Growth, biofilm formation, and motility of Listeria monocytogenes strains isolated from food and clinical samples located in Shanghai (China).

Listeria monocytogenes is a common foodborne pathogen that frequently causes global outbreaks. In this study, the growth characteristics, biofilm formation ability, motility ability and whole genome of 26 L. monocytogenes strains isolated from food and clinical samples in Shanghai (China) from 2020 to 2022 were analyzed. There are significant differences among isolates in terms of growth, biofilm formation, motility, and gene expression. Compared with other sequence type (ST) types, ST1930 type exhibited a significantly higher maximum growth rate, the ST8 type demonstrated a stronger biofilm formation ability, and the ST121 type displayed greater motility ability. Furthermore, ST121 exhibited significantly high mRNA expression levels compared with other ST types in virulence genes mpl, fbpA and fbpB, the quorum sensing gene luxS, starvation response regulation gene relA, and biofilm adhesion related gene bapL. Whole-genome sequencing (WGS) analyses indicated the isolates of lineage I were mostly derived from clinical, and the isolates of lineage II were mostly derived from food. The motility ability, along with the expression of genes associated with motility (motA and motB), exhibited a significantly higher level in lineage II compared with lineage I. The isolates from food exhibited significantly higher motility ability compared with isolates from clinical. By integrating growth, biofilm formation, motility phenotype with molecular and genotyping information, it is possible to enhance comprehension of the association between genes associated with these characteristics in L. monocytogenes.

Antibacterial Effect and Possible Mechanism of Sesamol against Foodborne Pathogens.

Food safety problems caused by foodborne pathogens have become a major public issue, and the search for efficient and safe bacteriostatic agents has gained attention. Sesamol (SE), a phenolic compound abundant in sesame oil, offers numerous health benefits and exhibits certain antibacterial properties. The purpose of this study was to evaluate the antibacterial effect and potential mechanisms of SE against representative foodborne pathogens, including Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Salmonella serovar Enteritidis. The results showed that SE significantly inhibited the growth of the five pathogenic bacteria in sterile saline and pasteurized milk by 2.16-4.16 log10 CFU/g within 48 h. The results of the minimum bactericidal concentration and time-kill assay showed that SE had a greater inhibitory effect on L. monocytogenes compared with other bacteria. Additionally, SE was found to alter the cell membranes' permeability in these bacteria, resulting in the release of intercellular proteins and DNA. A scanning electron microscopy analysis showed that exposure to SE resulted in significant changes in bacterial morphology, producing cell shrinkage and deformation. These findings suggest that SE could inhibit both Gram-negative and Gram-positive bacteria by interfering with the function and morphology of bacterial cells.

Recent advances on the formation, detection, resistance mechanism, and control technology of Listeria monocytogenes biofilm in food industry.

Listeria monocytogenes is an important foodborne pathogen that causes listeriosis, a severe and fatal condition. Biofilms are communities of microorganisms nested within a self-secreted extracellular polymeric substance, and they protect L. monocytogenes from environmental stresses. Biofilms, once formed, can lead to the persistence of L. monocytogenes in processing equipment and are therefore considered to be a major concern for the food industry. This paper briefly introduces the recent advancements on biofilm formation characteristics and detection methods, and focuses on analysis of the mechanism of L. monocytogenes biofilm resistance; Moreover, this paper also summarizes and discusses the existing different techniques of L. monocytogenes biofilm control according to the physical, chemical, biological, and combined strategies, to provide a theoretical reference to aid the choice of effective control technology in the food industry.

Prevalence, antibiotic resistance and molecular characterization of Staphylococcus aureus in ready-to-eat fruits and vegetables in Shanghai, China.

