Arabinogalactan Alleviates Lipopolysaccharide-Induced Intestinal Epithelial Barrier Damage through Adenosine Monophosphate-Activated Protein Kinase/Silent Information Regulator 1/Nuclear Factor Kappa-B Signaling Pathways in Caco-2 Cells.

Intestinal epithelial barrier (IEB) damage is an important aspect in inflammatory bowel disease (IBD). The objective of this study was to explore the protective effects and mechanisms of arabinogalactan (AG) on lipopolysaccharide (LPS)-stimulated IEB dysfunction. The results show that AG (1, 2, and 5 mg/mL) mitigated 100 µg/mL LPS-stimulated IEB dysfunction through increasing transepithelial electrical resistance (TEER), reducing fluorescein isothiocyanate (FITC)-dextran (4 kDa) flux, and up-regulating the protein and mRNA expression of tight junction (TJ) proteins (Claudin-1, Zonula occludens-1 (ZO-1) and Occludin). In addition, AG ameliorated LPS-stimulated IEB dysfunction by reducing interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1ß levels, decreasing the reactive oxygen species (ROS) level, increasing superoxide dismutase (SOD) activity, increasing the glutathione (GSH) level, and decreasing the levels of malondialdehyde (MDA) and intracellular calcium ([Ca2+]i). Furthermore, 2 mg/mL AG up-regulated the expression of silent information regulator 1 (SIRT1), the phosphorylated adenosine monophosphate-activated protein kinase (AMPK), and peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and inhibited the phosphorylation of nuclear factor kappa-B (NF-κB) and the inhibitor of NF-κBα (IκBα). Therefore, AG could maintain IEB integrity by activating AMPK/SIRT1 and inhibiting the NF-κB signaling pathway. In conclusion, AG can regulate the AMPK/SIRT1/NF-κB signaling pathway to reduce inflammation and oxidative stress, thus alleviating LPS-stimulated IEB damage.

Beetroot (Beta vulgaris) Extract against Salmonella Typhimurium via Apoptosis-Like Death and Its Potential for Application in Cooked Pork.

Salmonella Typhimurium is a common foodborne pathogen in meat and meat products, causing significant harm and losses to producers and consumers. The aim of this study was to investigate the antibacterial activity and possible mechanisms of beetroot (Beta vulgaris) extract against S. Typhimurium, as well as the application potential in cooked pork. The results suggested beetroot extract could inhibit S. Typhimurium with a minimum inhibitory concentration (MIC) of 20 mg/mL. After treatment with beetroot extract (1 or 2 MIC), S. Typhimurium exhibited the characteristics of apoptotic-like death (ALD), such as membrane depolarization, phosphatidylserine (PS) externalization, caspase-like protein activation, and DNA fragmentation. Further research has shown that the ALD induced by beetroot extract in S. Typhimurium was caused by reactive oxygen species (ROS) consumption, which was different from most natural products. The treatment of cooked pork with beetroot extract could reduce the number of S. Typhimurium, lower pH, defer lipid oxidation, and improve the colour. These results indicate that beetroot extract can inhibit S. Typhimurium through the ALD mechanism and has potential as an antibacterial agent against S. Typhimurium in ready-to-eat meat products.

Arabinogalactan ameliorates benzo[a]pyrene-induced intestinal epithelial barrier dysfunction via AhR/MAPK signaling pathway.

Benzo[a]pyrene (B[a]P), a kind of pollutant, can disrupt the gut microbiota, but its effects on the function of intestinal epithelial barrier (IEB) is still unclear. Arabinogalactan (AG), a natural polysaccharide, can protect intestinal tract. Thus, the purpose of this study was to evaluate the effect of B[a]P on IEB function and the mitigation effect of AG on the IEB dysfunction induced by B[a]P using a Caco-2 cell monolayer model. We found B[a]P could damage the IEB integrity by inducing cell cytotoxicity, increasing lactate dehydrogenase leakage, decreasing the transepithelial electrical resistance, and increasing fluorescein isothiocyanate-dextran flux. The mechanism of B[a]P-induced IEB damage may through induction of oxidative stress, including increasing reactive oxygen species levels, decreasing glutathione levels, reducing the activity of superoxide dismutase, and increasing malonaldehyde levels. Moreover, it can be due to increasing secretion of pro-inflammatory cytokines (interleukin [IL]-1ß, IL-6, and tumor necrosis factor [TNF]-α), down-regulated expression of tight junction (TJ) proteins (claudin-1, zonula occludens [ZO]-1, and occludin), and induced activation of aryl hydrocarbon receptor (AhR)/mitogen activated protein kinase (MAPK) signaling pathway. Remarkably, AG ameliorated B[a]P-induced IEB dysfunction through inhibited oxidative stress and pro-inflammatory factor secretion. Our study demonstrated B[a]P could damage the IEB and AG could alleviate this damage.

