Nagendran Rajalingam | Chonbuk National University (original) (raw)

Papers by Nagendran Rajalingam

International journal of food microbiology, Jun 1, 2024

Identification and characterization of putative light sensing genes in Pseudomonas cichorii JBC1.

Pseudomonas cichorii is an economically important pathogen which infects many vegetables and orna... more Pseudomonas cichorii is an economically important pathogen which infects many vegetables and ornamentals worldwide. In spite of many studies to understand the underlying mechanisms in virulence of Pseudomonas spp, the function of srf cluster including srfC, which is formerly known as HopL1, a type 3 effecter protein remains an enigma in plant pathology. In this study, we knocked out srfA, srfB, srfC, and srfD genes from the srf cluster of P. cichorii JBC1 (JBC1) individually to study their role in the virulence and life style of the patho-gen. When we performed seedling-flood inoculation assay using tomato seed-lings, we observed significant reduction in disease symptoms in the seedlings infected with △srfC strain compared with those infected with complemented strain (△srfC::psrfC), △srfA, △srfB and, △srfD strains which exhibited severe symp-toms as that of the JBC1 strain. Subsequently, we infected mature tomato plants by dipping inoculation with bacterial suspensions of △srfC, △sr...

Phytopathology, Apr 1, 2015

Green and red light reduces the disease severity by Pseudomonas cichorii JBC1 in tomato plants vi... more Green and red light reduces the disease severity by Pseudomonas cichorii JBC1 in tomato plants via upregulation of defense-related gene expression. Phytopathology 105:412-418. Light influences many physiological processes in most organisms. To investigate the influence of light on plant and pathogen interaction, we challenged tomato seedlings with Pseudomonas cichorii JBC1 by flood inoculation and incubated the seedlings under different light conditions. Tomato seedlings exposed to green or red light showed a significant reduction in disease incidence compared with those grown under white light or dark conditions. To understand the underlying mechanisms, we investigated the effects of each light wavelength on P. cichorii JBC1 and tomato plants. Treatment with various light wavelengths at 120 µmol m-2 s-1 revealed no significant difference in growth, swarming motility, or biofilm formation of the pathogen. In addition, when we vacuum-infiltrated P. cichorii JBC1 into tomato plants, green and red light also suppressed disease incidence which indicated that the reduced disease severity was not from direct influence of light on the pathogen. Significant upregulation of the defense-related genes, phenylalanine ammonia-lyase (PAL) and pathogenesis-related protein 1a (PR-1a) was observed in P. cichorii JBC1-infected tomato seedlings grown under green or red light compared with seedlings grown under white light or dark conditions. The results of this study indicate that light conditions can influence plant defense mechanisms. In particular, green and red light increase the resistance of tomato plants to infection by P. cichorii.

The Korean Society Of Environmental Agriculture, Dec 1, 2020

Frontiers in Microbiology

Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as h... more Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as healthy additions to multiple dishes. Microbial contamination of lettuce is a major concern, as lettuce is consumed fresh without cooking. Among foodborne pathogens, the spore-forming, facultative anaerobic bacterium, Bacillus cereus is one of the frequently detected pathogen in lettuce in Korea. In this study, we investigated the prevalence and distribution of Bacillus cereus strains in lettuce production farms and further evaluated the enterotoxin gene profiles, antibiotic susceptibility, multidrug resistance pattern, and genetic differences among the B. cereus group isolates. Of the 140 samples isolated from 10 lettuce production farms, 30 samples (21.42%) were positive for B. cereus in which 19 (31.6%) and 10 (23.25%) were from soil and lettuce, respectively. The enterotoxin patterns A (hblCDA, nheABC, entFM, and cytK genes) and B (hblCDA, nheABC, and entFM genes) accounted for 50% an...

Applied Biological Chemistry, 2021

This study was conducted to investigate the prevalence of coliforms and Escherichia coli across r... more This study was conducted to investigate the prevalence of coliforms and Escherichia coli across radish sprout production facilities in the Republic of Korea and to characterize isolated E. coli. A total of 324 samples were collected from three different radish sprout production units in spring and summer. Overall, the levels of coliforms were significantly higher (> 3.75 log CFU/g) in radish sprouts during summer season than in spring. E. coli was detected in the pre-harvest (50%) and post-harvest (39%) sprouts and water samples (33%) from farms B and C. Of the 48 E. coli isolates, five E. coli isolates were positive for the eaeA gene, indicative of EPEC O110, two isolates were eaeA-positive (EPEC ONT) and one isolate was ipaH-positive (ETEC O71). These three E. coli strains were identified as novel sequence types by the multilocus sequence-typing assay based on the combination of allelic profiles. In addition, the EPEC O110 isolates obtained from the stream water stored in conta...