Staphylococcus aureus (S. aureus) is one of the foodborne pathogens. This study aimed to investigate the prevalence of S. aureus in ready-to-eat (RTE) fruits and vegetables in Shanghai, China. We evaluated antibiotic resistance patterns and genetic diversity of isolates through whole genome sequencing. Our findings demonstrated that out of 143 market samples, 47 (32.87%) tested positive for S. aureus, with the prevalence rates ranging from 10% to 57.14% among 12 types of RTE fruits and vegetables. Most isolates were resistant to trimethoprim-sulphamethoxazole, oxacillin, and ampicillin. We identified a total of 15 antibiotic resistance genes associated with resistance to 6 antibiotics, such as fosfomycin, fluoroquinolone, and ß-lactam. Adhesion genes and enterotoxin genes, including icaA, icaB, icaC, set, seg, and sec, were also identified. Seven multi-locus sequence types (MLST) were detected, two of which were novel (ST7208 and ST7986). Notably, ST705-t529 (34.04%) and ST6-t701 (27.79%) represented the predominant types of S. aureus. Furthermore, three of the isolates were confirmed to be methicillin-resistant S. aureus by mecA genes. Taken together, our results highlight the high prevalence of S. aureus in RTE fruits and vegetables, posing a potential threat to food safety, particularly due to its high level of antibiotic resistance.

[Advances in in vitro and in vivo models for Listeria monocytogenes placental infection].

Listeria monocytogenes is recognized as a significant foodborne pathogen, capable of causing listeriosis in humans, which is a global public health concern. This pathogen is particularly dangerous for pregnant women, as it can lead to invasive listeriosis in fetuses and neonates, posing a significant threat to both maternal and fetal health. Therefore, establishing suitable in vitro and in vivo models for L. monocytogenes placenta infection, as well as analyzing and exploring the infection process and its pathogenic mechanism, are important approaches to prevent and control L. monocytogenes infection in mothers and infants. In this study, we reviewed the in vitro and in vivo placental models used for studying the infection of L. monocytogenes in maternal and infant, summarized and discussed the advantages and limitations of each model, and explored the potential of in vitro cell models and organoids for the study of L. monocytogenes infection. This paper aims to support the study of the infection pathway and pathogenesis of listeriosis and provide scientific references for the prevention and control of L. monocytogenes infection.

Exposure of Salmonella enterica serovar 1,4,[5],12:i:- to benzalkonium chloride leads to acquired resistance to this disinfectant and antibiotics.

AIMS: Disinfectants such as benzalkonium chloride (BC), extensively used in animal farms and food-processing industries, contribute to the development of adaptive and cross-resistance in foodborne pathogens, posing a serious threat to food safety and human health. The purpose of this study is to explore whether continuous exposure of Salmonella enterica serovar 1,4,[5],12:i:- (S. 1,4,[5],12:i:-) to sublethal concentrations of BC could result in acquired resistance to this agent and other environmental stresses (e.g. antibiotics, heat, and acid). METHODS AND RESULTS: BC tolerance increased in all tested strains after exposure to gradually increasing concentrations of BC, with increases in minimum inhibitory concentrations between two and sixfold. The survival rate of BC-adapted strains was significantly (P < 0.05) higher than that of their wild-type (non-adapted) counterparts in lethal concentrations of BC. In addition, significant reductions (P < 0.05) in zeta potential were observed in BC-adapted strains compared to wild-type ones, indicating that a reduction in cell surface charge was a cause of adaptative resistance. More importantly, two BC-adapted strains exhibited increased antibiotic resistance to levofloxacin, ceftazidime, and tigecycline, while gene mutations (gyrA, parC) and antibiotic efflux-related genes (acrB, mdsA, mdsB) were detected by genomic sequencing analysis. Moreover, the tolerance of BC-adapted strains to heat (50, 55, and 60°C) and acid (pH 2.0, 2.5) was strain-dependent and condition-dependent. CONCLUSIONS: Repeated exposure to sublethal concentrations of BC could result in the emergence of BC- and antibiotic-resistant S. 1,4,[5],12:i:- strains.

