• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.311-318
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• 2010

Antimicrobial finishing of textiles has been found to be an economical way to prevent (or treat) skin disorders. Hence, this research effort was aimed at elucidating the relationship between the molecular weight (MW) of chitosan and its antimicrobial activity upon six dermal reference microorganisms, as well as the influence of the interactions with cotton fabrics on said activity. Using 3 chitosans with different MWs, as well as two chitooligosaccharide (COS) mixtures, a relevant antimicrobial effect was observed by 24 h for the six microorganisms tested; it was apparent that the antimicrobial effect is strongly dependent on the type of target microorganism and on the MW of chitosan - being higher for lower MW in the case of E. coli, K. pneumoniae, and P. aeruginosa, and the reverse in the case of both Gram-positive bacteria. Furthermore, a strong antifungal effect was detectable upon C. albicans, resembling the action over Gram-positive bacteria. Interactions with cotton fabric resulted in a loss of COS activity when compared with cultured media, relative to the effect over Gram-negative bacteria. However, no significant differences for the efficacy of all the 5 compounds were observed by 4 h. The three chitosans possessed a higher antimicrobial activity when impregnated onto the fabric, and presented a similar effect on both Gram-positive bacteria and yeast, in either matrix. Pseudomonas aeruginosa showed to be the most resistant microorganism to all five compounds.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.24-29
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• 2018

The properties of concrete with addition of microgel - containing hydrogel support were investigated. As a result of measuring the slump of the self - healing concrete, the target slump was satisfied in all the mixing conditions, but the slump was decreased as the mixing amount of the hydrogel support increased. The change of porosity due to incorporation of hydrogel support was minimal. As a result of the evaluation of the compressive strength of the self - healing concrete, the incorporation of the hydrogel support did not affect the strength. However, under the same mixing condition, the dispersion value of the specimens tended to increase with increasing hydrogel support contents. As a result of the permeability test of self-healing concrete according to the incorporation of hydrogel support, it was confirmed that the mixing ratio of hydrogel support was effective to decrease the permeability coefficient.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.363-370
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• 2017

In this study, we stored frozen shrimp (Litopenaeus vannamei) at $4^{\circ}C$ during 12 days and investigated the effect of chitosan coating with natural preservatives (0.05% carvacrol, 0.05% thymol) on the growth of microorganism (mesophilic bacteria, psychrophilic bacteria, Pseudomonas spp., $H_2S$ producing bacteria) and physiological characteristics (total volatile basic nitrogen and pH) and sensory evaluation (appearance, odor and general acceptance). Chitosan coating with natural antimicrobial compounds (0.05% carvacrol and 0.05% thymol) had inhibited the growth of all the target microorganism and showed the significant antimicrobial activity (p < 0.05) to mesophilic bacteria, psychrophilic bacteria and $H_2S$ producing bacteria until 12 day (the last day of this study). These treated groups had showed the significant difference (p < 0.05) in total volatile basic nitrogen and all the sensory characteristics but not in pH. Therefore, chitosan coating combined with natural antimicrobial compounds (0.05% carvacrol and 0.05% thymol) showed the effective antimicrobial activity on major spoilage microorganism on shrimp and could be used to elongate the shelf life of refrigerated shrimp.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.510-518
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• 2021

Bacteriophages are considered excellent sensing elements for platforms detecting bacteria. However, their lytic cycle has restricted their efficacy. Here, we used the minor coat protein pIII domain (N1N2) of phage CTXφ to construct a novel surface plasmon resonance (SPR) biosensor that could detect Vibrio cholerae. N1N2 harboring the domains required for phage adsorption and entry was obtained from Escherichia coli using recombinant protein expression and purification. SDS-PAGE revealed an approximate size of 30 kDa for N1N2. Dot blot and transmission electron microscopy analyses revealed that the protein bound to the host V. cholerae but not to non-host E. coli K-12 cells. Next, we used amine-coupling to develop a novel recombinant N1N2 (rN1N2)-functionalized SPR biosensor by immobilizing rN1N2 proteins on gold substrates and using SPR to monitor the binding kinetics of the proteins with target bacteria. We observed rapid detection of V. cholerae in the range of approximately 10³ to 10⁹ CFU/ml but not of E. coli at any tested concentration, thereby confirming that the biosensor exhibited differential recognition and binding. The results indicate that the novel biosensor can rapidly monitor a target pathogenic microorganism in the environment and is very useful for monitoring food safety and facilitating early disease prevention.

• Korean Journal of Microbiology
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• v.49 no.3
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• pp.292-296
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• 2013

This study utilized an analysis method for detecting six microorganisms, such as Actinobacillus actinomycetemcomitans, Campylobacter rectus, Porphyromonas gingivalis, Tannerella forsythus, Treponema denticola, and Prevotella intermedia, triggering periodontal disease, using multiplex real-time polymerase chain reaction (PCR). The analysis including internal control was made by dividing the six species into two groups using four fluorescence dyes, and it was verified that there was no interference or cross-reaction between the target species and different kinds of oral microbial species. Qualitative and quantitative analyses were conducted on each microorganism in various samples, such as saliva and the plaque, using the multiplex real-time PCR and comparative analysis between periodontitis patients and healthy people, revealing obvious differences between them.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1229-1235
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• 2006

