integrase gene(int) and phage attachment site(attP), was pub-lished. In conclusion, when various vector system, which are maintain stably and expressed strongly in LAB, are developed, lost of such food products as enzymes, pharmaceuticals, bioactive food ingredients for human consump-tion would be produced at a full scale in LAB.