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1.
Food Microbiol ; 110: 104163, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36462819

ABSTRACT

This study aimed to investigate the microbiota in raw milk and the influence of storage temperature on the microbiota shift after biofilm formation. Raw milk stored at 4 °C and biofilms developed in raw milk incubated at 4 °C or 25 °C for 7 days were subjected to microbiota analysis as well as quantitative analyses of aerobic or anaerobic bacteria. The levels of aerobic bacteria increased during biofilm formation, while no significant changes were observed within anaerobic bacteria. In addition, there was a difference between aerobic and anaerobic bacterial counts in raw milk and biofilm stored for 7 days. The pattern of microbial composition differed by temperature. In addition, the genus Pseudomonas (53-71%) occupied a high proportion in raw milk, and the raw milk biofilm developed at 4 °C, while the genus Lactobacillus (75-83%) was predominant in biofilms developed at 25 °C. Intriguingly, bacterial richness was higher in raw milk on day 0 and biofilm developed at 4 °C than raw milk after 7 days of storage at 4 °C. These findings suggest that temperature critically affects the bacterial composition of both raw milk and its associated biofilm.


Subject(s)
Microbiota , Stainless Steel , Animals , Temperature , Milk , Biofilms
2.
Food Microbiol ; 109: 104119, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36309431

ABSTRACT

Photocatalysts, including titanium dioxide (TiO2), have attracted much attention in food safety for controlling foodborne pathogens. However, the study of the photocatalytic activity on various food-surrounding media and the factors that affect the efficacy of photocatalytic inactivation is incomplete. In this study, to inactivate foodborne pathogens in food-surrounding environments, TiO2-based photocatalysts with ultraviolet A (UVA, 365 nm) and visible light (VIS, 405 nm) were employed. Three TiO2-based photocatalysts, namely, Degussa P25 TiO2, carbon-modified KRONOClean 7000® (C-TiO2), and Pt-doped Ishihara-Sangyo MPT-623 (Pt-TiO2) inactivated Staphylococcus aureus and Escherichia coli O157:H7 exposed to UVA and VIS light in both water and air samples. Among them, Degussa P25 under UVA showed the highest bactericidal effects in both water and air treatments, which induced 5.19 log reductions in S. aureus when treated for 11.68 J/cm2, and E. coli O157:H7 was reduced by more than 6.21 log for 1.32 J/cm2 in the water sample. For air treatment, the combination of Degussa P25 and UVA achieved 3.45 and 3.28 log reductions for Staphylococcus aureus and E. coli O157:H7, respectively, in a developed laboratory-scale chamber for 1 h and 20.02 J/cm2. Scavenger assays showed that regardless of the photocatalyst and wavelength used, reactive oxygen species (ROS) generation causes cell membrane disruption of foodborne pathogens. However, the types of ROS that are generated vary among the photocatalysts and are related to different bactericidal efficacies. These results indicated that TiO2-based photocatalytic activity can be used to control microbiological hazards in various environments in the food industry.


Subject(s)
Escherichia coli O157 , Staphylococcal Infections , Humans , Staphylococcus aureus , Reactive Oxygen Species , Anti-Bacterial Agents/pharmacology , Water/pharmacology , Cell Membrane , Colony Count, Microbial
3.
Food Microbiol ; 116: 104350, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37689424

ABSTRACT

In the present study, the characteristics of Staphylococcus aureus biofilms matured in tryptic soy broth (TSB), low-fat milk, or whole milk samples were identified along with their resistance to 405 nm light with or without folic acid. Phenotypic properties of carbohydrate and protein contents in extracellular polymeric substance (EPS) of S. aureus biofilms matured in different conditions were identified. The carbohydrate content was higher in the biofilm matured in low-fat milk (1.27) than the samples matured in whole milk (0.58) and TSB (0.10). Protein content in the EPS of biofilm was higher in the sample matured in whole milk (6.59) than the samples matured in low-fat milk (3.24) and TSB (2.08). Moreover, the maturation condition had a significant effect on the membrane lipid composition of the biofilm, producing more unsaturated fatty acids in biofilm matured in milk samples. These changes in biofilm matured in milk samples increased the resistance of S. aureus to 405 nm light in the presence of folic acid (LFA). Additionally, transcriptomic analysis was conducted to identify the response of S. aureus biofilm to LFA treatment. Several genes related to DNA and protein protection from oxidative stress along with biofilm accumulation were overexpressed in the LFA-treated biofilms. These results indicate the maturation of S. aureus biofilm in various samples and the biofilms responses to bactericidal treatments.