Different cellular fatty acid pattern and gene expression of planktonic and biofilm state Listeria monocytogenes under nutritional stress.

Listeria monocytogenes is a Gram-positive bacterium frequently involved in food-borne disease outbreaks and is widely distributed in the food-processing environment. This work aims to depict the impact of nutrition deficiency on the survival strategy of L. monocytogenes both in planktonic and biofilm states. In the present study, cell characteristics (autoaggression, hydrophobicity and motility), membrane fatty acid composition of MRL300083 (Lm83) in the forms of planktonic and biofilm-associated cells cultured in TSB-YE and 10-fold dilutions of TSB-YE (DTSB-YE) were investigated. Additionally, the relative expression of related genes were also determined by RT-qPCR. It was observed that cell growth in different bacterial life modes under nutritional stress rendered the cells a distinct phenotype. The higher autoaggression (AAG) and motility of the planktonic cells in DTSB-YE is associated with better biofilm formation. An increased proportion of unsaturated fatty acid/saturated fatty acid (USFA/SFA) indicates more fluidic biophysical properties for cell membranes of L. monocytogenes in planktonic and biofilm cells in DTSB-YE. Biofilm cells produced a higher percentage of USFA and straight fatty acids than the corresponding planktonic cells. An appropriate degree of membrane fluidity is crucial for survival, and alteration of membrane lipids is an essential adaptive response. The adaptation of bacteria to stress is a multifactorial cellular process, the expression of flagella-related genes fliG, fliP, flgE and the two-component chemotactic system cheA/Y genes of planktonic cells in DTSB-YE significantly increased compared to that in TSB-YE (p < 0.05). This study provides new information on the role of the physiological adaptation and gene expression of L. monocytogenes for planktonic and biofilm growth under nutritional stress.

Antimicrobial function of yeast against pathogenic and spoilage microorganisms via either antagonism or encapsulation: A review.

Contaminations of pathogenic and spoilage microbes on foods are threatening food safety and quality, highlighting the importance of developing antimicrobial agents. According to different working mechanisms, the antimicrobial activities of yeast-based agents were summarized from two aspects: antagonism and encapsulation. Antagonistic yeasts are usually applied as biocontrol agents for the preservation of fruits and vegetables via inactivating spoilage microbes, usually phytopathogens. This review systematically summarized various species of antagonistic yeasts, potential combinations to improve the antimicrobial efficiency, and the antagonistic mechanisms. The wide applications of the antagonistic yeasts are significantly limited by undesirable antimicrobial efficiency, poor environmental resistance, and a narrow antimicrobial spectrum. Another strategy for achieving effective antimicrobial activity is to encapsulate various chemical antimicrobial agents into a yeast-based carrier that has been previously inactivated. This is accomplished by immersing the dead yeast cells with porous structure in an antimicrobial suspension and applying high vacuum pressure to allow the agents to diffuse inside the yeast cells. Typical antimicrobial agents encapsulated in the yeast carriers have been reviewed, including chlorine-based biocides, antimicrobial essential oils, and photosensitizers. Benefiting from the existence of the inactive yeast carrier, the antimicrobial efficiencies and functional durability of the encapsulated antimicrobial agents, such as chlorine-based agents, essential oils, and photosensitizers, are significantly improved compared with the unencapsulated ones.

A review of potential antibacterial activities of nisin against Listeria monocytogenes: the combined use of nisin shows more advantages than single use.

