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The whole genome sequence of Lactiplantibacillus plantarum DJF10, isolated from Korean raw milk, is reported, along with its genomic analysis of probiotics and safety features. The genome consists of 29 contigs with a total length of 3,385,113 bp and a GC content of 44.3%. The average nucleotide identity and whole genome phylogenetic analysis showed the strain belongs to Lactiplantibacillus plantarum with 99% identity. Genome annotation using Prokka predicted a total of 3235 genes, including 3168 protein-coding sequences (CDS), 59 tRNAs, 7 rRNAs and 1 tmRNA. The functional annotation results by EggNOG and KEGG showed a high number of genes associated with genetic information and processing, transport and metabolism, suggesting the strain's ability to adapt to several environments. Various genes conferring probiotic characteristics, including genes related to stress adaptation to the gastrointestinal tract, biosynthesis of vitamins, cell adhesion and production of bacteriocins, were identified. The CAZyme analysis detected 98 genes distributed under five CAZymes classes. In addition, several genes encoding carbohydrate transport and metabolism were identified. The genome also revealed the presence of insertion sequences, genomic islands, phage regions, CRISPR-cas regions, and the absence of virulence and toxin genes. However, the presence of hemolysin and antibiotic-resistance-related genes detected in the KEGG search needs further experimental validation to confirm the safety of the strain. The presence of two bacteriocin clusters, sactipeptide and plantaricin J, as detected by the BAGEL 4 webserver, confer the higher antimicrobial potential of DJF10. Altogether, the analyses in this study performed highlight this strain's functional characteristics. However, further in vitro and in vivo studies are required on the safety assurance and potential application of L. plantarum DJF10 as a probiotic agent.
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Bacteriocinas , Lactobacillus plantarum , Animais , Lactobacillus plantarum/metabolismo , Genoma Bacteriano , Filogenia , Leite , Bacteriocinas/metabolismo , Antibacterianos/metabolismo , República da CoreiaRESUMO
BACKGROUND: Cinnamoyl esterase (CE) can release antioxidant phenolic acids from its non-digestible ester-linked form. Fermentation using CE-producing lactic acid bacteria (LAB) can be useful in the food industry because of its ability to produce bioactive compounds and antibacterial metabolites. The purpose of this study was to confirm the food applicability of LAB with CE-producing ability and broad-spectrum antibacterial activity. RESULTS: Among the 219 bacterial strains identified in infant feces, five Lactobacillus gasseri and six Limosilactobacillus fermentum with a high CE activity were isolated. The survival rate of all selected LABs was > 95% at pH 2.5 for 3 h and > 70% when treated with 0.3% bile salt for 4 h. Moreover, cell-free supernatants of all strains strongly inhibited five food-borne bacterial pathogens (Listeria monocytogenes, Salmonella enterica, Escherichia coli O157:H7, Bacillus cereus, and Staphylococcus aureus) and three toxin-producing fungal pathogens (Aspergillus niger, Penicillium sp., and Fusarium oxysporum). To improve phenolic acid content and rice bran preservation, Limosilactobacillus fermentum J2 with the strongest CE activity and Lactobacillus gasseri N2 with the strongest antibacterial activity were used in rice bran fermentation, respectively. FRB-J2 (fermented rice bran with Limosilactobacillus fermentum J2) and FRB-N2 (fermented rice bran with Lactobacillus gasseri N2) significantly increased caffeic acid and ferulic acid (P < 0.01). FRB-J2 and FRB-N2 artificially inoculated with F. oxysporum showed no visible fungal growth during the test period (21 days). CONCLUSION: Fermentation by Limosilactobacillus fermentum J2 and Lactobacillus gasseri N2 can help extend the shelf life of rice bran-based products and produce bioactive compounds. © 2021 Society of Chemical Industry.