Korean Journal of Environmental Agriculture, 2020

BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination i... more BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination in agricultural products. In addition, anti-microbial resistance (AMR) bacteria in food products possess serious threat to humans. This study was aimed at investigating the prevalence of foodborne bacteria in irrigation water and evaluating their anti-microbial susceptibility. METHODS AND RESULTS: Surface water (n = 66 sites) and groundwater (n = 40 sites) samples were collected from the Gyeongi and Gangwon provinces of South Korea during April, July, and October 2019. To evaluate the safety of water, fecal indicators (Escherichia coli) and foodborne pathogens (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were examined. E. coli isolates from water were further tested for antimicrobial susceptibility using VITEK2 system. Overall, detection rate of foodborne pathogens in July was highest among three months. The prevalence of pathogenic E. coli (24%), Salmonella (3%), and L. monocytogenes (3%) was higher in surface water, while only one ground water site was contained with pathogenic E. coli (2.5%). Of the 343 E. coli isolates, 22.7% isolates were resistant to one or more antimicrobials (ampicillin (18.7%), trimethoprim-sulfamethoxazole (7.0%), and ciprofloxacin (6.7%)). CONCLUSION: To enhance the safety of agricultural products, it is necessary to frequently monitor the microbial quality of water.

Plant Pathology, 2019

Èlánek se zabývá otázkou transformace frazeologických jednotek, jejich aktualizací, vznikem neolo... more Èlánek se zabývá otázkou transformace frazeologických jednotek, jejich aktualizací, vznikem neologismù v umìleckém stylu. Souèasný jazyk, jak èeský, tak i ukrajinský, aktivnì reaguje na spoleèenské zmìny a aktuální problémy v rùzných oblastech spoleèenského života, což se projevuje v urèité míøe i ve frazeologii, kde vznikají nové jednotky-frazeologické neologismy. Pøíklady nìkterých strukturnì sémantických zmìn frazeologismù a vznik autorských okazionalizmù jsou proanalyzovány na pøíkladu knihy Evy Hauserové Noc v Mejdlovarnì. Pøeklad do ukrajinštiny a porovnání ekvivalentnosti potvrzuje teorii, že frazeologizmy a stejnì tak i frazeologické neologismy nejsou vždy jednoznaènì èi snadno transponovatelné do jazyka jiného. Dané bádání otevírá perspektivy pro další studium a analýzu èeských frazeologických neologismù a jejich pøeklad do ukrajinštiny. Z didaktického hlediska umístìní do výuky frazeologizmù a neofrazeologizmù rozhodnì oživuje studium cizího, v našem pøípadì èeského, jazyka, obohacuje lexikální zásobu i lingvokulturní znalosti studentù, rozšiøuje jejich komunikativní možnosti, èímž jim umožòuje poznat ve vší hloubce krásu èeského jazyka. Klíèová slova: modifikace frazeologických jednotek, transformace frazeologizmù, individuální autorské aktualizace frazémù, okazionalismy, frazeologické neologismy. ФРАЗЕОЛОГІЧНІ НЕОЛОГІЗМИ Й ОКАЗІОНАЛІЗМИ В СУЧАСНІЙ ЧЕСЬКІЙ ЛІТЕРАТУРІ (на прикладі твору Є. Гаусерової "Ніч у Миловарні") ГАРБУЗОВА Радка аспірант Київський національний лінгвістичний університет

Mycobiology, 2019

Fungi produce various secondary metabolites that have beneficial and harmful effects on other org... more Fungi produce various secondary metabolites that have beneficial and harmful effects on other organisms. Those bioactive metabolites have been explored as potential medicinal and antimicrobial resources. However, the activities of the culture filtrate (CF) and metabolites of whiterot fungus (Schizophyllum commune) have been underexplored. In this study, we assayed the antimicrobial activities of CF obtained from white-rot fungus against various plant pathogens and evaluated its efficacy for controlling anthracnose and gray mold in pepper plants. The CF inhibited the mycelial growth of various fungal plant pathogens, but not of bacterial pathogens. Diluted concentrations of CF significantly suppressed the severity of anthracnose and gray mold in pepper fruits. Furthermore, the incidence of anthracnose in field conditions was reduced by treatment with a 12.5% dilution of CF. The active compound responsible for the antifungal and disease control activity was identified and verified as schizostatin. Our results indicate that the CF of white-rot fungus can be used as an eco-friendly natural product against fungal plant pathogens. Moreover, the compound, schizostatin could be used as a biochemical resource or precursor for development as a pesticide. To the best of our knowledge, this is the first report on the control of plant diseases using CF and active compound from white-rot fungus. We discussed the controversial antagonistic activity of schizostatin and believe that the CF of white-rot fungus or its active compound, schizostatin, could be used as a biochemical pesticide against fungal diseases such as anthracnose and gray mold in many vegetables.

