• Microbiology and Biotechnology Letters
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• v.10 no.3
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• pp.217-222
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• 1982

A lactic starter organism, Lactobaciilus casei YIT 9018 was treated with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) to obtain phage-resistant mutants. Freshly grown cells suspended in citrate buffer were exposed to NTG of 50 g/$m\ell$ for 40 min. Among 88 colonies isolated eight colonies showed distinct resistance to phages isolated previously from milk plants. The eight new colonies showed character similar to the original L. casei except that they responded differently to phage of different sources and thus were designated as eight different mutants of L casei. From the phage resisting toaether with the fermentative ability equivalent to the mother organism the mutants may be considered to be used as starter cultures for fermented milk.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.87-94
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• 2018

This study investigated the feasibility of the lytic, tailed Bacillus cereus-specific phage for use in a ferromagnetoelastic (FME) biosensor as a novel recognition element. The phage was immobilized at various concentrations through either direct adsorption or a combination of 11-mercapto-1-undecanoic acid (11-MUA) and [N-(3-dimethylaminopropyl)-N'-carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS)]. The effects of time and temperature on its lytic properties were investigated through the exposure of B. cereus (4 and 8 logCFU/ml) to the phage (8 logPFU/ml) for various incubation periods at $22^{\circ}C$ and at various temperatures for 30 and 60 min. As the phage concentration increased, both immobilization methods also significantly increased the phage density (p < 0.05). SEM images confirmed that the phage density on the FME platform corresponded to the increased phage concentration. As the combination of 11-MUA and EDC/NHS enhanced the phage density and orientation by up to 4.3-fold, it was selected for use. When various incubation was conducted, no significant differences were observed in the survival rate of B. cereus within 30 min, which was in contrast to the significant decreases observed at 45 and 60 min (p < 0.05). In addition, temperature exerted no significant effects on the survival rate across the entire temperature range. This study demonstrated the feasibility of the lytic, tailed B. cereus-specific phage as a novel recognition element for use in an FME biosensor. Thus, the phage could be placed on the surface of foods for at least 30 min without any significant loss of B. cereus, as a result of the inherent lytic activity of the B. cereus-specific phage as a novel recognition element.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.184-188
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• 1987

Evidences that the mannose permease of Escherichia coli mediates the infection of N4 in early steps, were obtained as follows. First, A mutant strain of Escherichia coli which was resistant to both wild type N4 and lambda whose genome is Charon 4A containing human genomic fragments in its EcoR I site, could not use mannose efficiently. Second, N4 could not infect pel mutant strains which lack one or all of intact components of mannose permease. However, unknown alterations in N4 made it possible for the phage to infect pel mutant of E. coli. It also turned out to be clear that the receptor of N4 was different from that of lambda.

• Food Science and Preservation
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• v.15 no.5
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• pp.617-621
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• 2008

Sequential passes through $Sephadex^{TM}$ columns were used to select phages that displays ligands for dextran ($\alpha$-1,6 linked linear chains) from a phage antibody library. Those phages that bound to the $Sephadex^{TM}$ in each iteration were replicated in E. coli. A phage preparation isolated on the third round selection produced 5.4 nephelos turbidity units (NTU) in a dextran specific immunonephelometric assay, a 2.2 fold higher value than the phage preparation from the first round selection. This phage gave $72\;{\pm}\;10$ normalized intensity (N.I.) in a dip-stick assay against high molecular size dextran (T2000, $2\;{\times}\;10^6) and significantly lower color ($30\;{\pm}\;6$ N.I.) against low molecular size dextran (T10, $10^4$). The presence of an Fab insert in each of these phages was confirmed using a $\beta-galactosidase linked assay and polymerase chain reaction.

• Interdisciplinary Bio Central
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• v.4 no.3
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• pp.9.1-9.7
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• 2012

Filamentous phages have been in the limelight as a new type of nanomaterial. In this study, genetically and chemically modified fd phage was used to generate a biomimetic phage self-assembly product. Positively charged fd phage (p8-SSG) was engineered by conjugating 3-aminopropyltriethoxysilane (APTES) to hydroxyl groups of two serine amino acid residues introduced at the N-terminus of major coat protein, p8. In particular, formation of a phage network was controlled by changing mixed ratios between wild type fd phage and APTES conjugated fd-SSG phage. Assembled phages showed unique bundle and network like structures. The bacteriophage based self-assembly approach illustrated in this study might contribute to the design of three dimensional microporous structures. In this work, we demonstrated that the positively charged APTES conjugated fd-SSG phages can assemble into microstructures when they are exposed to negatively charged wild-type fd phages through electrostatic interaction. In summary, since we can control the phage self-assembly process in order to obtain bundle or network like structures and since they can be functionalized by means of chemical or genetic modifications, bacteriophages are good candidates for use as bio-compatible scaffolds. Such new type of phage-based artificial 3D architectures can be applied in tuning of cellular structures and functions for tissue engineering studies.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.129-137
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• 1985

The RK-temperate phage which infected with Bacillus cereus was isolated and the characters were investigated. The induction of RK-temperate phage from host bacterium attained by ultraviolet light irradiation (15W, 30cm, 30-120sec) and mitomycin C treatment (0.2-2 ug/ml). The host range of RK-temperate phage was not revealed with lysogenic and related strains of B. cereus. But B. cereus(PS) 352 which obtained by N-nitrosoguanidine treatment (1,000{$\mu}g/ml)$ to phage infected with host bacteria was sensitive bacteria of RK-temperate phage. RK-temperate phage was stabilized at the condition of nutrient broth (pH 7-8), Tris-buffer (pH 7-8) and ammonium buffer (pH 8-9) and Sorensen's phosphate buffer (pH 6-7), but unstabilized at other salt solutions and pH range. Also, thermostability was to $45^{\circ}C$ but unstabilized at above $50^{\circ}C$. At RK-temperate phage, the measurment values of head, neck, mid tail and end tail were 59nm, $9{\times}16nm,\;10{\times}189nm,\;and\;10{\times}14nm$ respectively. The morphology of head was regular polyhedron, and the end tail was coneate form. On the one hand, the number of capsid protein layer of tail were consist of 4, 35, and 1 at neck, mid tail, and end tail, respectively. RK-temperate phage was identified with DNA phage and G+C contents were 38.63. The latent time of RK-temperate phage was 30 minutes and the burst size was 70-80. And the host bacteria was lysed in case of multi-infection, above moi 1.