Depletion of reactive oxygen species induced by beetroot (Beta vulgaris) extract leads to apoptosis-like death in Cronobacter sakazakii.

This research aimed to disclose the antibacterial activity of beetroot extract (Beta vulgaris) against Cronobacter sakazakii and its possible mechanisms. We evaluated its antibacterial activity by measuring the minimum inhibitory concentration (MIC) and time-kill kinetics. We also evaluated the intracellular ATP levels, bacterial apoptosis-like death (ALD), and reactive oxygen species (ROS) levels to reveal the possible antibacterial mechanisms. Our results showed that the MIC of beetroot extract against C. sakazakii was 25 mg/mL and C. sakazakii (approximately 8 log cfu/mL) was completely inhibited after treatment with 2 MIC of beetroot extract for 3 h. Beetroot extract reduced intracellular ATP levels and facilitated characteristics of ALD in C. sakazakii, such as membrane depolarization, increased intracellular Ca2+ levels, phosphatidylserine externalization, caspase-like protein activation, and DNA fragmentation. Additionally, and different from most bacterial ALD caused by the accumulation of ROS, beetroot extract reduced the intracellular ROS levels in C. sakazakii. Our experimental data provide a rationale for further research of bacterial ALD and demonstrate that beetroot extract can inhibit C. sakazakii in food processing environments.

The Impact of Emotional Feedback and Elaborated Feedback of a Pedagogical Agent on Multimedia Learning.

This study aimed to explore the impact of emotional feedback and elaborated feedback provided by a pedagogical agent (PA) on learners' emotions, intrinsic motivation, agent perception, cognitive load, and transfer performance in multimedia learning. The experiment was conducted based on an actual undergraduate course. Undergraduate students (N = 117) were randomly assigned to one of the four conditions, where PA's feedback differed by emotional feedback (with vs. without) and elaborated feedback (elaborated feedback vs. knowledge of results). Results revealed that emotional feedback reduced learners' confusion, activated intrinsic motivation, and enhanced agent perception. In addition, elaborated feedback improved intrinsic motivation, agent perception, and transfer performance but reduced germane cognitive load. Surprisingly, there was no significant interaction between emotional feedback and elaborated feedback. These findings had implications for designing a PA with a feedback fulfilling learners' emotional and cognitive needs to maximize multimedia learning.

Taxifolin ameliorates lipopolysaccharide-induced intestinal epithelial barrier dysfunction via attenuating NF-kappa B/MLCK pathway in a Caco-2 cell monolayer model.

Intestinal epithelial barrier dysfunction can cause several intestinal diseases. Flavonoids have been shown to be beneficial to the intestinal epithelial barrier function. However, the effects of taxifolin (TAX), a naturally occurring flavonoid, on the intestinal epithelial barrier function are unclear. Thus, the aims of this study were to investigate the protective effect and potential mechanism of TAX against lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction in a Caco-2 cell monolayer model. Our results showed that TAX increased the transepithelial electrical resistance (TEER) and decreased the fluorescein isothiocyanate (FITC)-dextran (4 kDa) flux in the damaged intestinal epithelial barrier. Meanwhile, TAX inhibited an LPS-induced decrease in mRNA and protein expression of tight junction (TJ) proteins (claudin-1, zonula occludens [ZO]-1, and occludin), and ameliorating the continuous distribution pattern disrupted of TJs. These results suggested that TAX ameliorated intestinal epithelial barrier dysfunction. Regarding the underlying mechanism, TAX reduced the LPS-induced secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 in Caco-2 cell monolayers. In addition, TAX suppressed the phosphorylation of nuclear factor kappa-B (NF-κB), inhibitor protein of NF-κBα (IκBα), and myosin light chain (MLC), and downregulated the expression of myosin light chain kinase (MLCK) in LPS-treated Caco-2 cells. In summary, TAX can maintain TJ proteins by inhibiting the NF-κB/MLCK pathway and pro-inflammatory factor secretion to ameliorate LPS-induced intestinal epithelial barrier dysfunction. Thus, TAX is a promising candidate agent for use in functional food to ameliorate intestinal barrier dysfunction.