The plant pathology journal, 2016

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic ... more Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (≥ 10(6) cfu/ml) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (ΦPSII) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII (Fv/Fm) was altered well after symptom development. Visible/near infrared and chlorophyll fluores...

European Journal of Plant Pathology, 2017

Increasing evidence suggests that the interactions between plant and pathogen are influenced by l... more Increasing evidence suggests that the interactions between plant and pathogen are influenced by light perception of both organisms. In our previous study, green light decreased disease severity in tomato plants in response to Pseudomonas cichoriiJBC1 (PcJBC1) infection via induction of disease resistance-related genes. However, the influence of green light on gene expression and metabolism of PcJBC1 has not been explored. In this study, we cultured PcJBC1 in hrp-inducing minimal media (MM) under green light and dark condition, and analyzed the expression of genes, which are important in pathogenicity/virulence and epiphytic survival by real-time PCR (qPCR). Although no significant changes were observed in the expression of type 3 secretion system (T3SS)- and flagellar-related genes in response to green light, genes for the production of phytotoxic lipopeptides and siderophores were significantly reduced by green light. In addition, the phytotoxic lipopeptide and siderophore production in the culture supernatant was consistent with the results of gene expression. Furthermore, we compared the whole transcriptomes of PcJBC1 grown in MM under green light and dark condition. Among 243 differentially expressed genes (>2-fold change), the photoreceptor genes, bacteriophytochrome (bphP) and heme-oxygenase (bphO) were significantly up-regulated, whereas genes involved in the type 1 secretion system (T1SS), type 6 secretion system (T6SS), phytotoxic lipopeptides, and iron acquisition were profoundly repressed under green light. Corresponding to qPCR analysis, the RNA-seq results also showed no significant alteration in the T3SS- and flagellar-related genes. Overall, our results suggest that green light perceived by PcJBC1 plays a key role in diverse physiological responses that might affect this pathogen’s epiphytic survival. The receptor and signaling network involved in green light perception should be identified in further investigation.

Korean Journal of Environmental Agriculture

BACKGROUND: Contaminated water was a major source of food-borne pathogens in various recent fresh... more BACKGROUND: Contaminated water was a major source of food-borne pathogens in various recent fresh producerelated outbreaks. This study was conducted to investigate the microbial contamination level and correlations between the level of sanitary indicator bacteria and the detection ratio of pathogens in agricultural water by logistic regression analysis. METHODS AND RESULTS: Agricultural water was collected from 457 sites including surface water (n=300 sites) and groundwater (n=157 sites) in South Korea from 2018 to 2020. Sanitary indicator bacteria (total coliform, fecal coliform, and Escherichia coli) and food-borne pathogens (pathogenic E. coli, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were analyzed. In surface water, the coliform, fecal coliform, and E. coli were 3.27±0.89 log CFU/100 mL, 1.90±1.19 log CFU/100 mL, and 1.39±1.26 log CFU/100 mL, respectively. For groundwater, three kinds of sanitary indicators ranged in the level from 0.09-0.57 log CFU/100 mL. Pathogenic E. coli, Salmonella and Listeria monocytogenes were detected from 3%-site, 1.5%site, and 0.6%-site water samples, respectively. According to the results of correlations between the level of sanitary indicator bacteria and the detection ratio of pathogens by logistic regression analysis, the probability of pathogen detection increased individually by 1.45 and 1.34 times as each total coliform and E. coli concentration increased by 1 log CFU/100mL. The accuracy of the model was 70.4%, and sensitivity and specificity were 81.5% and 51.7%, respectively. CONCLUSION(S): The results indicate the need to manage the microbial risk of agricultural water to enhance the safety of fresh produce. In addition, logistic regression analysis is useful to analyze the correlation between the level of sanitary indicator bacteria and the detection ratio of pathogens in agricultural water.

