• Microbiology and Biotechnology Letters
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• v.27 no.5
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• pp.415-418
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• 1999

Thecodiplosis japonensis is an important insect pest in pine trees and hard to be controlled by chemical pesticides due to its characteristic life cycle. Experiments were conducted to determine the pathogenicity and growth temperature of several entomopathogenic fungi as potential microbial insectcides for T. japonensis. Beauveria bassiana SFB-SC and Paecilomyces fumosoroseus SFP-198 were highly pathogenic against T. japonensis. B. bassiana SFB-SC had also pathogenicity against a beneficial insect Bombyx mori. Growth rate and pathogenicity of P. funmosoroseus SFP-198 under 15$^{\circ}C$ was higher than those of B. bassians SFB-SC. These results indicated that P. fumosoroseus SFP-198 is a potential microbial control candidate for control of T. japonensis.

• Archives of Pharmacal Research
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• v.28 no.9
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• pp.1031-1036
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• 2005

[ $(+)-Lyoniresinol-3{\alpha}-O-\beta-D-glucopyranoside$ ] (1) was isolated from an ethyl acetate extract of the root bark from Lycium chinense Miller, and its structure was determined using 1D and 2D NMR spectroscopy including DEPT, HMQC, and HMBC. $(+)-Lyoniresinol-3{\alpha}-O-\beta-D-glucopyranoside$ exhibited potent antimicrobial activity against antibiotic-resistant bacterial strains, methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients, and human pathogenic fungi without having any hemolytic effect on human erythrocytes. In particular, compound 1 induced the accumulation of intracellular trehalose on C. albicans as stress response to the drug, and disrupted the dimorphic transition that forms pseudo-hyphae caused by the pathogenesis. This indicates that $(+)-Lyoniresinol-3{\alpha}-O-\beta-D-glucopyranoside$ has excellent potential as a lead compound for the development of antibiotic agents.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.48-55
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• 2004

Six strains of an obligate predatory bdellovibrio isolate that preys on Burkholderia glumae in rice paddy field water and rhizosphere soil, were identified and characterized. The numbers of Bdellovibrio cells varied from $3.2{\times}10^3$ to $9.2{\times}10^3$ plaque-forming unit/g after enrichment in cells of B. glumae. Prey range tests with six Bdellovibrio strains and 17 prey strains of rice-pathogenic, antibiosis-related, or nitrogen-fixing bacteria resulted in unique predation patterns in related prey cells. Strain BG282 had the widest prey range on 7 plant pathogenic bacteria among the 17 prey strains tested. However, no predation occurred with strains of Azospirillum brasilense, Paenibacillus polymyxa, Pseudomonas fluorescens, P. putida, and Serratia marcescens that are associated with antibiosis or nitrogen fixation in the rice ecosystem. Identification was confirmed by the presence of typical bdelloplast in the prey cells of B. glumae and by a PCR assay using B. bacteriovorus-specific primers. Furthermore, 16S rDNA sequencing of the six bdellovibrio strains showed a homology range of 97.2% to 99.2% to the type strain of B. bacteriovorus.

• Journal of Microbiology and Biotechnology
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• v.21 no.3
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• pp.229-235
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• 2011

Antimicrobial peptides exhibit high levels of antimicrobial activity against a broad range of spoilage and pathogenic microorganisms. Compared with bacteriocins produced by lactic acid bacteria, antimicrobial peptides from the genus Bacillus have been relatively less recognized despite their broad antimicrobial spectra. These peptides can be classified into two different groups based on whether they are ribosomally (bacteriocins) or nonribosomally (polymyxins and iturins) synthesized. Because of their broad spectra and high activity, antimicrobial peptides from Bacillus spp. may have great potential for applications in the food, agricultural, and pharmaceutical industries to prevent or control spoilage and pathogenic microorganisms. In this review, we introduce ribosomally synthesized antimicrobial peptides, the lantibiotic bacteriocins produced by members of Bacillus. In addition, the biosynthesis, genetic organization, mode of action, and regulation of subtilin, a well-investigated lantibiotic from Bacillus subtilis, are discussed.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.354-358
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• 2014