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Anti-Infecciosos , Alimentos Fermentados , Lactobacillus gasseri , Limosilactobacillus fermentum , Oryza , Antibacterianos/farmacologia , Esterases , Fermentação , Alimentos Fermentados/microbiologia , Oryza/microbiologiaRESUMO
As a representative colorimetic biosnesor, paper-based LFSA have emerged as a promising and robust tool that can easily and instansly detect the presence of target biological components in food sample. Recently, LFSAs have gained a considerable attention as an alternative method for rapid diagnosis of foodborne pathogens to the conventional culture-based assays such as plate counting and PCR. One major drawback of the current LFSAs for the detection of pathogenic bacteria is the low sensitivity, limiting its practical applications in POCT. Not like many other protein-based biomarkers that are present in nM or pM range, the number of pathogenic bacteria that cause disease can be as low as few CFU/ml. Here, we review current advances in LFSAs for the detection of pathogenic bacteria in terms of chromatic agents and analyte types. Furthermore, recent approaches for signal enhancement and modifications of the LFSA architecture for multiplex detection of pathogenic bacteria are included in this review, together with the advantages and limitations of each techniques. Finally, the technological challenges and future prospect of LFSA-based POCT for the detection of pathogenic bacteria are discussed.
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Bactérias/isolamento & purificação , Técnicas Biossensoriais , Contaminação de Alimentos/análise , Microbiologia de Alimentos/métodos , Colorimetria/instrumentação , PapelRESUMO
A colorimetric polydiacetylene (PDA) paper strip sensor that can specifically recognize Bacillus thuringiensis (BT) HD-73 spores is described in this work. The target-specific aptamer was combined with PDA, and the aptamer-conjugated PDA vesicles were then coated on polyvinylidene fluoride (PVDF) paper strips by a simple solvent evaporation method. The PDA-aptamer paper strips can be used to detect the target without any pre-treatment. Using the paper strip, the presence of BT spores is directly observable by the naked eye based on the unique blue-to-red color transition of the PDA. Quantitative studies using the paper strip were also carried out by analyzing the color transitions of the PDA. The specificity of this PDA sensor was verified with a high concentration of Escherichia coli, and no discernable change was observed. The observable color change in the paper strip occurs in less than 1 h, and the limit of detection is 3 × 107 CFU/mL, much below the level harmful to humans. The PDA-based paper sensor, developed in this work, does not require a separate power or detection device, making the sensor strip highly transportable and suitable for spore analysis anytime and anywhere. Moreover, this paper sensor platform is easily fabricated, can be adapted to other targets, is highly portable, and is highly specific for the detection of BT spores.
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Bacillus thuringiensis/isolamento & purificação , Técnicas Biossensoriais , Colorimetria , Esporos Bacterianos/isolamento & purificação , Polímero PoliacetilênicoRESUMO
OBJECTIVE: This study was conducted to determine the composition and diversity of the fungal flora at various control points in cheese ripening rooms of 10 dairy farms from six different provinces in the Republic of Korea. METHODS: Floor, wall, cheese board, room air, cheese rind and core were sampled from cheese ripening rooms of ten different dairy farms. The molds were enumerated using YM petrifilm, while isolation was done on yeast extract glucose chloramphenicol agar plates. Morphologically distinct isolates were identified using sequencing of internal transcribed spacer region. RESULTS: The fungal counts in 8 out of 10 dairy farms were out of acceptable range, as per hazard analysis critical control point regulation. A total of 986 fungal isolates identified and assigned to the phyla Ascomycota (14 genera) and Basidiomycota (3 genera). Of these Penicillium, Aspergillus, and Cladosporium were the most diverse and predominant. The cheese ripening rooms was overrepresented in 9 farms by Penicillium (76%), while Aspergillusin a single farm. Among 39 species, the prominent members were Penicillium commune, P. oxalicum, P. echinulatum, and Aspergillus versicolor. Most of the mold species detected on surfaces were the same found in the indoor air of cheese ripening rooms. CONCLUSION: The environment of cheese ripening rooms persuades a favourable niche for mold growth. The fungal diversity in the dairy farms were greatly influenced by several factors (exterior atmosphere, working personnel etc.,) and their proportion varied from one to another. Proper management of hygienic and production practices and air filtration system would be effective to eradicate contamination in cheese processing industries.