Subject(s)
Staphylococcal Infections , Staphylococcus aureus , Humans , Animals , Staphylococcus aureus/genetics , Extracellular Polymeric Substance Matrix , Milk , Folic Acid/pharmacology , Biofilms
4.
Food Microbiol ; 114: 104274, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37290863

ABSTRACT

This study aimed to investigate the microbiota in the air and on the surface of a refrigerator and to inactivate aerosolized Staphylococcus aureus using a TiO2-UVLED module. A total of 100 L of the air and 5000 cm2 surfaces in seven household refrigerators were collected using an air sampler and a swab, respectively. Samples were subjected to microbiota analysis as well as quantitative analyses of aerobic or anaerobic bacteria. The level of airborne aerobic bacteria was 4.26 log CFU/vol (100 L), while that of surface aerobic bacteria was 5.27 log CFU/surface (5000 cm2). PCoA based on the Bray-Curtis metric revealed that the bacterial composition differed between samples collected from refrigerators with and without a vegetable drawer. Moreover, pathogenic bacteria containing genera and order from each sample were found, such as Enterobacaterales, Pseudomonas, Staphylococcus, Listeria, and Bacillus. Among them, Staphylococcus aureus was determined to be a core hazardous pathogen in air. Therefore, three S. aureus strains isolated from the air in refrigerators, as well as a reference strain of S. aureus (ATCC 6538P), were inactivated by a TiO2-UVLED module in a 512 L aerobiology chamber. All aerosolized S. aureus were reduced over 1.6 log CFU/vol after treatment with TiO2 under UVA (365 nm) light at 40 J/cm2. These findings suggest that TiO2-UVLED modules have the potential to be used to control airborne bacteria in household refrigerators.


Subject(s)
Bacteria , Staphylococcus aureus , Titanium/pharmacology
5.
Plant Dis ; 2023 May 16.
Article in English | MEDLINE | ID: mdl-37194209

ABSTRACT

Tulip cultivation in Korea primarily uses imported bulbs due to the absence of domestic production. To ensure safety and sustainability, Korean authorities have implemented strict phytosanitary measures for five viruses: arabis mosaic virus, tobacco necrosis virus, tobacco ringspot virus, tomato black ring virus, and tomato bushy stunt virus. In April 2021, 86 tulip plants presented symptoms such as chlorotic mottle, mosaic, streak, stripe, yellowing of the leaves, and color breaking on flowers. These samples were collected to investigate the incidence of viruses in four Korean provinces (Gangwon, Gyeongbuk, Gyeongnam, and Chungnam). The leaves and petals from each individual sample (10 mg each) were pooled and ground using liquid nitrogen. Total RNA was extracted using a Maxwell® 16 LEV Plant RNA Kit (Promega, Madison, USA). A cDNA library was constructed using TruSeq Standard Total RNA with Ribo - Zero (Illumina, San Diego, USA) and sequenced on an Illumina NovaSeq 6000 platform (Macrogen, Seoul, Korea) with 100-bp paired-end reads. Trinity software identified tulip breaking virus (TBV), tulip virus X (TVX), and lily symptomless virus (LSV), which are known to occur in Korea (Bak et al. 2023) by de novo assembly of 628 million reads into 498,795 contigs. The contigs were annotated as previously described (Bak et al. 2022). Moreover, a contig (ON758350) related to olive mild mosaic virus (OMMV; genus Alphanecrovirus, family Tombusviridae) was identified through BLASTn analysis. This contig had a 99.27% nucleotide (nt) identity to OMMV PPO-L190209 (KU641010), which was assembled from 201,346 reads and spanned 3,713 bp. To confirm the presence of OMMV, a primer pair (5'-GAATGTCTGGCGTTAAGCG-3'/5'-GTGTCCTGCGCATCATACAC-3') was designed to amplify a 797-bp fragment of the coat protein gene. In RT-PCR, 31.4% (27/86) of samples were positive for OMMV and coinfected with TBV or TBV+LSV. Coinfection with TBV led to chlorotic mottling and stripes, whereas triple coinfection with TBV+LSV produced distinct yellow streaks and mosaic within the lesion boundaries. In contrast, solely TBV infection did not produce such symptoms. The samples infected with OMMV were exclusively collected from Gangwon and Gyeongnam. In each province, an RT-PCR amplicon was cloned, and subsequently sequenced (Bioneer, Daejeon, Korea). The obtained sequences were named CC (OM243091) and GS (OM243092), and they shared 98.6% and 98.9% identity with PPO-L190209 (KU641010), respectively. A bioassay was conducted using a leaf infected with OMMV CC and TBV to inoculate 13 indicator species in triplicate, including Capsicum annuum, Chenopodium amaranticolor, C. quinoa, Cucumis sativus, Nicotiana benthamiana, N. clevelandii, N. glutinosa, N. occidentalis, N. rustica, N. tabacum, Solanum lycopersicum, Tetragonia tetragonioides, and Tulipa gesneriana. The RT-PCR revealed positivity only for OMMV in the upper leaves of N. clevelandii, while all other species were negative with no symptoms. To our knowledge, this is the first report of OMMV occurring in tulips grown from imported bulbs in Korea, with no other known natural hosts such as olive tree (Cardoso et al. 2004), spinach (Gratsia et al. 2012), and corn salad (Verdin et al. 2018). The Korean OMMV isolates exhibited a high nt identity with the foreign isolate, and the samples were collected from farms that rely entirely on bulb imports for cultivation. These suggest that the outbreak of OMMV was likely caused by imported bulbs.