A screening test showed that lycorine exhibited significant antifungal activity against 24 pathogenic crop fungi at concentrations of 500 ${\mu}g/ml$ and 100 ${\mu}g/ml$, respectively. Fusarium graminearum was selected for antifungal mechanism studies by observing its mycelial morphology and investigating the variations in its conductivity. In addition, the substance absorption and metabolism of F. graminearum were explored. The mechanism was revealed as being one by which lycorine destroyed the cellular membrane and further influenced substance absorption and cell metabolism.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1996.06a
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• pp.3-7
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• 1996

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.41-48
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• 1984

The present study was undertaken to elucidate the antibacterial spectrum of L. casei phage type $J_1$ strain isolated from a fermented milk product against pathogenic enteric bacteria. Growth inhibitory effects and minimum inhibitory concentration(MIC) of culture supernatants of L. casei grown in MRS broth were measured by both plate culture method and microplate broth dilution technique against Salmonella typhi, Salmonella typhimurium, Shigella flexneri, Shigella dysenteriae, enterpathogenic E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The results are summarized as follows: 1. The MRS broth culture of L. casei gave a similar extent of growth inhibitory effects against S. typhi, S. typhimurium, S. flexneri, S. dysenteriae, E. coli, K. pneumoniae and P. aeruginosa, respectively. 2. The inhibitory effects of L. casei culture were observed either in whole broth culture or in culture supernatant, but neither the bacterial suspension nor the neutralized culture supernatant showed such as antibacterial activities. 3. The MIC titres of the culture supernatants were ${\log_2}5$ to ${\log_2}6$, whereas those of the neutralized culture supernatant dropped markdely to ${\log_2}2$ to ${\log_2}3$. These results indicated that major portion of growth inhibitory effects of MRS broth culture of L. casei against enteric bacterial pathogens was possibly due to the acids produced, and minor portion to other antibacterial substances.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.155-162
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• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1060-1067
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• 2006

This study was undertaken to determine the effect of reservoirs on water quality and the distribution of pathogenic and indicator bacteria in a drinking water distribution system (total length 14km). Raw water, disinfected water, and water samples from the distribution system were subjected to physicochemical and microbiological analyses. Most factors encountered at each season included residual chloride, nitrate, turbidity, and phosphorus for heterotrophic bacterial distribution, and hardness, heterotrophic bacteria, sampling site, and DOC (dissolved organic carbon) for bacteria on selective media. No Salmonella or Shigella spp. were detected, but many colonies of opportunistic pathogens were found. Comparing tap water samples taken at similar distances from the water treatment plant, samples that had passed through a reservoir had a higher concentration of heterotrophic bacteria, and a higher rate of colony formation with 10 times as many bacteria on selective media. Based on the results with m-Endo agar, the water in reservoirs appeared safe; however, coliforms and opportunistic pathogenic bacteria such as Pseudomonas aeruginosa were identified on other selective media. This study illustrates that storage reservoirs in the drinking water distribution system have low microbiological water quality by opportunistic pathogens, and therefore, water quality must be controlled.

• Journal of Microbiology and Biotechnology
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• v.2 no.3
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• pp.209-214
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• 1992

Serratia marcescens co-cultured with various phytopathogenic fungi, including Rhizopus stolonifer, Helminthosporium allii, Pyricularia oryzae, Fusarium oxysporium and Collectothricom cassiicola, in an LB- agar medium containing 1.5% swollen chitin, significantly inhibitied fungal growth. Fungal hyphae grew rapidly outward from the culture dish center, but the hyphal extensions of the pathogenic fungi were significantly inhibited in a perimetric contact area with S. marcescens. This was especially evident in pathogenic fungi which have a high chitin content in their cell walls. The extracellular chitinase activities of S. marcescens were increased seven fold by the addition of 1.5% swollen chitin to the LB-broth, compared to chitinase activities in a culture medium without chitin. The type of induction was dependent on the various forms of chitin used. When the culture supernatant of S. marcescens or the chitinases of Streptomyces griceus purchased from Sigma Chemical Co., were incubated with the mycelium of F. oxysporium, the mycelium gradually burst as cultivation time progressed and completely lysed after incubation for 2 days. On the other hand, E. coli extract did not hydrolyze the F. oxysporium mycelium at all. These data showed that the chitinolytic activities of S. marcescens play important roles in the biochemical control of phytopathogenic fungi.