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The resident bacteria of the gastrointestinal tract (GIT) and the behaviour of these microbes have been poorly characterised in elk as compared to other ruminant animal species such as sheep and cattle. In addition, most microbial community studies of deer gut have focused on rumen or faeces, while other parts of the GIT such as the small and large intestine have received little attention. To address this issue, the present study investigated the diversity of the GIT bacterial community in elk (Cervus canadensis) by 16S rRNA pyrosequencing analysis. Eight distinct GIT segments including the stomach (rumen, omasum, and abomasum), small intestine (duodenum and jejunum), and large intestine (cecum, colon, and rectum) obtained from four elks were examined. We found that bacterial richness and diversity were higher in the stomach and large intestine than in the small intestine (P < 0.05). A total of 733 genera belonging to 26 phyla were distributed throughout elk GITs, with Firmicutes, Bacteroidetes, and Proteobacteria identified as the predominant phyla. In addition, there was spatial heterogeneity in the composition, diversity, and species abundance of microbiota in the GIT (P < 0.0001). To the best of our knowledge, this is the first study to characterise bacterial communities from eight GIT regions of elk by 16S rRNA pyrosequencing.
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Bactérias/isolamento & purificação , Cervos/microbiologia , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Ceco/microbiologia , Colo/microbiologia , DNA Bacteriano/genética , Fezes/microbiologia , Filogenia , RNA Ribossômico 16S/genética , Rúmen/microbiologiaRESUMO
A repetitive sequence-based polymerase chain reaction (rep-PCR) technique utilizing a semiautomated system, namely DiversiLab, was applied to determine the genotypes of Staphylococcus aureus and Bacillus cereus obtained from slaughterhouses. Twenty-four S. aureus and 16 B. cereus isolates from pigs and Hanwoo cattle from three slaughterhouses were used to create a DNA fingerprint library with the system software. Scatterplots demonstrated that rep-PCR groupings of S. aureus isolates were in good agreement with their origins. Specifically, linked rep-PCR profiles were observed for S. aureus isolates recovered from the same slaughterhouse, and higher genetic similarities were found among strains isolated from adjacent regions. All S. aureus isolates except one (ID: A-Hanwoo-9) from slaughterhouse "A" clustered with the three S. aureus reference strains, Korea Culture Center of Microorganisms (KCCM) 41291, KCCM 12214, and Culture Collection of Antimicrobial Resistant Microbes (CCARM) 3A007 (similarity values >95%). Moreover, most isolates obtained from slaughterhouse "B" clustered with S. aureus KCCM 11335 and KCCM 41331, and two isolates from slaughterhouse "C" clustered with CCARM 0027. Therefore, for this species, genotypic characteristics of regional isolates can be used to track the pathway of contamination. In contrast, B. cereus isolates showed high genetic diversity and could not be clustered with any specific group. Collectively, this system is useful for analyzing genetic diversity and is a rapid and reproducible typing method; however, there is a need to develop rep-PCR libraries for its use as a rapid identification method.
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Matadouros , Bacillus cereus/classificação , Bovinos/microbiologia , Reação em Cadeia da Polimerase/métodos , Staphylococcus aureus/classificação , Suínos/microbiologia , Animais , Bacillus cereus/genética , Bacillus cereus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Impressões Digitais de DNA , Doenças Transmitidas por Alimentos/microbiologia , Genótipo , Técnicas de Genotipagem , Humanos , Carne/microbiologia , Sequências Repetitivas de Ácido Nucleico , República da Coreia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificaçãoRESUMO
OBJECTIVE: The objective of this study was to evaluate the effect of combinations of NaNO2 and NaCl concentrations on Listeria monocytogenes (L. monocytogenes) growth in emulsion-type sausage. METHODS: Emulsion-type sausages formulated with different combinations of NaNO2 (0 and 10 ppm) and NaCl (1.00%, 1.25%, and 1.50%) were inoculated with a five-strain L. monocytogenes mixture, and stored at 4°C, 10°C, and 15°C, under aerobic or vacuum conditions. L. monocytogenes cell counts were measured at appropriate intervals, and kinetic parameters such as growth rate and lag phase duration (LPD) were calculated using the modified Gompertz model. RESULTS: Growth rates increased (0.004 to 0.079 Log colony-forming unit [CFU]/g/h) as storage temperature increased, but LPD decreased (445.11 to 8.35 h) as storage temperature and NaCl concentration increased. The effect of combinations of NaCl and low-NaNO2 on L. monocytogenes growth was not observed at 4°C and 10°C, but it was observed at 15°C, regardless of atmospheric conditions. CONCLUSION: These results indicate that low concentrations of NaNO2 and NaCl in emulsion-type sausage may not be sufficient to prevent L. monocytogenes growth, regardless of whether they are vacuum-packaged and stored at low temperatures. Therefore, additional techniques are necessary for L. monocytogenes control in the product.