• Korean Journal of Microbiology
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• v.16 no.2
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• pp.79-89
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• 1978

The RK-temperate phage which infected with Bacillus cereus was isolated and the characters were investigated. The induction of RK-temperate phage from host bacterium attained by ultraviolet light irradiation (15W, 30cm, 30-120sec) and mitomycin C treatment (0.2-2 ug/ml). The host range of RK-temperate phage was not revealed with lysogenic and related strains of B. cereus. But B. cereus(PS) 352 which obtained by N-nitrosoguanidine treatment(1,000.$\mu$g/ml) to phage infected with host bacteria was sensitive bacteria of RK-temperate phage. RK-temperate phage was stabilized at the condition of nutrient broth (pH 7-8), Tris-buffer (pH 7-8) and ammonium buffer (pH 8-9) and Sorensen's phosphate buffer (pH 6-7), but unstabilized at other salt solutions and pH range. Also, thermostability was to 45.deg.C but unstabilized at above 50.deg.C. At RK-temperate phage, the measurment values of head, neck, mid tail and end tail were 59nm, 9*16nm, 10*189nm, and 10*14nm respectively. The morphology of head was regular polyhedron, and the end tail was coneate form. On the one hand, the number of capsid protein layer of tail were consist of 4, 35, and 1 at neck, mid tail, and end tail, respectively. RK-temperate phage was identified with DNA phage and G+C contents were 38.63. The latent time of RK-temperate phage was 30 minutes and the burst size was 70-80. And the host bacteria was lysed in case of multi-infection, above moi 1.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.215-220
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• 1990

Prophage cured strain derivatives from Luctobacillirs araei YIT 9018 were isolated from thermoinducible mutant of the parent lysogenic strain. Two thermoinducible mutants were isolated from L. casei YIT 9018 strain treated with N-methyl-N'-nitro-N-nitrosoguanidine. Prophage cured strains were selected after heat induction of thermoinducible strains at $42^{\circ}C$ for 30 min in MRT medium containing anti- 4 FSV serum. The prophage cured strains, L. casei HYM 1213 and L. casei HYM 4024, could be used an indicator strain for temperate phage $\phi$ FSW. The growth, lactic acid producing ability and carbohydrates fermentation of L. casei HYM 1213 were similar to the parent L. cmei YIT 9018 strain, but A. casei HYM 4024 was not. One of the prophage cured strain, L. cmei HYM 1213, could be used industrially .to produce lactic acid beverages because this strah could not induce the virulent phage$\phi$FSV. The physiological characterization of L. casei HYM 1213 strain was similar to the parent L. casei YIT 9018 strain.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.290-295
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• 1991

N4 phage, which infects E. coli K-12 strains, could not infect E. coli K-12 strains containing rtn(resistant to N4) gene on plasmids, which was isolated from Proteus vulgaris ATCC 13315. The region of rtn gene for Rtn phenotype was reduced to the 1.7 kb HincII-AccI fragment, and rtn gene seemed to have its own promoter. This putative promoter was present in 107 bp HindII-DraI fragment, and known to be functional in E. cole K-12, which is supported by the fact that phenotype of a subclone, pRMG103A1B which does not contain the 107 bp fragment, was dependent on the existance of a functional promoter in the upstream of rtn gene, and that the 107 bp fragment had promoter activity when located in the upstream of structural gene of galactodinase of E. coli. The promoter-bearing fragment contains two overlapping putative promoter sequences, both of which show a fit in eight of twelve nucleotides with consensus sequences of E. coli promoters at the -35 and -10 regions.

• BMB Reports
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• v.28 no.4
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• pp.336-341
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• 1995

Using a mutant M13 phage derivative lacking a great part of the complementary strand synthesis origin, we identified six single-strand initiation (ssi) signals for DNA replication in pACYC184, pLG214, pGKV21, and pDPT270 plasmids, and named them $ssiA_{YC}$, $ssiA_{LG}$, $ssiB_{LG}$, $ssiA_{KV}$, $ssiA_{PT}$, and $ssiB_{PT}$, respectively. Two of them were from pDPT270, one from downstream the on of pACYC184, two from pLG214, one from upstream the plus origin of pGKV21. Introduction of these ssi signals into the deleted $ori_c$ site of a mutant filamentous M13 phage ($M13{\Delta}lac182$) resulted in the restoration of growth activity of this phage. These ssi signals were classified into a number of groups on the basis of sequence similarity. $ssiA_{YC}$ and $ssiA_{LG}$ show extensive sequence homology to the n'-site (primosome assembly sites) of ColE1, whereas $ssiB_{PT}$ is homologous to the n'-site of ${\Phi}X174$. $ssiA_{PT}$ belongs to G4-type ssi signals which require only dnaG primase and SSB protein for the priming of replication. In addition, possible biological roles of these ssi signals are discussed.