This study aimed to establish appropriate conditions for the washing and storage of radish microg... more This study aimed to establish appropriate conditions for the washing and storage of radish microgreens by evaluating the effect of a sodium hypochlorite (NaOCl) wash on the growth of Escherichia coli and Listeria monocytogenes. Sodium hypochlorite (50, 100, 150 and 200 mg/L) was added to wash water and radish microgreens were treated for 5, 10, 15, 20, 25 and 30 min. Treatment with NaOCl (150 mg/L, 5 min) significantly reduced (2.3 log CFU/g) the populations of both bacteria (p<0.05). After washing, the levels of bacteria in NaOCl treated radish microgreens was evaluated during storage at 4°C, 10°C, 15°C and 20°C for 3 days. The growths of E. coli and L. monocytogenes increased rapidly at temperatures over 15°C and 10°C respectively, from day 1. We believed that NaOCl treatmentinduced injuries may have caused the release of exudate on microgreen surfaces, which could have facilitated the growth of the pathogens at temperatures >10°C. To validate this hypothesis, we inoculated ...

The Plant Pathology Journal

Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However,... more Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from...

Journal of Food Hygiene and Safety

Listeria monocytogenes (L. monocytogenes) was responsible for several recall cases owing to its i... more Listeria monocytogenes (L. monocytogenes) was responsible for several recall cases owing to its incidence in mushrooms exported from the Republic of Korea. In this study, we investigated the survival of L. monocytogenes in enoki mushroom (Flammulina velutipes) at different temperatures and the antilisterial effect of its organic acids. Enoki mushrooms were innoculated with L. monocytogenes (initial concentration 4.5 log CFU/g) and stored at 1-35 o C, No growth of L. monocytogenes in enoki mushrooms was observed at 1 o C for 30 days. 3.0 log CFU/ g growth of L. monocytogenes was also achieved after 36 h and 24 h at 30 o C and 35 o C, respectively. To evaluate the antilisterial effect of the organic acids (acetic acid, lactic acid, malic acid), enoki mushrooms were treated with 1-3% of each acid for 10-30 min. The efficacy of malic acid and lactic acid was significantly higher than that of acetic acid. Over 3.0 log reductions were observed when L. monocytogenes in enoki mushrooms was immersed in 3% lactic acid and malic acid over 10 minutes or more. Therefore, it is necessary to keep enoki mushrooms at 1 o C during the export process and treat them with 3% lactic acid and malic acid for 10 min prior to consumption.

Foods

Contamination by Listeria monocytogenes in packaged produce is a major concern. The purpose of th... more Contamination by Listeria monocytogenes in packaged produce is a major concern. The purpose of this study was to find natural and affordable sanitizers to reduce L. monocytogenes contamination in agricultural products. Organic acids, ultraviolet-C (UV-C), and ethanol were analyzed either alone or in combination to assess their ability to reduce L. monocytogenes population in radish, oriental melon, and carrot samples. In radish samples, 3% malic acid combined with UV-C at a dosage of 144 mj/cm2 significantly reduced (>4 log CFU/g) the population of L. monocytogenes (1.44 ± 0.5) compared to the control sample (5.14 ± 0.09). In the case of the melon samples, exposure to UV-C at a dosage of 144 mj/cm2 combined with 3% lactic acid (2.73 ± 0.75) or 50% ethanol (2.30 ± 0.01) was effective against L. monocytogenes compared to the control sample (5.10 ± 0.19). In carrot samples, 3% lactic acid combined with 144 mj/cm2 dosage UV-C reduced L. monocytogenes population (4.48 ± 0.25) more tha...

Journal of Food Hygiene and Safety

This study was undertaken to compare the efficacy of different sample preparation (stomaching, pu... more This study was undertaken to compare the efficacy of different sample preparation (stomaching, pulsifying, and sonication) and DNA extraction methods (boiling and commercial kit) for detection of enterotoxinproducing Clostridium perfringens from produce by polymerase chain reaction (PCR). Each produce type was inoculated at concentrations of 10 2 , 10 3 , 10 4 , 10 5 , 10 6 , and 10 7 spores/g. Produce inoculated with spores was treated with three sample preparation methods, and DNA was extracted by boiling method and a commercial kit, followed by PCR. The detection limit of stomached samples was lower than that of pummeled and sonicated samples by 10-100 times. Moreover, the DNA extraction efficiency of the commercial kit was found to be superior to that of boiling. In particular, the PCR efficiency of cherry tomato and perilla leaf samples was greatly affected by sample preparation and DNA extraction method. These data suggest that DNA extraction with a commercial kit after pulsification is an optimum sample preparation method for detection of C. perfringens by PCR.