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Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) coupled with stuffer-free multiplex ligation-dependent probe amplification (MLPA) was developed to identify 13 species of foodborne pathogens simultaneously. Species-specific MLPA probes were designed for nine of these species. These probes were targeted to the groEL, glyA, MMS, tuf, inv, ipaH, nuc, vvh, and 16S rRNA genes, which corresponded to Bacillus cereus, Campylobacter coli, Cronobacter sakazakii, Enterococcus spp., Salmonella spp., Shigella spp., Staphylococcus aureus, Vibrio vulnificus, and Yersinia enterocolitica, respectively. MLPA probes that had been previously developed by our laboratory were used for the other four species (Campylobacter jejuni, Clostridium perfringens, Escherichia coli O157:H7, and Listeria monocytogenes). The CE-SSCP method was optimized to identify all 13 foodborne microbes simultaneously in a single electrogram, in which 50-500 pg genomic DNA was detected per microbe. Twelve species were detected from animal-derived food samples (specifically, milk and sliced ham) that had been artificially inoculated with 12 of the foodborne pathogens, excluding V. vulnificus, which is not usually associated with animal foods. The method developed here could be used as an early warning system for outbreaks of foodborne diseases associated with animal-derived foods in the food industry.
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DNA Bacteriano/isolamento & purificação , Inspeção de Alimentos/métodos , Doenças Transmitidas por Alimentos/microbiologia , Bactérias Gram-Negativas/classificação , Bactérias Gram-Positivas/classificação , Tipagem Molecular/métodos , Polimorfismo Conformacional de Fita Simples , Animais , Bovinos , Sondas de DNA/análise , Sondas de DNA/metabolismo , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Eletroforese Capilar , Marcadores Genéticos , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Positivas/genética , Bactérias Gram-Positivas/isolamento & purificação , Humanos , Limite de Detecção , Carne/microbiologia , Leite/microbiologia , Reação em Cadeia da Polimerase Multiplex , Reprodutibilidade dos Testes , República da Coreia , Sus scrofaRESUMO
This study introduces multifunctional lipid nanoparticles (LNPs), mimicking the structure and compositions of low-density lipoproteins, for the tumor-targeted co-delivery of anti-cancer drugs and superparamagnetic nanocrystals. Paclitaxel (4.7 wt%) and iron oxide nanocrystals (6.8 wt%, 11 nm in diameter) are co-encapsulated within folate-functionalized LNPs, which contain a cluster of nanocrystals with an overall diameter of about 170 nm and a zeta potential of about -40 mV. The folate-functionalized LNPs enable the targeted detection of MCF-7, human breast adenocarcinoma expressing folate receptors, in T2 -weighted magnetic resonance images as well as the efficient intracellular delivery of paclitaxel. Paclitaxel-free LNPs show no significant cytotoxicity up to 0.2 mg mL(-1) , indicating the excellent biocompatibility of the LNPs for intracellular drug delivery applications. The targeted anti-tumor activities of the LNPs in a mouse tumor model suggest that the low-density lipoprotein-mimetic LNPs can be an effective theranostic platform with excellent biocompatibility for the tumor-targeted co-delivery of various anti-cancer agents.