6.
Int J Mol Sci ; 24(7)2023 Mar 30.
Article in English | MEDLINE | ID: mdl-37047447

ABSTRACT

Cancer is a major disease and the leading cause of death worldwide, with colorectal cancer (CRC) being the third-most common cancer in Korea. The survival rate associated with CRC reduces as the disease stage increases. Therefore, its early detection and treatment can greatly increase patient survival rates. In this study, we identified the tetraspanin 5 (TSPAN5) gene as an important biomarker for predicting the prognosis of patients with CRC. A TMA slide was used for statistical analysis. pN and clinical stage were found to be significant factors according to chi-square analysis, whereas pT, pN, metastasis, clinical stage, and TSPAN5 expression were significant according to Cox regression analysis. In order to prove the usefulness of TSPAN5, which is overexpressed in patients with metastatic CRC, as a biomarker, proliferation, migration, invasion, and tumorigenicity were examined using cell lines inhibited using small interfering RNA. The evaluations confirmed that TSPAN5 suppression, in turn, suppressed proliferation, migration, invasion, and tumorigenesis, which are characteristic of cancer cells. Therefore, the evaluation of TSPAN5 expression may help observe the prognosis of CRC and determine an appropriate treatment method for patients with CRC.


Subject(s)
Colorectal Neoplasms , Humans , Cell Line, Tumor , Prognosis , Cell Movement/genetics , Colorectal Neoplasms/diagnosis , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Tetraspanins/genetics , Tetraspanins/metabolism , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism
7.
Int J Mol Sci ; 24(23)2023 Nov 24.
Article in English | MEDLINE | ID: mdl-38069026

ABSTRACT

Colorectal cancer (CRC) is one of the most common and deadly cancers in the world. However, no effective treatment for the disease has yet been found. For this reason, several studies are being carried out on the treatment of CRC. Currently, there is limited understanding of the role of CPNE7 (copine-7) in CRC progression and metastasis. The results of this study show that CPNE7 exerts an oncogenic effect in CRC. First, CPNE7 was shown to be significantly up-regulated in CRC patient tissues and CRC cell lines compared to normal tissues according to IHC staining, qRT-PCR, and western blotting. Next, this study used both systems of siRNA and shRNA to suppress CPNE7 gene expression to check the CPNE7 mechanism in CRC. The suppressed CPNE7 significantly inhibited the growth of CRC cells in in vitro experiments, including migration, invasion, and semisolid agar colony-forming assay. Moreover, the modified expression of CPNE7 led to a decrease in the levels of genes associated with epithelial-mesenchymal transition (EMT). The epithelial genes E-cadherin (CDH1) and Collagen A1 were upregulated, and the levels of mesenchymal genes such as N-cadherin (CDH2), ZEB1, ZEB2, and SNAIL (SNAL1) were downregulated after CPNE7 inhibition. This study suggests that CPNE7 may serve as a potential diagnostic biomarker for CRC patients.


Subject(s)
Colorectal Neoplasms , Signal Transduction , Humans , Cell Line, Tumor , Cell Movement/genetics , Cell Proliferation/genetics , Colorectal Neoplasms/pathology , Epithelial-Mesenchymal Transition/genetics , Gene Expression Regulation, Neoplastic , Neoplasm Metastasis , RNA, Small Interfering/genetics
8.
New Phytol ; 235(2): 743-758, 2022 07.
Article in English | MEDLINE | ID: mdl-35403705

ABSTRACT

Hybridization and polyploidization are pivotal to plant evolution. Genetic crosses between distantly related species are rare in nature due to reproductive barriers but how such hurdles can be overcome is largely unknown. Here we report the hybrid genome structure of xBrassicoraphanus, a synthetic allotetraploid of Brassica rapa and Raphanus sativus. We performed cytogenetic analysis and de novo genome assembly to examine chromosome behaviors and genome integrity in the hybrid. Transcriptome analysis was conducted to investigate expression of duplicated genes in conjunction with epigenome analysis to address whether genome admixture entails epigenetic reconfiguration. Allotetraploid xBrassicoraphanus retains both parental chromosomes without genome rearrangement. Meiotic synapsis formation and chromosome exchange are avoided between nonhomologous progenitor chromosomes. Reconfiguration of transcription network occurs, and less divergent cis-elements of duplicated genes are associated with convergent expression. Genome-wide DNA methylation asymmetry between progenitors is largely maintained but, notably, B. rapa-originated transposable elements are transcriptionally silenced in xBrassicoraphanus through gain of DNA methylation. Our results demonstrate that hybrid genome stabilization and transcription compatibility necessitate epigenome landscape adjustment and rewiring of cis-trans interactions. Overall, this study suggests that a certain extent of genome divergence facilitates hybridization across species, which may explain the great diversification and expansion of angiosperms during evolution.