International journal of food microbiology, Jun 1, 2024

Identification and characterization of putative light sensing genes in Pseudomonas cichorii JBC1.

Pseudomonas cichorii is an economically important pathogen which infects many vegetables and orna... more Pseudomonas cichorii is an economically important pathogen which infects many vegetables and ornamentals worldwide. In spite of many studies to understand the underlying mechanisms in virulence of Pseudomonas spp, the function of srf cluster including srfC, which is formerly known as HopL1, a type 3 effecter protein remains an enigma in plant pathology. In this study, we knocked out srfA, srfB, srfC, and srfD genes from the srf cluster of P. cichorii JBC1 (JBC1) individually to study their role in the virulence and life style of the patho-gen. When we performed seedling-flood inoculation assay using tomato seed-lings, we observed significant reduction in disease symptoms in the seedlings infected with △srfC strain compared with those infected with complemented strain (△srfC::psrfC), △srfA, △srfB and, △srfD strains which exhibited severe symp-toms as that of the JBC1 strain. Subsequently, we infected mature tomato plants by dipping inoculation with bacterial suspensions of △srfC, △sr...

Phytopathology, Apr 1, 2015

Green and red light reduces the disease severity by Pseudomonas cichorii JBC1 in tomato plants vi... more Green and red light reduces the disease severity by Pseudomonas cichorii JBC1 in tomato plants via upregulation of defense-related gene expression. Phytopathology 105:412-418. Light influences many physiological processes in most organisms. To investigate the influence of light on plant and pathogen interaction, we challenged tomato seedlings with Pseudomonas cichorii JBC1 by flood inoculation and incubated the seedlings under different light conditions. Tomato seedlings exposed to green or red light showed a significant reduction in disease incidence compared with those grown under white light or dark conditions. To understand the underlying mechanisms, we investigated the effects of each light wavelength on P. cichorii JBC1 and tomato plants. Treatment with various light wavelengths at 120 µmol m-2 s-1 revealed no significant difference in growth, swarming motility, or biofilm formation of the pathogen. In addition, when we vacuum-infiltrated P. cichorii JBC1 into tomato plants, green and red light also suppressed disease incidence which indicated that the reduced disease severity was not from direct influence of light on the pathogen. Significant upregulation of the defense-related genes, phenylalanine ammonia-lyase (PAL) and pathogenesis-related protein 1a (PR-1a) was observed in P. cichorii JBC1-infected tomato seedlings grown under green or red light compared with seedlings grown under white light or dark conditions. The results of this study indicate that light conditions can influence plant defense mechanisms. In particular, green and red light increase the resistance of tomato plants to infection by P. cichorii.

The Korean Society Of Environmental Agriculture, Dec 1, 2020

Frontiers in Microbiology

Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as h... more Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as healthy additions to multiple dishes. Microbial contamination of lettuce is a major concern, as lettuce is consumed fresh without cooking. Among foodborne pathogens, the spore-forming, facultative anaerobic bacterium, Bacillus cereus is one of the frequently detected pathogen in lettuce in Korea. In this study, we investigated the prevalence and distribution of Bacillus cereus strains in lettuce production farms and further evaluated the enterotoxin gene profiles, antibiotic susceptibility, multidrug resistance pattern, and genetic differences among the B. cereus group isolates. Of the 140 samples isolated from 10 lettuce production farms, 30 samples (21.42%) were positive for B. cereus in which 19 (31.6%) and 10 (23.25%) were from soil and lettuce, respectively. The enterotoxin patterns A (hblCDA, nheABC, entFM, and cytK genes) and B (hblCDA, nheABC, and entFM genes) accounted for 50% an...

Applied Biological Chemistry, 2021

This study was conducted to investigate the prevalence of coliforms and Escherichia coli across r... more This study was conducted to investigate the prevalence of coliforms and Escherichia coli across radish sprout production facilities in the Republic of Korea and to characterize isolated E. coli. A total of 324 samples were collected from three different radish sprout production units in spring and summer. Overall, the levels of coliforms were significantly higher (> 3.75 log CFU/g) in radish sprouts during summer season than in spring. E. coli was detected in the pre-harvest (50%) and post-harvest (39%) sprouts and water samples (33%) from farms B and C. Of the 48 E. coli isolates, five E. coli isolates were positive for the eaeA gene, indicative of EPEC O110, two isolates were eaeA-positive (EPEC ONT) and one isolate was ipaH-positive (ETEC O71). These three E. coli strains were identified as novel sequence types by the multilocus sequence-typing assay based on the combination of allelic profiles. In addition, the EPEC O110 isolates obtained from the stream water stored in conta...