The Relationship between Empathy and Attachment in Children and Adolescents: Three-Level Meta-Analyses.

Empathy is one of the leading social abilities to understand or feel the emotions of other people. Attachment is thought to be a critical influential factor of empathy, as revealed by attachment theory and experimental studies, while empathy is also believed to facilitate the quality of attachment. Although many studies are conducted concerning the two subjects, the direction and magnitude of their relationship still remain unclear. In order to clarify the discrepant results in the previous study and explore the moderators in the empathy-attachment association, three-level meta-analyses were conducted in the present work. Based on 212 effect sizes from 59 samples in 50 studies with a total of 24,572 participants, random effect model analyses showed that empathy was insignificantly correlated with anxious attachment, significantly negatively correlated with avoidant attachment, and significantly positively correlated with secure attachment. The meta-analytic results indicated that children and adolescents with high secure attachment tend to show more empathy than those with low secure attachment. The meta-regression model revealed significant effects of the empathy dimension, culture, empathy measurement tools, and publication state. Additionally, implications and future directions for the empathy-attachment relationship were also discussed.

Structural and Emulsifying Properties of Soybean Protein Isolate-Sodium Alginate Conjugates under High Hydrostatic Pressure.

Soybean protein isolate (SPI) is a kind of plant derived protein with high nutritional value, but it is underutilized due to its structural limitations and poor functionalities. This study aimed to investigate the effects of high hydrostatic pressure (HHP) treatment on SPI and sodium alginate (SA) conjugates prepared through the Maillard reaction. The physicochemical properties of the conjugate synthesized under 200 MPa at 60 °C for 24 h (SPI-SA-200) were compared with those of the conjugate synthesized under atmospheric pressure (SPI-SA-0.1), SPI-SA mixture, and SPI. The HHP (200 MPa) significantly hindered the Maillard reaction. This effect was confirmed by performing SDS-PAGE. The alterations in the secondary structures, such as α-helices, were analyzed using circular dichroism spectroscopy and the fluorescence intensity was determined. Emulsifying activity and stability indices of SPI-SA-200 increased by 33.56% and 31.96% respectively in comparison with the SPI-SA-0.1 conjugate. Furthermore, reduced particle sizes (356.18 nm), enhanced zeta potential (‒40.95 mV), and homogeneous droplet sizes were observed for the SPI-SA-200 emulsion. The present study details a practical method to prepare desirable emulsifiers for food processing by controlling the Maillard reaction and improving the functionality of SPI.

The Effects of Emotional Design on Multimedia Learning and Appreciation of Chinese Poetry.

Painting, music, literature, and other art forms embody the essence of human wisdom and induce esthetic experience, among which poetry is inherently creative, because it contains a wealth of symbols, imageries, insights, and so forth. The appreciation and learning of Chinese poetry is an important part of the curriculum in secondary schools. However, studies have mainly focused on textual characters of poetry, with little literature focusing on esthetic appreciation and in-depth learning of poetry. In this vein, we ask whether emotional designs will promote the appreciation and learning of Chinese poetry. To answer this question, we explored the influence of the combination of external emotion induction (positive and neutral movie clips) and internal colorful design (chromatic and achromatic) on esthetic preference and learning of poetry. One hundred and sixty-six participants (14-15 years old) were randomly assigned to one of four conditions created by two factors (external emotion induction and internal colorful design). The results showed that the combination of external emotion induction and internal colorful design promoted positive emotions, retention, and transfer performances of learners. Furthermore, perceived difficulty of learners decreased significantly when external emotional induction and internal colorful design were both positive. Consequently, these findings indicated that emotional designs in multimedia facilitated the learning performance of middle school students in Chinese poetry, and supported the cognitive-affective theory of learning with media. This research was a preliminary exploration of emotional design in humanities.