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Lipoproteínas LDL/administração & dosagem , Nanopartículas , Neoplasias/terapia , Animais , Ciclo Celular , Humanos , Células MCF-7 , Imageamento por Ressonância Magnética , Camundongos , Microscopia de Força Atômica , Microscopia Eletrônica de TransmissãoRESUMO
A Gram-stain-positive, aerobic, endospore-forming, moderately halophilic rod, designated strain R1(T), was isolated from rice husks and subjected to a taxonomic study using a polyphasic approach. Strain R1(T) produced spherical or ellipsoidal endospores at a subterminal position in swollen sporangia, and was catalase- and oxidase-positive. The isolate grew optimally at 37 °C and pH 6.0-7.0, and could grow in the presence of up to 9% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R1(T) belongs to the genus Bacillus. The closest relatives of strain R1(T) were Bacillus subtilis subsp. subtilis NCIB 3610(T), Bacillus aquimaris TF-12(T), and Bacillus marisflavi TF-11(T), with 16S rRNA gene sequence similarities of 96.0%, 98.4%, and 98.7%, respectively. DNA-DNA relatedness values between the isolate and the reference strains were ≤42±3%. The predominant menaquinones were MK-5 (50%) and MK-7 (50%). The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylethanolamine. The major cellular fatty acids were iso-C(15â:â0) (48.6%) and anteiso-C(15â:â0) (20.6%), and the cell-wall diamino acid was meso-diaminopimelic acid. On the basis of 16S rRNA gene sequence analyses and chemotaxonomic and phenotypic characteristics, it is concluded that strain R1(T) represents a novel species of the genus Bacillus, for which we propose the name Bacillus oryzaecorticis sp. nov. The type strain is R1(T) (â=âKACC 17217(T)â=âKCCM 90231(T)â=âJCM 19602(T)).
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Bacillus/classificação , Oryza/microbiologia , Filogenia , Bacillus/genética , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Pigmentação , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA , Vitamina K 2/químicaRESUMO
We introduce shell cross-linked protein/quantum dot (QD) hybrid nanocapsules as a serum-stable systemic delivery nanocarrier for tumor-targeted in vivo bio-imaging applications. Highly luminescent, heavy-metal-free Cu0.3InS2/ZnS (CIS/ZnS) core-shell QDs are synthesized and mixed with amine-reactive six-armed poly(ethylene glycol) (PEG) in dichloromethane. Emulsification in an aqueous solution containing human serum albumin (HSA) results in shell cross-linked nanocapsules incorporating CIS/ZnS QDs, exhibiting high luminescence and excellent dispersion stability in a serum-containing medium. Folic acid is introduced as a tumor-targeting ligand. The feasibility of tumor-targeted in vivo bio-imaging is demonstrated by measuring the fluorescence intensity of several major organs and tumor tissue after an intravenous tail vein injection of the nanocapsules into nude mice. The cytotoxicity of the QD-loaded HSA-PEG nanocapsules is also examined in several types of cells. Our results show that the cellular uptake of the QDs is critical for cytotoxicity. Moreover, a significantly lower level of cell death is observed in the CIS/ZnS QDs compared to nanocapsules loaded with cadmium-based QDs. This study suggests that the systemic tumor targeting of heavy-metal-free QDs using shell cross-linked HSA-PEG hybrid nanocapsules is a promising route for in vivo tumor diagnosis with reduced non-specific toxicity.
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The success of antimicrobial therapy depends on effective prescription of antibiotics. Assessment of clinical isolates using rapid antimicrobial susceptibility tests allows effective microbiological therapy to be commenced in a timely manner. However, conventional antimicrobial susceptibility testing is time-consuming and laborious. In the present study, we employed stuffer-free multiplex ligation-dependent probe amplification (MLPA) coupled with analysis of single-strand conformation polymorphisms, via high-resolution CE, to develop a multiplex antibiotic susceptibility test. Using this method, parallel analysis of specific genetic markers was employed to determine minimal inhibitory concentration values. The values derived using the stuffer-free MLPA method agreed with those estimated using a conventional broth dilution method. These findings indicate that the stuffer-free MLPA-based approach is a viable alternative to the conventional method.