Listeria monocytogenes is a foodborne pathogen causing serious public health problems. Nisin is a natural antimicrobial agent produced by Lactococcus lactis and widely used in the food industry. However, the anti-L. monocytogenes efficiency of nisin might be decreased due to natural or acquired resistance of L. monocytogenes to nisin, or complexity of the food environment. The limitation of nisin as a bacteriostatic agent in food could be improved using a combination of methods. In this review, the physiochemical characteristics, species, bioengineered mutants, and antimicrobial mechanism of nisin are reviewed. Strategies of nisin combined with other antibacterial methods, including physical, chemical, and natural substances, and nanotechnology to enhance antibacterial effect are highlighted and discussed. Additionally, the antibacterial efficiency of nisin applied in real meat, dairy, and aquatic products is evaluated and analyzed. Among the various binding treatments, the combination with natural substances is more effective than the combination with physical and chemical methods. However, the combination of nisin and nanotechnology has more potential in terms of the impact on food quality.

Characterization of Listeria monocytogenes biofilm formation kinetics and biofilm transfer to cantaloupe surfaces.

Listeria monocytogenes biofilm is a consistent source of cross-contamination, both in housing storage and food processing environments. This study monitored the dynamic process of L. monocytogenes ST9 and ST87 biofilms, as well as their cross-contamination behaviors at various stages of formation. Scanning Electron Microscopy (SEM) captured the honeycomb-like structures and extracellular polymeric substances (EPS) during the biofilm formation. Confocal Laser Scanning Microscopy (CLSM) images illustrated that the ST87 strain formed a closed knitted chains network later than the ST9 strain. Moreover, structural parameters including bio-volume, mean thickness, porosity, and roughness could quantified the spatio-temporal differences of the biofilms. The transfer rates of biofilm cells to cantaloupes with the single contact had no significant difference at the initial adhesion, maturation, and dispersion stage (p > 0.05). Notably, the biofilm cells remained on the glass coupons when transferred to ten cantaloupe slices, indicating that biofilm cells transferred through cohesive failure. Meanwhile, the Logistic model could describe the transfer law of biofilm cells at different formation stages, as evaluated by Root Mean Square Error (RMSE) and R2adj. Additionally, the transfer rates were positively correlated with the hydrophobicity of L. monocytogenes ST87 biofilm cells measured by xylene. However, when the hydrophobicity of n-hexadecane was measured, the correlation was negative. This study illustrated the spatial and temporal differences during L. monocytogenes biofilms formation, and the transfer and residual of biofilm cells after a single and ten successive contacts at the specific stages. Our findings help in the quantitative microbiological risk assessment of fresh produce.

Potential antimicrobial activities of probiotics and their derivatives against Listeria monocytogenes in food field: A review.

Listeria monocytogenes is an important food-borne pathogen, which could be detected in food, environmental and clinical samples. It contaminates food in any of the stages during production, processing, and storage, resulting in potential food safety issues. Traditional physical and chemical methods are effective in inhibiting the growth of L. monocytogenes and extending the shelf life of foods, however, the application of these methods usually results in undesirable damage to food quality. Recently, biological-based antimicrobial methods have attracted numerous attention due to their promising antimicrobial effects and ability to maintain food quality. The application of probiotics, as one of the biological based antimicrobial methods, has been widely reported that could effectively inhibit the growth of L. monocytogenes. In this review, human listeriosis and the current contamination situation of L. monocytogenes in foods are summarized first. Then, the effects of probiotics on the growth, biofilm formation, and virulence of L. monocytogenes in foods are discussed. Furthermore, the inhibitory mechanisms of the probiotics and their metabolites against L. monocytogenes are highlighted. With a comprehensive understanding of the bacteriostatic effect of the probiotics, the latest applications of probiotics in dairy products, meat products, and fresh products are presented and discussed.

[Placenta-specific virulence factors involved in Listeria monocytogenes infection].

Listeria monocytogenes (LM) is a food-borne pathogen that can cause listeriosis. Pregnant women are main target population of listeriosis due to pregnancy-associated immune deficiency and unique intracellular infection ability of LM to non-phagocytic cells. LM can cross the placental barrier and cause significant harm to the fetus, including premature birth, miscarriage and even stillbirth. The role of placenta-specific virulence factors is particularly important for researchers to understand how it crosses the placental barrier and infects the fetus during LM infection. This review started by describing the listeriosis in pregnant women, followed by summarizing the advances in understanding the LM vertical transplacental infection and the mechanism of LM colonization in the placenta. Finally, recent advances in identifying placenta-specific virulence factors involved in LM infections were presented, with the aim to facilitate the control of LM transplacental infection and the improvement of food safety.