Action mode of cranberry anthocyanin on physiological and morphological properties of Staphylococcus aureus and its application in cooked meat.

This study researched the action mode of cranberry anthocyanin (CA) against Staphylococcus aureus and the effect of CA on the counts of S. aureus and the quantity of cooked meat during storage. The antibacterial effect was assessed by minimum inhibitory concentration (MIC) and survival populations of S. aureus strains after CA treatments. The changes in intracellular adenosine 5'-triphosphate (ATP) concentration, cell membrane potential, content of bacterial protein and cell morphology were analyzed to reveal possible action mode. Application potentials of CA as antimicrobial agent were assessed during storage of cooked pork and beef. The result showed that the MIC of CA against S. aureus strains was 5 mg/mL. Approximately 8 log CFU/mL of S. aureus strains can be completely inhibited after treatment with 2.0 MIC of CA for 0.5 h. Treatments of CA resulted in lower intracellular ATP and soluble protein levels, damaged membrane structure and leakage of cytoplasmic. Application of CA on cooked pork and beef caused a significant decrease in S. aureus counts and pH values, and color-darkening compared with control samples. These findings demonstrated that CA played an effective antimicrobial against S. aureus and had a potential as natural preservative to inhibit the growth of food pathogens.

Benefits of Affective Pedagogical Agents in Multimedia Instruction.

The goal of the present study is to explore whether the affective states (happy or neutral) of a pedagogical agent (PA) in an online multimedia lesson yields different learning processes and outcomes, and whether the effects of affective PAs depend on the learners' emotion regulation strategies and their prior knowledge. In three experiments, undergraduates were asked to view a narrated animation about synaptic transmission that included either a happy PA (smiling expression and enthusiastic voice) or a neutral PA (neutral expression and calm voice) and subsequently took emotions, motivation, cognitive outcomes tests. Across three experiments, the happy PA group reported more positive emotions (ds = 0.70, 0.46, and 0.60) and higher level of motivation (ds = 0.76, 0.49, and 0.51) than the neutral PA group. Moreover, the happy PA prompted higher germane load (d = 0.41) than a neutral PA in Experiment 3. However, adding a happy PA to the screen did not improve learning performance. In addition, in Experiment 2, learners' usage of emotion regulation strategies moderated the effectiveness of affective PA on positive emotions in learners. Specifically, happy PAs increased the positive emotions of students who used expressive suppression strategy (d = 0.99) but not those who used cognitive reappraisal strategy (d = 0.13). In Experiment 3, the effectiveness of affective PAs was not moderated by learners' prior knowledge. Results support the cognitive affective theory of learning with media (CATLM) that students are happier and more motivated when they learn from happy PAs than from neutral PAs.

Antibacterial Activity of Olive Oil Polyphenol Extract Against Salmonella Typhimurium and Staphylococcus aureus: Possible Mechanisms.

Polyphenols are a group of active ingredients in olive oil, and have been reported to exhibit antioxidant activity. Salmonella enterica subsp. enterica serovar Typhimurium (Salmonella Typhimurium) and Staphylococcus aureus are common foodborne pathogens causing serious infections and food poisoning in humans. This study was conducted to analyze the antibacterial activity of olive oil polyphenol extract (OOPE) against Salmonella Typhimurium and S. aureus, and reveal the possible antibacterial mechanism. The antibacterial activity was estimated using minimum inhibitory concentration (MIC) values and bacterial survival rates when treated with OOPE. The antibacterial mechanism was revealed through determinations of changes in intracellular ATP concentration and cell membrane potential, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and transmission electron microscopy analysis. The results showed the MICs of OOPE against Salmonella Typhimurium and S. aureus were 0.625 and 0.625-1.25 mg/mL, respectively. The growth of Salmonella Typhimurium and S. aureus (∼8 log CFU/mL) was completely inhibited after treatments with 0.625 mg/mL of OOPE for 3 h and 0.625-1.25 mg/mL for 5 h, respectively. When Salmonella Typhimurium and S. aureus were exposed to OOPE, the physiological functions associated with cell activity were destroyed, as manifested by reduction of intracellular ATP concentrations, cell membrane depolarization, lower bacterial protein content, and leakage of cytoplasm. These findings suggested a strong antibacterial effect of OOPE against Salmonella Typhimurium and S. aureus, and provided a possible strategy of controlling contamination by these two pathogens in food products.