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Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Eletroforese Capilar/métodos , Testes de Sensibilidade Microbiana/métodos , Reação em Cadeia da Polimerase Multiplex/métodos , Bactérias/genética , Bactérias/isolamento & purificação , DNA Bacteriano/análise , DNA Bacteriano/genética , Polimorfismo Conformacional de Fita SimplesRESUMO
Bacteriocins may be used as natural preservatives and antibiotic substitutes in various foods. However, the multistep purification process of bacteriocins results in high production costs, which is an obstacle to their commercial use and consumer accessibility. In this study, a bacteriocin-like inhibitory substance (BLIS) from Bacillus spp. isolated from Korean fermented foods was partially purified using the aqueous two-phase system (ATPS). The maximum activity of the BLIS was achieved for ATPS composed of PEG 1000 (15% [w/w])/ammonium sulfate (20% [w/w])/sodium chloride (2% [w/w]), which caused BLIS activity to increase by 3 times with a 99% recovery rate. In particular, B. amyloliquefaciens Y138-6 BLIS exhibited broad antibacterial activity, high resistance to acid-base stress, and excellent thermal stability. This antibacterial substance inhibited the growth of aerobic bacteria and fungi on the walls of cheese and ripening rooms. These antibacterial properties have been shown to increase food safety and have the potential for use as biopreservatives. Moreover, considering that the execution of the ATPS requires only salts and PEG, it is a simple, environmentally friendly, and cost-effective process and may have industrial applications in the recovery of BLIS from fermentation broth.
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Sensitive multiplex detection methods for foodborne pathogens are important in controlling food safety, and detection of genetic markers is accepted to be one of the best tools for sensitive detection. Although CE technology offers great potential in terms of sensitive multiplex detection, the necessary amplification is confined to markers sharing common primers such as the 16S rRNA gene. For precise and sensitive detection, pathogen-specific genes are optimal markers. Although multiplex ligation-dependent probe amplification (MLPA) is appropriate for amplification of specific markers, the requirement for stuffers, to ensure length-dependent separation on CE, is a major obstacle in detection of foodborne pathogens. In the present study, we developed stuffer-free MLPA using high-resolution CE-SSCP to sensitively detect ten foodborne pathogens. The probe set for MLPA prior to CE-SSCP analysis was designed for species-specific detection. After careful optimization of each MLPA step, to ensure that CE-SSCP analysis was informative, we found that all ten pathogens could be reliably identified; the limits of detection were 0.5-5 pg of genomic DNA, and more than 100-fold increase could be quantitatively determined. Thus, MLPA-CE-SSCP is a sensitive and reliable technique for pathogen detection.
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Bactérias/isolamento & purificação , Eletroforese Capilar/métodos , Tipagem Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Polimorfismo Conformacional de Fita Simples , Bactérias/classificação , Bactérias/genética , Doenças Transmitidas por Alimentos/microbiologia , Limite de Detecção , Reprodutibilidade dos TestesRESUMO
The microbial community in fermented sausages plays an important role in determining their quality characteristics. The objective of this study was to investigate the correlation between microbial diversity and volatile compounds in dry-fermented sausages procured from different regions of Korea. Results from metagenomics analysis showed that Lactobacillus and Staphylococcus were the predominant bacterial genera, and Penicillium, Debaryomyces, and Candida were the predominant fungal genera. Twelve volatile compounds were detected using an electronic nose. Leuconostoc exhibited a positive correlation with esters and volatile flavor, whereas Debaryomyces, Aspergillus, Mucor, and Rhodotorula exhibited a negative correlation with methanethiol, thus revealing the involvement of the microorganisms in flavor formation. The results of this study may help in understanding the microbial diversity of dry-fermented sausages in Korea and provide a rationale and quality control guideline through potential correlation with volatile flavor analysis.
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Pig slaughterhouses harbor high humidity because of the necessary cleaning that takes place simultaneously with slaughter, which facilitates the existence of mold. Due to the enclosed space, there are several limitations to the control of mold growth with respect to cleaning, ventilation, and drying. In this study, the prevalence of fungi was investigated in four pig slaughterhouses in Korea. Four fungi (Aspergillus niger, Penicillium commune, Penicillium oxalicum, and Cladosporium cladosporioides) were detected with the highest frequency. These four strains were subjected to various treatments to reduce their growth. The fungi were inoculated onto stainless steel (SS) chips and treated with ultraviolet (UV)-C irradiation and hot water. Individual treatments with UV-C (15, 30, 90, 150, 300, and 600 mJ/cm2), and hot water (60, 65, 70, and 83°C) were performed to sanitize the SS chips. Simultaneous cleaning with 60°C hot water and more than 150 mJ/cm2 of UV-C reduced the fungal incidence by > 6.5 Log from 6.6-7.0 Log CFU/cm2 (initial count). Our results demonstrate that a combined treatment of UV-C and hot water is the most economical and convenient way to prevent microbiological contamination of small tools (such as knives and sharpeners) and steel surfaces in slaughterhouses.