Korean Journal of Environmental Agriculture, 2020

BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination i... more BACKGROUND: Irrigation water is known to be one of the major sources of bacterial contamination in agricultural products. In addition, anti-microbial resistance (AMR) bacteria in food products possess serious threat to humans. This study was aimed at investigating the prevalence of foodborne bacteria in irrigation water and evaluating their anti-microbial susceptibility. METHODS AND RESULTS: Surface water (n = 66 sites) and groundwater (n = 40 sites) samples were collected from the Gyeongi and Gangwon provinces of South Korea during April, July, and October 2019. To evaluate the safety of water, fecal indicators (Escherichia coli) and foodborne pathogens (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were examined. E. coli isolates from water were further tested for antimicrobial susceptibility using VITEK2 system. Overall, detection rate of foodborne pathogens in July was highest among three months. The prevalence of pathogenic E. coli (24%), Salmonella (3%), and L. monocytogenes (3%) was higher in surface water, while only one ground water site was contained with pathogenic E. coli (2.5%). Of the 343 E. coli isolates, 22.7% isolates were resistant to one or more antimicrobials (ampicillin (18.7%), trimethoprim-sulfamethoxazole (7.0%), and ciprofloxacin (6.7%)). CONCLUSION: To enhance the safety of agricultural products, it is necessary to frequently monitor the microbial quality of water.

Plant Pathology, 2019

Èlánek se zabývá otázkou transformace frazeologických jednotek, jejich aktualizací, vznikem neolo... more Èlánek se zabývá otázkou transformace frazeologických jednotek, jejich aktualizací, vznikem neologismù v umìleckém stylu. Souèasný jazyk, jak èeský, tak i ukrajinský, aktivnì reaguje na spoleèenské zmìny a aktuální problémy v rùzných oblastech spoleèenského života, což se projevuje v urèité míøe i ve frazeologii, kde vznikají nové jednotky-frazeologické neologismy. Pøíklady nìkterých strukturnì sémantických zmìn frazeologismù a vznik autorských okazionalizmù jsou proanalyzovány na pøíkladu knihy Evy Hauserové Noc v Mejdlovarnì. Pøeklad do ukrajinštiny a porovnání ekvivalentnosti potvrzuje teorii, že frazeologizmy a stejnì tak i frazeologické neologismy nejsou vždy jednoznaènì èi snadno transponovatelné do jazyka jiného. Dané bádání otevírá perspektivy pro další studium a analýzu èeských frazeologických neologismù a jejich pøeklad do ukrajinštiny. Z didaktického hlediska umístìní do výuky frazeologizmù a neofrazeologizmù rozhodnì oživuje studium cizího, v našem pøípadì èeského, jazyka, obohacuje lexikální zásobu i lingvokulturní znalosti studentù, rozšiøuje jejich komunikativní možnosti, èímž jim umožòuje poznat ve vší hloubce krásu èeského jazyka. Klíèová slova: modifikace frazeologických jednotek, transformace frazeologizmù, individuální autorské aktualizace frazémù, okazionalismy, frazeologické neologismy. ФРАЗЕОЛОГІЧНІ НЕОЛОГІЗМИ Й ОКАЗІОНАЛІЗМИ В СУЧАСНІЙ ЧЕСЬКІЙ ЛІТЕРАТУРІ (на прикладі твору Є. Гаусерової "Ніч у Миловарні") ГАРБУЗОВА Радка аспірант Київський національний лінгвістичний університет

Mycobiology, 2019

Fungi produce various secondary metabolites that have beneficial and harmful effects on other org... more Fungi produce various secondary metabolites that have beneficial and harmful effects on other organisms. Those bioactive metabolites have been explored as potential medicinal and antimicrobial resources. However, the activities of the culture filtrate (CF) and metabolites of whiterot fungus (Schizophyllum commune) have been underexplored. In this study, we assayed the antimicrobial activities of CF obtained from white-rot fungus against various plant pathogens and evaluated its efficacy for controlling anthracnose and gray mold in pepper plants. The CF inhibited the mycelial growth of various fungal plant pathogens, but not of bacterial pathogens. Diluted concentrations of CF significantly suppressed the severity of anthracnose and gray mold in pepper fruits. Furthermore, the incidence of anthracnose in field conditions was reduced by treatment with a 12.5% dilution of CF. The active compound responsible for the antifungal and disease control activity was identified and verified as schizostatin. Our results indicate that the CF of white-rot fungus can be used as an eco-friendly natural product against fungal plant pathogens. Moreover, the compound, schizostatin could be used as a biochemical resource or precursor for development as a pesticide. To the best of our knowledge, this is the first report on the control of plant diseases using CF and active compound from white-rot fungus. We discussed the controversial antagonistic activity of schizostatin and believe that the CF of white-rot fungus or its active compound, schizostatin, could be used as a biochemical pesticide against fungal diseases such as anthracnose and gray mold in many vegetables.

