Identification and Characterization of a Bacteriocin from the Newly Isolated Bacillus subtilis HD15 with Inhibitory Effects against Bacillus cereus.

Natural antimicrobial substances are needed as alternatives to synthetic antimicrobials to protect against foodborne pathogens. In this study, a bacteriocin-producing bacterium, Bacillus subtilis HD15, was isolated from doenjang, a traditional Korean fermented soybean paste. We sequenced the complete genome of B. subtilis HD15. This genome size was 4,173,431 bp with a G + C content of of 43.58%, 4,305 genes, and 4,222 protein-coding genes with predicted functions, including a subtilosin A gene cluster. The bacteriocin was purified by ammonium sulfate precipitation, Diethylaminoethanol-Sepharose chromatography, and Sephacryl gel filtration, with 12.4-fold purification and 26.2% yield, respectively. The purified protein had a molecular weight of 3.6 kDa. The N-terminal amino acid sequence showed the highest similarity to Bacillus subtilis 168 subtilosin A (78%) but only 68% similarity to B. tequilensis subtilosin proteins, indicating that the antimicrobial substance isolated from B. subtilis HD15 is a novel bacteriocin related to subtilosin A. The purified protein from B. subtilis HD15 exhibited high antimicrobial activity against Listeria monocytogenes and Bacillus cereus. It showed stable activity in the range 0-70°C and pH 2-10 and was completely inhibited by protease, proteinase K, and pronase E treatment, suggesting that it is a proteinaceous substance. These findings support the potential industrial applications of the novel bacteriocin purified from B. subtilis HD15.

Dynamic Changes in Fecal Microbial Communities of Neonatal Dairy Calves by Aging and Diarrhea.

Microbiota plays a critical role in the overall growth performance and health status of dairy cows, especially during their early life. Several studies have reported that fecal microbiome of neonatal calves is shifted by various factors such as diarrhea, antibiotic treatment, or environmental changes. Despite the importance of gut microbiome, a lack of knowledge regarding the composition and functions of microbiota impedes the development of new strategies for improving growth performance and disease resistance during the neonatal calf period. In this study, we utilized next-generation sequencing to monitor the time-dependent dynamics of the gut microbiota of dairy calves before weaning (1-8 weeks of age) and further investigated the microbiome changes caused by diarrhea. Metagenomic analysis revealed that continuous changes, including increasing gut microbiome diversity, occurred from 1 to 5 weeks of age. However, the composition and diversity of the fecal microbiome did not change after 6 weeks of age. The most prominent changes in the fecal microbiome composition caused by aging at family level were a decreased abundance of Bacteroidaceae and Enterobacteriaceae and an increased abundance of Prevotellaceae. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis indicated that the abundance of microbial genes associated with various metabolic pathways changed with aging. All calves with diarrhea symptoms showed drastic microbiome changes and about a week later returned to the microbiome of pre-diarrheal stage regardless of age. At phylum level, abundance of Bacteroidetes was decreased (p = 0.09) and that of Proteobacteria increased (p = 0.07) during diarrhea. PICRUSt analysis indicated that microbial metabolism-related genes, such as starch and sucrose metabolism, sphingolipid metabolism, alanine aspartate, and glutamate metabolism were significantly altered in diarrheal calves. Together, these results highlight the important implications of gut microbiota in gut metabolism and health status of neonatal dairy calves.

Differential Dynamics of the Ruminal Microbiome of Jersey Cows in a Heat Stress Environment.

The microbial community within the rumen can be changed and shaped by heat stress. Accumulating data have suggested that different breeds of dairy cows have differential heat stress resistance; however, the underlying mechanism by which nonanimal factors contribute to heat stress are yet to be understood. This study is designed to determine changes in the rumen microbiome of Holstein and Jersey cows to normal and heat stress conditions. Under heat stress conditions, Holstein cows had a significantly higher respiration rate than Jersey cows. Heat stress increased the rectal temperature of Holstein but not Jersey cows. In the Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis, Jersey cows had a significantly higher proportion of genes associated with energy metabolism in the normal condition than that with other treatments. Linear discriminant analysis effect size (LEfSe) results identified six taxa as distinguishing taxa between normal and heat stress conditions in Holstein cows; in Jersey cows, 29 such taxa were identified. Changes in the rumen bacterial taxa were more sensitive to heat stress in Jersey cows than in Holstein cows, suggesting that the rumen mechanism is different in both breeds in adapting to heat stress. Collectively, distinct changes in rumen bacterial taxa and functional gene abundance in Jersey cows may be associated with better adaptation ability to heat stress.