A lab-on-a-chip (LoC) was designed for simultaneous monitoring of microorganisms, antibiotic residues, somatic cells, and pH in raw milk. The LoC was fabricated from polydimethylsiloxane (PDMS) using microelectromechanical system (MEMS) technology, which consisted of two parts; a protein array and microchannel. The protein array was fabricated by immobilizing five types of antibodies corresponding to two microorganisms, two antibiotic residues, and somatic cells. A sol-gel film was deposited on a glass substrate to immobilize the antibodies. The target analytes in raw milk could be bound with the corresponding antibody by an immunoreaction, and the antigen-antibody complex was detected using fluorescence microscopy. SNARF-dextran was used as a pH indicator, and the SNARF-entrapped hydrogel was attached to the microchannel in the chip. After injecting the milk sample into the channel, the pH was measured by monitoring the change in fluorescence intensity by fluorescence microscopy. The on-chip simultaneous assay of two microorganisms (E. coli O157:H7 and Streptococcus agalactiae), two antibiotic residues (penicillin G and dihydrostreptomycin), and neutrophils was successfully accomplished using the proposed LoC system.

• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1680-1686
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• 2015

Inhibition of 4-nitroquinoline-1-oxide (4-NQO) genotoxicity by a probiotic strain of Lactobacillus rhamnosus (IMC501) was assessed by the prokaryotic short-term bioassay SOSChromotest, using Escherichia coli PQ37 as the target organism. Results showed the ability of strain IMC501 to rapidly and markedly counteract, in vitro, the DNA damage originated by the considered genotoxin. The inhibition was associated with a spectroscopic hypsochromic shift of the original 4-NQO profile and progressive absorbance increase of a new peak. IR-Raman and GC-MS analyses confirmed the disappearance of 4-NQO after contact with the microorganism, showing also the absence of any genotoxic molecule potentially available for metabolic activation (i.e., 4-hydroxyaminoquinoline-1-oxide and 4-nitrosoquinoline-1-oxide). Furthermore, we have shown the presence of the phenyl-quinoline and its isomers as major non-genotoxic conversion products, which led to the hypothesis of a possible pattern of molecular transformation. These findings increase knowledge on lactobacilli physiology and contribute to the further consideration of antigenotoxicity as a nonconventional functional property of particular probiotic strains.

• Fisheries and Aquatic Sciences
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• v.21 no.3
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• pp.8.1-8.6
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• 2018

Desmarestia japonica (Phaeophyceae, Desmarestiales) was recently established from the Japanese ligulate Desmarestia and is morphologically similar to D. ligulata. This species has been reported only from Japan. However, the taxonomic reports based on additional regional distributions are needed to clarify this taxonomic entity and its species boundaries. Because Desmarestia species have restricted distributions in Korea, we reexamined herbarium specimens of D. ligulata deposited at the National Institute of Biological Resources (South Korea). To improve the amplification efficiency of the polymerase chain reaction and avoid contamination by the DNA of other organisms, we developed taxon-specific molecular markers suitable for DNA barcoding of Desmarestia species. Nuclear ribosomal small subunit RNA (18S rDNA) and mitochondrial cytochrome c oxidase 1 (cox1) regions were selected as target DNA. As a result, both were successfully isolated from herbarium specimens of D. japonica acquired over 10 years. These molecular markers provide useful genetic information for herbarium specimens for which conventional molecular analysis is challenging.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1361-1369
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• 2023

Corynebacterium glutamicum (C. glutamicum) has been considered a very important and meaningful industrial microorganism for the production of amino acids worldwide. To produce amino acids, cells require nicotinamide adenine dinucleotide phosphate (NADPH), which is a biological reducing agent. The pentose phosphate pathway (PPP) can supply NADPH in cells via the 6-phosphogluconate dehydrogenase (6PGD) enzyme, which is an oxidoreductase that converts 6-phosphogluconate (6PG) to ribulose 5-phosphate (Ru5P), to produce NADPH. In this study, we identified the crystal structure of 6PGD_apo and 6PGD_NADP from C. glutamicum ATCC 13032 (Cg6PGD) and reported our biological research based on this structure. We identified the substrate binding site and co-factor binding site of Cg6PGD, which are crucial for understanding this enzyme. Based on the findings of our research, Cg6PGD is expected to be used as a NADPH resource in the food industry and as a drug target in the pharmaceutical industry.

• Food Science of Animal Resources
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• v.27 no.2
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• pp.222-227
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• 2007

In order to produce the antibody rich eggs against Salmonella gallinarum(S.G.) causing fowl typhoid, the productions of immunoglobulin in eggs were compared and examined with the feed additives, the variety of adjuvants in vaccines to layers, and the existence of additive antigens other than target microorganism. The examination of the average contents of specific IgY in immunized group by supplying hardwood charcoal showed that the group supplied with 0.5% hardwood charcoal had the highest contents, implying that the supply of hardwood charcoal promoted the production of specific IgY. Adjuvant appeared to have little effect on the average contents of total IgY, but specific IgY contents increased in the immunized group with Freund's adjuvant. Addition of BCG in adjuvant treatment increased specific IgY however, this feature was not seen in aluminum hydroxide treated group. Immunization at 15 week layers resulted in higher laying rate than immunization at 21 week and addition of hardwood charcoal in feed recovered laying rate. It was therefore, concluded that the feed supplement, such as hardwood charcoal followed by a proper immunization program concerning adjuvant, vaccination period and supplementary microorganism hastened the production of IgY.