Effect of milk types on the attributes of a glutinous rice wine-fermented yogurt-like product.

This study was conducted to analyze the effect of milk types on the attributes of the glutinous rice wine-fermented yogurt-like product named Kouwan Lao (KWL). Four types of raw milks were used in this study, including high temperature, long time (HTLT: H milk), HTLT milk supplemented with 3% skim milk powder (S milk), pasteurized milk (P milk), and ultra-high temperature milk (U milk). Microbiological compositions of the fermented glutinous rice and KWL at different stages were analyzed using PCR-denaturing gradient gel electrophoresis and gene sequencing based on 16S rRNA and 26S rRNA. The physicochemical properties of KWL samples were determined, and textural properties of those were analyzed using a texture analyzer (Jiawei Innovation and Technology Co. Ltd., Zhejiang Province, China). The microstructure of KWL samples was observed using scanning electron microscopy. The results showed that the milk types had significant influences on the bacterial composition of KWL. In the curdling process, the predominant bacteria of H, S, P, and U KWL samples were Lactobacillus brevis, Janthinobacterium sp., Lactobacillus casei, and Streptococcus agalactiae, respectively. In the ripening process, the main strains in H KWL were Enterococcus faecium and Pediococcus pentosaceus. Lactobacillus casei and Lactobacillus paracasei were the dominant bacteria of U KWL. Lactobacillus casei was the main strain of P KWL, and no bacteria were detected in S KWL. Saccharomyces cerevisiae was the dominant fungus of KWL, and no significant effect of milk types on fungal composition of KWL was found. The results of physicochemical properties showed that significant differences in protein contents were found in the KWL samples, and P KWL had the highest protein content. The fat content of U KWL was significantly higher than that of samples from the other 3 groups. The U KWL and P KWL showed lower moisture than that of the other 2 KWL samples. In addition, no significant difference in pH value was found in all samples. The results of texture analysis and microstructure showed that compared with other 3 types of KWL samples, the related mass parameters of U KWL were more advantageous and improved significantly with the increase of the heat treatment temperature of raw milk and the addition of skim milk powder. Our findings revealed the effects of milk types on microbial composition, physicochemical properties, textural properties, and microstructure of KWL, and provided a basic theory for the optimization and industrial production of KWL.

Antimicrobial Activity and Action Approach of the Olive Oil Polyphenol Extract Against Listeria monocytogenes.

Olive oil polyphenol extract (OOPE) has been reported to have antibacterial activity; however, its effect on Listeria monocytogenes is less studied so far. This study, thus, aimed to reveal its antimicrobial activity and action approach against L. monocytogenes via evaluating the minimum inhibitory concentration (MIC) as well as the changes of intracellular adenosine 5'-triphosphate (ATP) concentration, cell membrane potential, bacterial protein, DNA, and cell morphology. The results showed that OOPE could inhibit the growth of L. monocytogenes with a measured MIC of 1.25 mg/ml. L. monocytogenes cells treated by OOPE showed significant reduction in intracellular ATP concentrations, bacterial protein, or DNA (p < 0.05), in comparison with those without any treatment. In addition, OOPE was observed to depolarize strain cells and alter cell morphology, resulting in damaged cell membrane and, thereby, leakage of cell fluid. These findings demonstrated that OOPE had inhibition on L. monocytogenes via its action on cells, suggesting its potential as a natural preservative.

Effects of Parental Autonomy Support and Teacher Support on Middle School Students' Homework Effort: Homework Autonomous Motivation as Mediator.

The present study tested whether students' autonomous motivation mediated the association between adult support (parental autonomy support, teacher support) and students' homework effort. A sample of 666 Chinese middle school students was recruited to complete the parental autonomy support questionnaire, teacher support questionnaire, homework autonomous motivation questionnaire and homework effort questionnaire. Structural equation modeling showed that both parental autonomy support and teacher support positively predicted mathematics homework effort, and mathematics homework autonomous motivation was a mediator in these associations. The present study reveals the importance of adult support and autonomous motivation, and has theoretical and practical implications.