Subject(s)
Brassicaceae , Genome, Plant , Brassicaceae/genetics , DNA Methylation/genetics , Hybridization, Genetic
9.
J Appl Microbiol ; 132(1): 290-297, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34310828

ABSTRACT

AIMS: In this study, the efficacy of using vacuumed hydrogen peroxide vapour (VHPV) to inactivate foodborne pathogens in whole dried black pepper (Piper nigrum) and powdered dried red pepper (Capsicum annuum) was evaluated. METHODS AND RESULTS: Black and red pepper inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium were subjected to 3.81, 7.93, 12.33, 17.04 and 21.67 mg l-1 VHPV for 1 min, and the change in pepper colour was evaluated after treatment. Pathogen quantities decreased with increasing hydrogen peroxide concentration. For black pepper, the 21.67 mg l-1 VHPV treatment decreased E. coli O157:H7 and S. Typhimurium quantities by >6.12 and 4.52 log CFU per gram, respectively, without causing colour change. In addition, the 21.67 mg l-1 VHPV treatment caused 4.35 and 2.36 log CFU per gram reductions in these two pathogen quantities in red pepper, respectively. During the VHPV treatment, colour values of peppers did not significantly change. CONCLUSIONS: VHPV effectively reduced the levels of foodborne pathogens in black and red pepper while inducing minimal colour changes. SIGNIFICANCE AND IMPACT OF THE STUDY: Hydrogen peroxide vapour (HPV) is typically used as a sterilization method for medical devices, and many studies have confirmed the effectiveness of HPV or the gaseous phase of hydrogen peroxide on the inactivation of micro-organisms. However, using HPV for food pasteurization has rarely been studied. In the present study, we confirmed that VHPV effectively reduced the levels of pathogens in black and red pepper without colour changes.


Subject(s)
Capsicum , Escherichia coli O157 , Listeria monocytogenes , Piper nigrum , Colony Count, Microbial , Food Microbiology , Hydrogen Peroxide , Salmonella typhimurium
10.
Food Microbiol ; 108: 104098, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36088114

ABSTRACT

This study investigated the bactericidal activity of plasma-activated water (PAW) generated with a remote discharge reactor against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes. PAW-40, -80, and -120, prepared by activating distilled water for 40, 80, and 120 min, respectively, showed inactivation activity against pathogenic bacteria, which increased as the activation time increased due to decrease in pH and increase in oxidation-reduction potential and reactive oxygen/nitrogen species (RONS) of PAW. In addition, Gram-positive bacteria L. monocytogenes showed superior resistance to PAW than Gram-negative bacteria E. coli O157:H7 and S. Typhimurium. Compared with E. coli O157:H7 and S. Typhimurium, L. monocytogens exhibited less cell membrane damage, lipid peroxidation, and intracellular ROS accumulation after PAW treatment, which indicated that L. monocytogenes exhibited greater resistance because the thick cell wall buffered RONS diffusion into the cell. PAW also showed a control effect on the pathogenic bacteria on cherry tomato, and the effect was maintained throughout five repeated applications; thus, proposing high reusability of PAW. The results of this study propose that PAW generated with a remote discharge reactor can be utilized for pathogen control and provides basic data for related research and practical industrial applications.


Subject(s)
Escherichia coli O157 , Listeria monocytogenes , Water Purification , Cell Membrane , Escherichia coli O157/physiology , Lipid Peroxidation , Listeria monocytogenes/physiology , Reactive Oxygen Species
11.
Appl Environ Microbiol ; 87(15): e0063121, 2021 07 13.
Article in English | MEDLINE | ID: mdl-33990307

ABSTRACT

The aim of this study was to evaluate the antibacterial activity of caffeic acid (CA), which is a natural polyphenol, combined with UV-A light against the representative foodborne bacteria Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes. Data regarding the inactivation of these bacteria and its dependence on CA concentration, light wavelength, and light dose were obtained. E. coli O157:H7 and Salmonella Typhimurium were reduced to the detection limit when treated with 3 mM CA and UV-A for 3 J/cm2 and 4 J/cm2, respectively, and 5 J/cm2 treatment induced 3.10 log reduction in L. monocytogenes. To investigate the mechanism for inactivation of Salmonella Typhimurium and L. monocytogenes, measurement of polyphenol uptake, membrane damage assessment, enzymatic activity assay, and transmission electron microscopy (TEM) were conducted. It was revealed that CA was significantly (P < 0.05) absorbed by bacterial cells, and UV-A light allowed a higher uptake of CA for both pathogens. Additionally, CA plus UV-A treatment induced significant (P < 0.05) cell membrane damage. In the enzymatic activity assay, the activities of both pathogens were reduced by CA, and a greater reduction occurred by use of CA plus UV-A. Moreover, transmission electron microscopy (TEM) images indicated that CA plus UV-A treatment notably destroyed the intercellular structure. In addition, antibacterial activity was also observed in commercial apple juice, which showed results similar to those obtained from phosphate-buffered saline (PBS), resulting in a significant (P < 0.05) reduction for all three pathogens without any changes in color parameters (L*, a*, and b*), total phenolic compounds, and DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity. IMPORTANCE Photodynamic inactivation (PDI), which involves photoactivation of a photosensitizer (PS), is an emerging field of study, as it effectively reduces various kinds of microorganisms. Although there are several PSs that have been used for PDI, there is a need to find naturally occurring PSs for safer application in the food industry. Caffeic acid, a natural polyphenol found in most fruits and vegetables, has recently been studied for its potential to act as a novel photosensitizer. However, no studies have been conducted regarding its antibacterial activity depending on treatment conditions and its antibacterial mechanism. In this study, we closely examined the effectiveness of caffeic acid in combination with UV-A light for inactivating representative foodborne bacteria in liquid medium. Therefore, the results of this research are expected to be utilized as basic data for future application of caffeic acid in PDI, especially when controlling pathogens in liquid food processing.