Biofilm Formation of Listeria monocytogenes and Pseudomonas aeruginosa in a Simulated Chicken Processing Environment.

This study aims to investigate the mono- and dual-species biofilm formation of Listeria monocytogenes and Pseudomonas aeruginosa incubated in different culture mediums, inoculum ratios, and incubation time. The planktonic cell population and motility were examined to understand the correlation with biofilm formation. The results showed that chicken juice significantly inhibited the biofilm formation of L. monocytogenes (p < 0.05). Pseudomonas aeruginosa was the dominant bacteria in the dual-species biofilm formation in the trypticase soy broth medium. The dynamic changes in biofilm formation were not consistent with the different culture conditions. The growth of planktonic L. monocytogenes and P. aeruginosa in the suspension was inconsistent with their growth in the biofilms. There was no significant correlation between motility and biofilm formation of L. monocytogenes and P. aeruginosa. Moreover, scanning electron microscopy (SEM) results revealed that the biofilm structure of L. monocytogenes was loose. At the same time, P. aeruginosa formed a relatively dense network in mono-species biofilms in an initial adhesion stage (24 h). SEM results also showed that P. aeruginosa was dominant in the dual-species biofilms. Overall, these results could provide a theoretical reference for preventing and controlling the biofilm formation of L. monocytogenes and P. aeruginosa in the food processing environment in the future.

Modelling the Adhesion and Biofilm Formation Boundary of Listeria monocytogenes ST9.

Listeria monocytogenes is a major foodborne pathogen that can adhere to or form a biofilm on food contact surfaces, depending on the environmental conditions. The purpose of this work is to determine the adhesion and biofilm formation boundaries for L. monocytogenes ST9 under the combination environments of temperature (5, 15, and 25 °C), NaCl concentration (0%, 3%, 6%, and 9% (w/v)) and pH (5.0, 6.0, 7.0, and 8.0). The probability models of adhesion and biofilm formation were built using the logistic regression. For adhesion, only the terms of linear T and NaCl are significant for L. monocytogenes ST9 (p < 0.05), whereas the terms of linear T, NaCl, and pH, and the interaction between T and pH were significant for biofilm formation (p < 0.05). By analyzing contour maps and their surface plots for two different states, we discovered that high temperature promoted adhesion and biofilm formation, whereas excessive NaCl concentration inhibited both of them. With a stringent threshold of 0.1667, the accuracy rate for identifying both adhesion/no-adhesion and biofilm formation/no-biofilm formation events were 0.929, indicating that the probability models are reasonably accurate in predicting the adhesion and biofilm formation boundary of L. monocytogenes ST9. The boundary model may provide a useful way for determining and further controlling L. monocytogenes adhesion and biofilm formation in various food processing environments.

Machine learning approach for predicting single cell lag time of Salmonella Enteritidis after heat and chlorine treatment.

The importance of single-cell variability is increasingly prominent with the developments in foodborne pathogens modeling. Traditional predictive microbiology model cannot accurately describe the growth behavior of small numbers of cells due to individual cell heterogeneity. The objective of the present study was to develop predictive models for single cell lag times of Salmonella Enteritidis after heat and chlorine treatment. A time-lapse microscopy method was employed to evaluate the single cell lag time by monitoring cell divisions. Four supervised machine learning algorithms including gradient boosting regression tree (GBRT), artificial neural network (ANN), random forest (RF), and support vector regression (SVR) were applied and compared. Results show that all four machine learning models have good predictive capabilities without an overfitting of the data. The ANN approach demonstrated superior prediction performance over other machine learning models (RMSE: 0.209, MAE: 0.135 and R2: 0.989). Furthermore, the SHapley Additive exPlanation (SHAP) measures were used to capture the influence of each feature on the model output, and results revealed that population lag times and sublethal injury rate have dominant impacts on the single cell lag time. Consequently, the findings generated from this study may be useful in managing the potential food safety risk caused by single cells of foodborne pathogens.