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This study developed a simple and rapid strategic technique to detect ractopamine (chemical growth-promoting agent) in pork. Two highly sensitive and specific gold nanoparticle-based portable sensors, i.e., localized surface plasmon resonance (LSPR) sensors, and lateral flow immunoassay (LFIA) strips were developed to detect veterinary drug residues in food products, that have detrimental effects on humans. Optimization studies were conducted on several sensor devices to improve sensitivity. Each sensor comprised functionalized gold nanoparticles conjugated with ractopamine antibodies. The LSPR sensor chip achieved excellent detection sensitivity = 1.19 fg/mL and was advantageous for quantitative analysis due to its wide dynamic range. On the other hand, LFIA strips provided visual test confirmation and achieved 2.27 ng/mL detection sensitivity, significantly less sensitive than LSPR. The complementary sensors help overcome each other's shortcomings with both the techniques offering ease of use, affordability and rapid diagnosis. Thus, these sensors can be applied on-site for routine screening of harmful drug residues in pork meat. They also provide useful direction for advanced technologies to enhance assay performance for detecting various other food drug contaminants.
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Nanopartículas Metálicas , Carne de Porco , Carne Vermelha , Humanos , Animais , Suínos , Ressonância de Plasmônio de Superfície/métodos , Ouro/química , Nanopartículas Metálicas/química , Imunoensaio/métodosRESUMO
Enrofloxacin (ENR) is a veterinary antibiotic used to treat bacterial infections in livestock. It chiefly persists in foods and dairy products, which in turn pose severe risks to human health. Hence it is very important to detect the ENR in foods and dairy products to safeguard human health. Herein, we attempted to develop a single-step detection lateral flow immunochromatographic assay (LFIA) using gold nanoparticles (AuNPs) for the rapid and on-site detection of ENR in milk samples. An anti-enrofloxacin monoclonal antibody (ENR-Ab) was conjugated with AuNPs for the specific detection of ENR in milk samples. For sensitivity improvement, many optimization steps were conducted on LFIA test strips. The visual limit of detection (vLOD) was found to be 20 ng/ml with a cut-off value of 50 ng/ml in the milk samples. The obtained LOD and cut-off value were within the safety limit guidelines of the Ministry of food and drug safety, South Korea. The test strip showed negligible cross-reactivity with ENR analogs, and other components of antibiotics, this indicates the high specificity of the LFIA test strip towards ENR. The designed test strip showed good reliability. The visual test results can be seen within 10 min without the need for special equipment. Therefore, the test strip can be employed as a potential detection strategy for the qualitative on-site detection of enrofloxacin in milk samples.
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Lactic acid bacteria biofilms can be used to reduce foodborne pathogen contamination in the food industry. However, studies on growth inhibition of foodborne pathogens by inducing biofilm formation of antagonistic microorganisms on abiotic surfaces are rare. We developed a desiccation-tolerant antimicrobial probiotic biofilm. Lactobacillus sakei M129-1 and Pediococcus pentosaceus M132-2 isolated from fermented Korean foods were found to exhibit broad-spectrum antibacterial activity against Bacillus cereus, Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica. Their biofilm levels were significantly (p < 0.05) higher on stainless steel than on polyethylene or ceramic. Biofilms of both isolates showed significantly (p < 0.05) enhanced resistance against desiccation (exposure to 43% atmospheric relative humidity) as compared with the isolates not in the biofilm form. The antimicrobial activity of the isolates was sustained in dried biofilms on stainless steel surface; the initial number of foodborne pathogens (average 7.0 log CFU/mL), inoculated on stainless steel chips containing L. sakei M129-1 or P. pentosaceus M132-2 biofilm decreased to less than 1.0 log CFU within 48 h. The lactic acid bacteria antibacterial biofilms developed in this study may be applied to desiccated environmental surfaces in food-related environments to improve microbiological food safety.