Subject(s)
Anti-Bacterial Agents/pharmacology , Caffeic Acids/pharmacology , Escherichia coli O157 , Food Preservation/methods , Fruit and Vegetable Juices/microbiology , Listeria monocytogenes , Salmonella typhimurium , Ultraviolet Rays , Cell Membrane/drug effects , Cell Membrane/radiation effects , Escherichia coli O157/drug effects , Escherichia coli O157/growth & development , Escherichia coli O157/metabolism , Escherichia coli O157/radiation effects , Food Microbiology , Fruit , Listeria monocytogenes/drug effects , Listeria monocytogenes/growth & development , Listeria monocytogenes/metabolism , Listeria monocytogenes/radiation effects , Malus , Polyphenols/metabolism , Salmonella typhimurium/drug effects , Salmonella typhimurium/growth & development , Salmonella typhimurium/metabolism , Salmonella typhimurium/radiation effects
12.
Neoplasma ; 68(3): 580-589, 2021 May.
Article in English | MEDLINE | ID: mdl-33618521

ABSTRACT

G protein-coupled receptor 56 (GPR56) belongs to the adhesion G protein-coupled receptor subfamily, which plays a role in cell progression and survival. The aim of this study was to investigate the role of the GPR56 gene in a cell line study and the impact of its protein expression on the prognosis of colorectal cancer (CRC) patients. The effect of GPR56 on tumor cell proliferation (WST-1 assay), invasion (Transwell assay), migration (Transwell assay, wound healing assay), and colony-forming ability (semisolid agar colony-forming assay) was explored. The expression levels of GPR56 in tissue samples of 109 CRC patients were evaluated by immunohistochemistry. The prognostic value of GRP56 was analyzed using univariate and multivariate analyses. The downregulation of GPR56 in the CRC cell line reduced cell proliferation as compared with that in a control sample (48 h; p=0.042, 72 h; p=0.001). Downregulation of the GPR56 expression reduced cell invasion and migration abilities and inhibited colony-forming abilities (p<0.005). The 5-year overall survival rate was worse in the high-expression group as compared with that in the low-expression group (51.6% vs. 74.4%, p=0.008). High GPR56 expression was a significant prognostic factor for overall survival of CRC patients in the univariate (p=0.001) and multivariate (p<0.001) analyses. The expression level of GPR56 plays an important role in tumor progression in CRC, and it may serve as a prognostic indicator in CRC patients.


Subject(s)
Colorectal Neoplasms , Cell Line, Tumor , Cell Movement , Cell Proliferation , Colorectal Neoplasms/genetics , Down-Regulation , Gene Expression Regulation, Neoplastic , Humans , Prognosis
13.
Food Microbiol ; 95: 103676, 2021 May.
Article in English | MEDLINE | ID: mdl-33397610

ABSTRACT

This study investigated the antimicrobial effect of hot water with citric acid against Escherichia coli O157:H7 biofilm on stainless steel (SS). Hot water (50, 60, or 70 °C) with 2% citric acid exhibited a synergistic bactericidal effect on the pathogen biofilm. It was revealed that hot water and citric acid combination induced sub-lethally injured cells. Additionally, mechanisms of the synergistic bactericidal effects of hot water with citric acid were identified through several approaches. In terms of biofilm matrix, hot water removes exopolysaccharides, a major component of extracellular polymeric substances (EPS), thereby increasing contact between surface cells and citric acid, resulting in a synergistic bactericidal effect. In terms of the cell itself, increased permeability of citric acid through cell membranes destructed by hot water promotes the inactivation of superoxide dismutase (SOD) in E. coli O157:H7, which induce synergistic generation of reactive oxygen species (ROS) which promote inactivation of cell by activating lipid peroxidation, resulting in destruction of the cell membrane. Therefore, it is interpreted that when hot water with citric acid is applied to E. coli O157:H7 biofilm, synergy effects on the biofilm matrix and cell itself have a complex interaction with each other, thus causing a dramatic synergistic bactericidal effect.


Subject(s)
Biofilms/drug effects , Citric Acid/pharmacology , Disinfectants/pharmacology , Disinfection/methods , Escherichia coli O157/drug effects , Water/pharmacology , Disinfectants/chemistry , Disinfection/instrumentation , Escherichia coli O157/growth & development , Hot Temperature , Reactive Oxygen Species/metabolism , Stainless Steel/analysis , Water/chemistry
14.
Appl Environ Microbiol ; 86(14)2020 07 02.
Article in English | MEDLINE | ID: mdl-32385086