Lactiplantibacillus plantarum subsp. plantarum and Fructooligosaccharides Combination Inhibits the Growth, Adhesion, Invasion, and Virulence of Listeria monocytogenes.

Listeria monocytogenes is a foodborne pathogen responsible for many food outbreaks worldwide. This study aimed to investigate the single and combined effect of fructooligosaccharides (FOS) and Lactiplantibacillus plantarum subsp. plantarum CICC 6257 (L. plantarum) on the growth, adhesion, invasion, and virulence of gene expressions of Listeria monocytogenes 19112 serotype 4b (L. monocytogenes). Results showed that L. plantarum combined with 2% and 4% (w/v) FOS significantly (p < 0.05) inhibited the growth of L. monocytogenes (3-3.5 log10 CFU/mL reduction) at the incubation temperature of 10 °C and 25 °C. Under the same combination condition, the invasion rates of L. monocytogenes to Caco-2 and BeWo cells were reduced more than 90% compared to the result of the untreated group. After L. plantarum was combined with the 2% and 4% (w/v) FOS treatment, the gene expression of actin-based motility, sigma factor, internalin A, internalin B, positive regulatory factor A, and listeriolysin O significantly (p < 0.05) were reduced over 91%, 77%, 92%, 89%, 79%, and 79% compared to the result of the untreated group, respectively. The inhibition level of the L. plantarum and FOS combination against L. monocytogenes was higher than that of FOS or L. plantarum alone. Overall, these results indicated that the L. plantarum and FOS combination might be an effective formula against L. monocytogenes.

A Meta-Analysis and Systematic Review of Listeria monocytogenes Response to Sanitizer Treatments.

Listeria monocytogenes is a ubiquitous organism that can be found in food-related environments, and sanitizers commonly prevent and control it. The aim of this study is to perform a meta-analysis of L. monocytogenes response to sanitizer treatments. According to the principle of systematic review, we extracted 896 records on the mean log-reduction of L. monocytogenes from 84 publications as the dataset for this study. We applied a mixed-effects model to describe L. monocytogenes response to sanitizer treatment by considering sanitizer type, matrix type, biofilm status, sanitizer concentration, treatment time, and temperature. Based on the established model, we compared the response of L. monocytogenes under different hypothetical conditions using forest plots. The results showed that environmental factors (i.e., sanitizer concentration, temperature, and treatment time) affected the average log-reduction of L. monocytogenes (p < 0.05). L. monocytogenes generally exhibited strong resistance to citric acid and sodium hypochlorite but had low resistance to electrolyzed water. The planktonic cells of L. monocytogenes were less resistant to peracetic acid and sodium hypochlorite than the adherent and biofilm cells. Additionally, the physical and chemical properties of the contaminated or inoculated matrix or surface also influenced the sanitizer effectiveness. This review may contribute to increasing our knowledge of L. monocytogenes resistance to sanitizers and raising awareness of appropriate safety precautions.

The Prevalence and Epidemiology of Salmonella in Retail Raw Poultry Meat in China: A Systematic Review and Meta-Analysis.