The plant pathology journal, 2016

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic ... more Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (≥ 10(6) cfu/ml) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (ΦPSII) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII (Fv/Fm) was altered well after symptom development. Visible/near infrared and chlorophyll fluores...

European Journal of Plant Pathology, 2017

Increasing evidence suggests that the interactions between plant and pathogen are influenced by l... more Increasing evidence suggests that the interactions between plant and pathogen are influenced by light perception of both organisms. In our previous study, green light decreased disease severity in tomato plants in response to Pseudomonas cichoriiJBC1 (PcJBC1) infection via induction of disease resistance-related genes. However, the influence of green light on gene expression and metabolism of PcJBC1 has not been explored. In this study, we cultured PcJBC1 in hrp-inducing minimal media (MM) under green light and dark condition, and analyzed the expression of genes, which are important in pathogenicity/virulence and epiphytic survival by real-time PCR (qPCR). Although no significant changes were observed in the expression of type 3 secretion system (T3SS)- and flagellar-related genes in response to green light, genes for the production of phytotoxic lipopeptides and siderophores were significantly reduced by green light. In addition, the phytotoxic lipopeptide and siderophore production in the culture supernatant was consistent with the results of gene expression. Furthermore, we compared the whole transcriptomes of PcJBC1 grown in MM under green light and dark condition. Among 243 differentially expressed genes (>2-fold change), the photoreceptor genes, bacteriophytochrome (bphP) and heme-oxygenase (bphO) were significantly up-regulated, whereas genes involved in the type 1 secretion system (T1SS), type 6 secretion system (T6SS), phytotoxic lipopeptides, and iron acquisition were profoundly repressed under green light. Corresponding to qPCR analysis, the RNA-seq results also showed no significant alteration in the T3SS- and flagellar-related genes. Overall, our results suggest that green light perceived by PcJBC1 plays a key role in diverse physiological responses that might affect this pathogen’s epiphytic survival. The receptor and signaling network involved in green light perception should be identified in further investigation.

Korean Journal of Environmental Agriculture

BACKGROUND: Contaminated water was a major source of food-borne pathogens in various recent fresh... more BACKGROUND: Contaminated water was a major source of food-borne pathogens in various recent fresh producerelated outbreaks. This study was conducted to investigate the microbial contamination level and correlations between the level of sanitary indicator bacteria and the detection ratio of pathogens in agricultural water by logistic regression analysis. METHODS AND RESULTS: Agricultural water was collected from 457 sites including surface water (n=300 sites) and groundwater (n=157 sites) in South Korea from 2018 to 2020. Sanitary indicator bacteria (total coliform, fecal coliform, and Escherichia coli) and food-borne pathogens (pathogenic E. coli, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were analyzed. In surface water, the coliform, fecal coliform, and E. coli were 3.27±0.89 log CFU/100 mL, 1.90±1.19 log CFU/100 mL, and 1.39±1.26 log CFU/100 mL, respectively. For groundwater, three kinds of sanitary indicators ranged in the level from 0.09-0.57 log CFU/100 mL. Pathogenic E. coli, Salmonella and Listeria monocytogenes were detected from 3%-site, 1.5%site, and 0.6%-site water samples, respectively. According to the results of correlations between the level of sanitary indicator bacteria and the detection ratio of pathogens by logistic regression analysis, the probability of pathogen detection increased individually by 1.45 and 1.34 times as each total coliform and E. coli concentration increased by 1 log CFU/100mL. The accuracy of the model was 70.4%, and sensitivity and specificity were 81.5% and 51.7%, respectively. CONCLUSION(S): The results indicate the need to manage the microbial risk of agricultural water to enhance the safety of fresh produce. In addition, logistic regression analysis is useful to analyze the correlation between the level of sanitary indicator bacteria and the detection ratio of pathogens in agricultural water.