ABSTRACT

The aim of this research was to investigate the efficacy of the duty ratio and applied voltage in the inactivation of pathogens in soybean curd by pulsed ohmic heating (POH). The heating rate of soybean curd increased rapidly as the applied voltage increased, although the duty ratio did not affect the temperature profile. We supported this result by verifying that electrical conductivity increased with the applied voltage. Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in soybean curd were significantly (P < 0.05) inactivated by more than 1 log unit at 80 Vrms (root mean square voltage). To elucidate the mechanism underlying these results, the membrane potential of the pathogens was examined using DiBAC4(3) [bis-(1,3-dibutylbarbituric acid)trimethine oxonol] on the basis of a previous study showing that the electric field generated by ohmic heating affected the membrane potential of cells. The values of DiBAC4(3) accumulation increased under increasing applied voltage, and they were significantly (P < 0.05) higher at 80 Vrms, while the duty ratio had no effect. In addition, morphological analysis via transmission electron microscopy showed that electroporation and expulsion of intracellular materials were predominant at 80 Vrms Moreover, electrode corrosion was overcome by the POH technique, and the textural and color properties of soybean curd were preserved. These results substantiate the idea that the applied voltage has a profound effect on the microbial inactivation of POH as a consequence of not only the thermal effect, but also the nonthermal effect, of the electric field, whereas the duty ratio does not have such an effect.IMPORTANCE High-water-activity food products, such as soybean curd, are vulnerable to microbial contamination, which causes fatal foodborne diseases and food spoilage. Inactivating microorganisms inside food is difficult because the transfer of thermal energy is slower inside than it is outside the food. POH is an adequate sterilization technique because of its rapid and uniform heating without causing electrode corrosion. To elucidate the electrical factors associated with POH performance in the inactivation of pathogens, the effects of the applied voltage and duty ratio on POH were investigated. In this study, we verified that a high applied voltage (80 Vrms) at a duty ratio of 0.1 caused thermal and nonthermal effects on pathogens that led to an approximately 4-log-unit reduction in a significantly short time. Therefore, the results of this research corroborate database predictions of the inactivation efficiency of POH based on pathogen control strategy modeling.


Subject(s)
Escherichia coli O157/physiology , Glycine max/physiology , Hot Temperature , Listeria monocytogenes/physiology , Membrane Potentials , Microbial Viability , Salmonella typhimurium/physiology , Fermentation , Heating/methods , Kinetics
15.
Appl Environ Microbiol ; 86(11)2020 05 19.
Article in English | MEDLINE | ID: mdl-32220842

ABSTRACT

The aim of this study was to investigate the sporicidal effect of a krypton-chlorine (KrCl) excilamp against Alicyclobacillus acidoterrestris spores and to compare its inactivation mechanism to that of a conventional UV lamp containing mercury (Hg). The inactivation effect of the KrCl excilamp was not significantly different from that of the Hg UV lamp for A. acidoterrestris spores in apple juice despite the 222-nm wavelength of the KrCl excilamp having a higher absorption coefficient in apple juice than the 254-nm wavelength of the Hg UV lamp; this is because KrCl excilamps have a fundamentally greater inactivation effect than Hg UV lamps, which is confirmed under ideal conditions (phosphate-buffered saline). The inactivation mechanism analysis revealed that the DNA damage induced by the KrCl excilamp was not significantly different (P > 0.05) from that induced by the Hg UV lamp, while the KrCl excilamp caused significantly higher (P < 0.05) lipid peroxidation incidence and permeability change in the inner membrane of A. acidoterrestris spores than did the Hg UV lamp. Meanwhile, the KrCl excilamp did not generate significant (P > 0.05) intracellular reactive oxygen species, indicating that the KrCl excilamp causes damage only through the direct absorption of UV light. In addition, after KrCl excilamp treatment with a dose of 2,011 mJ/cm2 to reduce A. acidoterrestris spores in apple juice by 5 logs, there were no significant (P > 0.05) changes in quality parameters such as color (L*, a*, and b*), total phenolic compounds, and DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity.IMPORTANCEAlicyclobacillus acidoterrestris spores, which have high resistance to thermal treatment and can germinate even at low pH, are very troublesome in the juice industry. UV technology, a nonthermal treatment, can be an excellent means to control heat-resistant A. acidoterrestris spores in place of thermal treatment. However, the traditionally applied UV sources are lamps that contain mercury (Hg), which is harmful to humans and the environment; thus, there is a need to apply novel UV technology without the use of Hg. In response to this issue, excilamps, an Hg-free UV source, have been actively studied. However, no studies have been conducted applying this technique to control A. acidoterrestris spores. Therefore, the results of this study, which applied a KrCl excilamp for the control of A. acidoterrestris spores and elucidated the inactivation principle, are expected to be utilized as important basic data for application to actual industry or conducting further studies.