Foodborne disease caused by Salmonella is an important public health concern worldwide. Animal-based food, especially poultry meat, is the main source of human salmonellosis. The objective of this study was to evaluate the prevalence and epidemiology of Salmonella contamination in raw poultry meat commercialized in China. Following the principle of systematic review, 98 sets of prevalence data were extracted from 74 publications conducted in 21 Chinese provincial regions. The random-effect model was constructed for subgrouping analysis by meat category, preservation type, and geographical location. The prevalence levels differed from high to low among raw poultry meat, including chicken, 26.4% (95% CI: 22.4-30.8%); pigeon, 22.6% (95% CI: 18.2-27.8%); duck, 10.1% (95% CI: 5.3-18.2%); and other poultry meat, 15.4% (95% CI: 12.0-19.5%). Prevalence data on the preservation type revealed that chilled poultry meat might be more likely to experience cross-contamination than non-chilled poultry meat in China. The distribution map of Salmonella for raw poultry meat showed that a higher prevalence level was found in the Shaanxi, Henan, Sichuan, and Beijing regions. All subgroups possessed high amounts of heterogeneity (I2 > 75%). The scientific data regarding the differences in prevalence levels between meat category, preservation method, and geographical region sources might be useful to improve specific interventions to effectively control the incidence of Salmonella in poultry meat.

Absorption and Tissue Distribution of Siphonaxanthin from Green Algae.

Siphonaxanthin has been known to possess inhibitory effects against obesity, inflammation, and angiogenesis. However, little information on its in vivo bioavailability and biotransformation is available. To assess the bioavailability and metabolism of siphonaxanthin, its absorption and accumulation were evaluated using intestinal Caco-2 cells and Institute of Cancer Research (ICR) mice. Siphonaxanthin was absorbed and exhibited non-uniform accumulation and distribution patterns in tissues of ICR mice. Notably, in addition to siphonaxanthin, three main compounds were detected following dietary administration of siphonaxanthin. Because the compounds showed changes on mass spectra compared with that of siphonaxanthin, they were presumed to be metabolites of siphonaxanthin in ICR mice. Siphonaxanthin mainly accumulated in stomach and small intestine, while putative metabolites of siphonaxanthin mainly accumulated in liver and adipose tissues. Furthermore, siphonaxanthin and its putative metabolites selectively accumulated in white adipose tissue (WAT), especially mesenteric WAT. These results provide useful evidence regarding the in vivo bioactivity of siphonaxanthin. In particular, the results regarding the specific accumulation of siphonaxanthin and its metabolites in WAT have important implications for understanding their anti-obesity effects and regulatory roles in lipid metabolism.

A Novel Human Placental Barrier Model Based on Trophoblast Stem Cells Derived from Human Induced Pluripotent Stem Cells.

The placenta acts as an interface between the fetus and the expecting mother. Various drugs and environmental pollutants can pass through the human placental barrier and may harm the developing fetus. Currently available in vitro placental barrier models are often inadequate, because they are lacking the functional trophoblast cells. Therefore, we developed and characterized a new human placental model using trophoblast stem cells (TSCs) derived from human induced pluripotent stem cells. Umbilical vein endothelial cells, fibroblast, and TSCs were cocultured using micromesh cell culture technique. These cells formed a tight three-layered structure. This coculture model induced progressive fusion of TSCs and formed a syncytialized epithelium that resembles the in vivo syncytiotrophoblast. Our model allowed the cultured trophoblasts to form microvilli and to reconstitute expression and physiological localization of membrane transport proteins, such as transporter for ATP-binding cassette subfamily B member 1, ATP-binding cassette subfamily C member 3, and glucose transporter-1. Drug permeability assays were performed using five compounds. The results from the permeability assays were comparable to the ones obtained with ex vivo placental models. In conclusion, we developed a novel coculture model mimicking human placenta that provides a useful tool for the studies on transfer of substances between the mother and fetus. Impact statement Compared with the currently available in vitro placental barrier models, a novel three-dimensional coculture placental barrier model presented in this study morphologically and functionally modeled the true placental barrier. The use of human trophoblast stem cells from human induced pluripotent stem cells substantially improved the current model. The use of micromesh sheet as a bioscaffold facilitated the formation of a good multilayer structure, which is closer to the physical appearance of the placenta observed in human.