This study aimed to establish appropriate conditions for the washing and storage of radish microg... more This study aimed to establish appropriate conditions for the washing and storage of radish microgreens by evaluating the effect of a sodium hypochlorite (NaOCl) wash on the growth of Escherichia coli and Listeria monocytogenes. Sodium hypochlorite (50, 100, 150 and 200 mg/L) was added to wash water and radish microgreens were treated for 5, 10, 15, 20, 25 and 30 min. Treatment with NaOCl (150 mg/L, 5 min) significantly reduced (2.3 log CFU/g) the populations of both bacteria (p<0.05). After washing, the levels of bacteria in NaOCl treated radish microgreens was evaluated during storage at 4°C, 10°C, 15°C and 20°C for 3 days. The growths of E. coli and L. monocytogenes increased rapidly at temperatures over 15°C and 10°C respectively, from day 1. We believed that NaOCl treatmentinduced injuries may have caused the release of exudate on microgreen surfaces, which could have facilitated the growth of the pathogens at temperatures >10°C. To validate this hypothesis, we inoculated ...

The Plant Pathology Journal

Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However,... more Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from...

Journal of Food Hygiene and Safety

Listeria monocytogenes (L. monocytogenes) was responsible for several recall cases owing to its i... more Listeria monocytogenes (L. monocytogenes) was responsible for several recall cases owing to its incidence in mushrooms exported from the Republic of Korea. In this study, we investigated the survival of L. monocytogenes in enoki mushroom (Flammulina velutipes) at different temperatures and the antilisterial effect of its organic acids. Enoki mushrooms were innoculated with L. monocytogenes (initial concentration 4.5 log CFU/g) and stored at 1-35 o C, No growth of L. monocytogenes in enoki mushrooms was observed at 1 o C for 30 days. 3.0 log CFU/ g growth of L. monocytogenes was also achieved after 36 h and 24 h at 30 o C and 35 o C, respectively. To evaluate the antilisterial effect of the organic acids (acetic acid, lactic acid, malic acid), enoki mushrooms were treated with 1-3% of each acid for 10-30 min. The efficacy of malic acid and lactic acid was significantly higher than that of acetic acid. Over 3.0 log reductions were observed when L. monocytogenes in enoki mushrooms was immersed in 3% lactic acid and malic acid over 10 minutes or more. Therefore, it is necessary to keep enoki mushrooms at 1 o C during the export process and treat them with 3% lactic acid and malic acid for 10 min prior to consumption.

Foods

Contamination by Listeria monocytogenes in packaged produce is a major concern. The purpose of th... more Contamination by Listeria monocytogenes in packaged produce is a major concern. The purpose of this study was to find natural and affordable sanitizers to reduce L. monocytogenes contamination in agricultural products. Organic acids, ultraviolet-C (UV-C), and ethanol were analyzed either alone or in combination to assess their ability to reduce L. monocytogenes population in radish, oriental melon, and carrot samples. In radish samples, 3% malic acid combined with UV-C at a dosage of 144 mj/cm2 significantly reduced (>4 log CFU/g) the population of L. monocytogenes (1.44 ± 0.5) compared to the control sample (5.14 ± 0.09). In the case of the melon samples, exposure to UV-C at a dosage of 144 mj/cm2 combined with 3% lactic acid (2.73 ± 0.75) or 50% ethanol (2.30 ± 0.01) was effective against L. monocytogenes compared to the control sample (5.10 ± 0.19). In carrot samples, 3% lactic acid combined with 144 mj/cm2 dosage UV-C reduced L. monocytogenes population (4.48 ± 0.25) more tha...

Journal of Food Hygiene and Safety

This study was undertaken to compare the efficacy of different sample preparation (stomaching, pu... more This study was undertaken to compare the efficacy of different sample preparation (stomaching, pulsifying, and sonication) and DNA extraction methods (boiling and commercial kit) for detection of enterotoxinproducing Clostridium perfringens from produce by polymerase chain reaction (PCR). Each produce type was inoculated at concentrations of 10 2 , 10 3 , 10 4 , 10 5 , 10 6 , and 10 7 spores/g. Produce inoculated with spores was treated with three sample preparation methods, and DNA was extracted by boiling method and a commercial kit, followed by PCR. The detection limit of stomached samples was lower than that of pummeled and sonicated samples by 10-100 times. Moreover, the DNA extraction efficiency of the commercial kit was found to be superior to that of boiling. In particular, the PCR efficiency of cherry tomato and perilla leaf samples was greatly affected by sample preparation and DNA extraction method. These data suggest that DNA extraction with a commercial kit after pulsification is an optimum sample preparation method for detection of C. perfringens by PCR.