Subject(s)
Alicyclobacillus/radiation effects , Anti-Bacterial Agents/analysis , Fruit and Vegetable Juices/analysis , Lasers, Excimer , Malus/chemistry , Spores, Bacterial/radiation effects , Fruit and Vegetable Juices/radiation effects , Malus/radiation effects
16.
Retina ; 40(7): 1245-1254, 2020 Jul.
Article in English | MEDLINE | ID: mdl-31095063

ABSTRACT

PURPOSE: To investigate disease activity in patients with Type 3 neovascularization undergoing anti-vascular endothelial growth factor treatment through image analysis using optical coherence tomography angiography (OCTA). METHODS: Thirty-nine treatment-naive eyes with Type 3 neovascularization were included in the retrospective analysis. All patients were treated with three loading injections of an anti-vascular endothelial growth factor agent, followed by further injections as needed. Changes in the Type 3 lesion were analyzed through OCTA imaging during the 12 months of follow-up. RESULTS: The high-flow signal of Type 3 neovascularization on OCTA images disappeared in 46.2% eyes (19 of 39) and was persistent in 53.8% eyes (20 of 39) after loading injections. A persistent high-flow signal on OCTA after treatment was found at the sub-retinal pigment epithelium in 65.0% eyes (13 of 20), deep vascular plexus in 30.0% eyes (6 of 20), and outer neurosensory retina in 15.0% eyes (3 of 20). Eyes without lesions on OCTA images received significantly fewer injections (3.7 vs. 5.5; P = 0.016) and showed a longer retreatment-free period (mean 7.57 vs. 4.07 months; P = 0.002) during the 12-month follow-up than eyes with a persistent high-flow signal on OCTA. However, no significant between-group difference was observed in terms of improved visual acuity. CONCLUSION: Patients with Type 3 neovascularization who had no lesion on an OCTA scan after anti-vascular endothelial growth factor treatment showed a lower recurrence rate and maintained visual acuity with fewer injections than those with persistent high-flow lesions on an OCTA scan. Optical coherence tomography angiography may provide an additional biomarker for clinical guidance in the treatment and monitoring of disease activity in Type 3 neovascularization.


Subject(s)
Choroid/pathology , Fluorescein Angiography/methods , Ranibizumab/administration & dosage , Tomography, Optical Coherence/methods , Visual Acuity , Wet Macular Degeneration/drug therapy , Aged , Angiogenesis Inhibitors/administration & dosage , Female , Follow-Up Studies , Fundus Oculi , Humans , Intravitreal Injections , Male , Retrospective Studies , Treatment Outcome , Vascular Endothelial Growth Factor A/antagonists & inhibitors , Wet Macular Degeneration/diagnosis
17.
Sensors (Basel) ; 20(22)2020 Nov 19.
Article in English | MEDLINE | ID: mdl-33227915

ABSTRACT

This study aims at creating low-cost, three-dimensional (3D), freehand ultrasound image reconstructions from commercial two-dimensional (2D) probes. The low-cost system that can be attached to a commercial 2D ultrasound probe consists of commercial ultrasonic distance sensors, a gimbal, and an inertial measurement unit (IMU). To calibrate irregular movements of the probe during scanning, relative position data were collected from the ultrasonic sensors that were attached to a gimbal. The directional information was provided from the IMU. All the data and 2D ultrasound images were combined using a personal computer to reconstruct 3D ultrasound image. The relative position error of the proposed system was less than 0.5%. The overall shape of the cystic mass in the breast phantom was similar to those from 2D and sections of 3D ultrasound images. Additionally, the pressure and deformations of lesions could be obtained and compensated by contacting the probe to the surface of the soft tissue using the acquired position data. The proposed method did not require any initial marks or receivers for the reconstruction of a 3D ultrasound image using a 2D ultrasound probe. Even though our system is less than $500, a valuable volumetric ultrasound image could be provided to the users.

18.
Int J Mol Sci ; 21(21)2020 Oct 26.
Article in English | MEDLINE | ID: mdl-33114545

ABSTRACT

HJURP is a key factor for CENP-A deposition and maintenance in centromeres. The role of mis-regulation of histone chaperones in cancer initiation and progression has been studied. However, its role in colorectal cancer is still unclear. In this study, we aimed to evaluate the expression of HJURP in 162 colorectal cancer tissue. To investigate the function of HJURP in the colorectal cancer cell, we suppressed HJURP expression by siRNA and confirmed proliferation, migration, invasion, and anchorage independent of colony forming ability. The association between HJURP expression levels and clinicopathological factors was evaluated in 162 CRC tissues using immunohistochemistry. The overall survival rate in patients of HJURP high expression was higher than those in HJURP low expression in CRC. Suppressing HJURP expression decreased cellular proliferation, invasion, and migration in four CRC cell lines: HT29, HCT116, SW480, SW620 in vitro study. Our findings revealed that the knockdown of HJURP suppressed the proliferation, migration, invasion, and tumorigenicity in CRC cells. Due to its strong association with CRC, HJURP could be a potential prognostic biomarker and a novel target for drug discovery.


Subject(s)
Biomarkers, Tumor/metabolism , Colorectal Neoplasms/surgery , DNA-Binding Proteins/metabolism , Up-Regulation , Cell Line, Tumor , Cell Movement , Cell Proliferation , Colorectal Neoplasms/metabolism , Female , Gene Expression Regulation, Neoplastic , HCT116 Cells , HT29 Cells , Humans , Male , Prognosis , Survival Analysis , Treatment Outcome
19.
Appl Environ Microbiol ; 85(12)2019 06 15.
Article in English | MEDLINE | ID: mdl-30952663