Olive oil polyphenol extract inhibits vegetative cells of Bacillus cereus isolated from raw milk.

This study was conducted to analyze the antibacterial effect of olive oil polyphenol extract (OOPE) against vegetative cells of Bacillus cereus isolated from raw milk and reveal the possible antibacterial mechanism. The diameter of inhibition zone, minimum inhibitory concentration, minimum bactericidal concentration, and survival counts of bacterial cells in sterile normal saline and pasteurized milk were used to evaluate the antibacterial activity of OOPE against B. cereus vegetative cells. The changes in intracellular ATP concentration, cell membrane potential, content of bacterial protein, and cell morphology were analyzed to reveal possible mechanisms of action. Our results showed the diameter of inhibition zone, minimum inhibitory concentration, and minimum bactericidal concentration of OOPE against B. cereus vegetative cells were 18.44 ± 0.55 mm, 0.625 mg/mL, and 1.25 mg/mL, respectively. Bacillus cereus GF-1 vegetative cells were decreased to undetectable levels from about 8 log cfu/mL after treatments with 0.625 mg/mL of OOPE in normal saline at 30°C for 3 h and in pasteurized milk at 30°C for 10 h. The antibacterial mechanisms of OOPE against B. cereus GF-1 vegetative cells may be due to the reduction of intracellular ATP concentrations, cell membrane depolarization, decrease of bacterial protein content, and leakage from cytoplasm. These findings illustrated that OOPE could be used to prevent the growth of contaminating B. cereus cells in dairy products.

More Attractive or More Interactive? The Effects of Multi-Leveled Emotional Design on Middle School Students' Multimedia Learning.

Previous studies on multimedia learning have provided shreds of evidence for the positive effect of visually attractive emotional design on college students' emotion and learning outcomes. However, the effect may vary among middle school students. The aim of this study was to examine the impacts of visual and behavioral emotional design on the emotional, motivational and cognitive outcomes of middle school students. In Experiment 1, 50 participants (ages 13-15) were randomly assigned to one of two conditions: visual positive emotional design (colorful and anthropomorphic design) and visual neutral emotional design (achromatic and without anthropomorphic design). In Experiment 2, 173 participants (ages 13-16) were randomly assigned to one of four conditions created by the two factors: visual emotional design (positive vs. neutral) and behavioral emotional design (positive vs. neutral). The behavioral positive emotional design allows learners to interact with learning materials, whereas behavioral neutral emotional design only allows learners to watch learning video. Results showed that both visually attractive and behaviorally interactive design (visual positive emotion design and behavioral positive emotional design) had positive effect on learners' positive emotions. Combining visual positive with behavioral positive emotional design could facilitate learning performance.

Occurrence, Genotyping, and Antibiotic Susceptibility of Cronobacter spp. in Drinking Water and Food Samples from Northeast China.

Cronobacter species (formerly Enterobacter sakazakii) are emerging opportunistic bacterial pathogens that can infect both infants and adults. This study was conducted to isolate and genotype diverse Cronobacter species from drinking water, chilled fresh pork, powdered infant formula, instant noodles, cookies, fruits, vegetables, and dishes in Northeast China and to evaluate the antibiotic resistance and susceptibility of the isolates. Thirty-four Cronobacter strains were isolated and identified: 21 C. sakazakii isolates (61.8%), 10 C. malonaticus isolates (29.4%), 2 C. dublinensis isolates (5.9%), and 1 C. turicensis isolate (2.9%). These isolates were further divided into 15 sequence types (STs) by multilocus sequence typing. C. sakazakii ST4 (10 isolates, 29.4%), ST1 (3 isolates, 8.8%), and ST8 (3 isolates, 8.8%) and C. malonaticus ST7 (four isolates, 11.8%) were dominant. Antibiotic susceptibility testing indicated that all 34 Cronobacter isolates were susceptible to ampicillin-sulbactam, cefotaxime, ciprofloxacin, gentamicin, meropenem, tetracycline, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole, 88.2% were susceptible to chloramphenicol, and 67.6% were resistant to cephalothin. The results of this study enhance knowledge about genotyping and antibiotic resistance of these Cronobacter species and could be used to prevent potential hazards caused by these strains in drinking water and various food products.