ABSTRACT

In this study, we developed a washing system capable of decontaminating fresh produce by combining the Spindle apparatus, which detaches microorganisms on sample surfaces, and a 222-nm krypton-chlorine excimer lamp (KrCl excilamp) (Sp-Ex) and investigated their decontamination effect against Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes on apple (Malus domestica Borkh.) and bell pepper (Capsicum annuum L.) surfaces. Initial levels of the three pathogens were approximately 108 CFU/sample. Both E. coli O157:H7 and S. Typhimurium were reduced to below the detection limit (2.0 log CFU/sample) after 5 and 7 min of treatment on apple and bell pepper surfaces, respectively. The amounts of L. monocytogenes on apple and bell pepper surfaces were reduced by 4.26 and 5.48 logs, respectively, after 7 min of treatment. The decontamination effect of the Sp-Ex was influenced by the hydrophobicity of the sample surface as well as the microbial cell surface, and the decontamination effect decreased as the two hydrophobicity values increased. To improve the decontamination effect of the Sp-Ex, Tween 20, a surfactant that weakens the hydrophobic interaction between the sample surface and pathogenic bacteria, was incorporated into Sp-Ex processing. It was found that its decontamination effect was significantly (P < 0.05) increased by the addition of 0.1% Tween 20. Sp-Ex did not cause significant quality changes in apple or bell pepper surfaces during 7 days storage following treatment (P > 0.05). Our results suggest that Sp-Ex could be applied as a system to control pathogens in place of chemical sanitizer washing by the fresh-produce industry.IMPORTANCE Although most fresh-produce processing currently controls pathogens by means of washing with sanitizers, there are still problems such as the generation of harmful substances and changes in product quality. A combination system composed of the Spindle and a 222-nm KrCl excilamp (Sp-Ex) developed in this study reduced pathogens on apple and bell pepper surfaces using sanitizer-free water without altering produce color and texture. This study demonstrates the potential of the Sp-Ex to replace conventional washing with sanitizers, and it can be used as baseline data for practical application by industry. In addition, implementation of the Sp-Ex developed in this study is expected not only to meet consumer preference for fresh, minimally processed produce but also to reduce human exposure to harmful chemicals while being beneficial to the environment.


Subject(s)
Capsicum/microbiology , Chlorine/pharmacology , Decontamination/methods , Disinfectants/pharmacology , Krypton/pharmacology , Lasers, Excimer , Malus/microbiology , Decontamination/instrumentation , Escherichia coli O157/radiation effects , Food Microbiology , Listeria monocytogenes/radiation effects , Salmonella typhimurium/radiation effects
20.
Appl Environ Microbiol ; 85(1)2019 01 01.
Article in English | MEDLINE | ID: mdl-30315076

ABSTRACT

The purpose of this study was to investigate the synergistic bactericidal effect of 222-nm KrCl excilamp and 254-nm low-pressure (LP) Hg lamp simultaneous treatment against Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Typhimurium, and Listeria monocytogenes in tap water and to identify the synergistic bactericidal mechanism. Sterilized tap water inoculated with pathogens was treated individually or simultaneously with a 254-nm LP Hg lamp or 222-nm KrCl excilamp. Overall, for all pathogens, an additional reduction was found compared to the sum of the log unit reductions of the individual treatments resulting from synergy in the simultaneous treatment with both kinds of lamps. In order to identify the mechanism of this synergistic bactericidal action, the form and cause of membrane damage were analyzed. Total reactive oxygen species (ROS) and superoxide generation as well as the activity of ROS defense enzymes then were measured, and the overall mechanism was described as follows. When the 222-nm KrCl excilamp and the 254-nm LP Hg lamp were treated simultaneously, inactivation of ROS defense enzymes by the 222-nm KrCl excilamp induced additional ROS generation following exposure to 254-nm LP Hg lamp (synergistic) generation, resulting in synergistic lipid peroxidation in the cell membrane. As a result, there was a synergistic increase in cell membrane permeability leading to a synergistic bactericidal effect. This identification of the fundamental mechanism of the combined disinfection system of the 222-nm KrCl excilamp and 254-nm LP Hg lamp, which exhibited a synergistic bactericidal effect, can provide important baseline data for further related studies or industrial applications in the future.IMPORTANCE Contamination of pathogenic microorganisms in water plays an important role in inducing outbreaks of food-borne illness by causing cross-contamination in foods. Thus, proper disinfection of water before use in food production is essential to prevent outbreaks of food-borne illness. As technologies capable of selecting UV radiation wavelengths (such as UV-LEDs and excilamps) have been developed, wavelength combination treatment with UV radiation, which is widely used in water disinfection systems, is actively being studied. In this regard, we have confirmed synergistic bactericidal effects in combination with 222-nm and 254-nm wavelengths and have identified mechanisms for this. This study clearly analyzed the mechanism of synergistic bactericidal effect by wavelength combination treatment, which has not been attempted in other studies. Therefore, it is also expected that these results will play an important role as baseline data for future research on, as well as industrial applications for, the disinfection strategy of effective wavelength combinations.


Subject(s)
Disinfection/methods , Drinking Water/microbiology , Escherichia coli O157/radiation effects , Microbial Viability/radiation effects , Salmonella typhimurium/radiation effects , Ultraviolet Rays , Chlorine/chemistry , Krypton/chemistry , Mercury/chemistry
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