A functional regulatory variant of MYH3 influences muscle fiber-type composition and intramuscular fat content in pigs.

Muscle development and lipid accumulation in muscle critically affect meat quality of livestock. However, the genetic factors underlying myofiber-type specification and intramuscular fat (IMF) accumulation remain to be elucidated. Using two independent intercrosses between Western commercial breeds and Korean native pigs (KNPs) and a joint linkage-linkage disequilibrium analysis, we identified a 488.1-kb region on porcine chromosome 12 that affects both reddish meat color (a*) and IMF. In this critical region, only the MYH3 gene, encoding myosin heavy chain 3, was found to be preferentially overexpressed in the skeletal muscle of KNPs. Subsequently, MYH3-transgenic mice demonstrated that this gene controls both myofiber-type specification and adipogenesis in skeletal muscle. We discovered a structural variant in the promotor/regulatory region of MYH3 for which Q allele carriers exhibited significantly higher values of a* and IMF than q allele carriers. Furthermore, chromatin immunoprecipitation and cotransfection assays showed that the structural variant in the 5'-flanking region of MYH3 abrogated the binding of the myogenic regulatory factors (MYF5, MYOD, MYOG, and MRF4). The allele distribution of MYH3 among pig populations worldwide indicated that the MYH3 Q allele is of Asian origin and likely predates domestication. In conclusion, we identified a functional regulatory sequence variant in porcine MYH3 that provides novel insights into the genetic basis of the regulation of myofiber type ratios and associated changes in IMF in pigs. The MYH3 variant can play an important role in improving pork quality in current breeding programs.

The fates of microbial populations on pig carcasses during slaughtering process, on retail cuts after slaughter, and intervention efficiency of lactic acid spraying.

This study was conducted to detect and identify microbial populations on pig carcasses at different slaughtering stages and on retail pork cuts at 24 h after slaughter as well as to evaluate the intervention efficiency of sprays containing different concentrations (2% and 4%) of lactic acid. The sprays were applied to the carcass surfaces at the end of the slaughter line. Microbial samples were collected from carcass surfaces after bleeding and after eviscerating, and from retail cuts at 24 h after chilling/spraying. The detected microorganisms were identified through using a Microflex identification instrument and 16S rRNA gene sequencing. The diversity of the bacterial genera; Staphylococcus, Salmonella, Shigella, Enterococci, Escherichia, Acinetobacter and Corynebacterium spp. showed counts ranging from 2.70 to 4.91 log10 cfu/100 cm2 on the carcasses during slaughter. Most of these genera were also detected on the carcasses after 24 h of chilling. Three species (Staphylococcus hyicus, Acinetobacter albensis, and Corynebacterium xerosis) were also found on the retail cuts of non-sprayed carcasses but not on those of the sprayed groups. Significantly greater reductions in all bacterial species were observed on the carcasses and retail cuts that were sprayed with lactic acid, particularly at the 4% level. Thus, spraying with 4% lactic acid may be an effective intervention for controlling bacterial contamination on pig carcasses to improve the microbiological safety of pork meat.

Characterisation of the bacterial community in the gastrointestinal tracts of elk (Cervus canadensis).

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.

Comparative study of nutritional composition and color traits of meats obtained from the horses and Korean native black pigs raised in Jeju Island.

OBJECTIVE: The present study aimed at comparing the nutritional composition and color traits between two meat types: Horse meat and pork from Korean native black pigs raised in Jeju Island. METHODS: After slaughter 24 h, the longissimus dorsi samples were taken from left side carcasses of the 32-mo-old Jeju female breed horses and the 6-mo-old Korean native black pigs (n = 10 each). The samples were then placed into cool boxes containing ice packs and transported to the Laboratory of Meat Science where all visual fats and connective tissues were trimmed off and then the samples were ground. All the samples were analyzed for nutritional composition (proximate composition, minerals, vitamins, fatty acids, and amino acids) and color traits. RESULTS: The horse meat contained significantly higher collagen, moisture and protein than the pork (p<0.05). The Jeju horse meat showed more desirable fatty acid profiles such as containing significantly lower saturated fatty acids (SFA), higher polyunsaturated fatty acids (PUFA) contents and PUFA/SFA ratios than the pork (p<0.05). Differences in concentrations of ten amino acids existed between the two meat types in which the horse meat had higher values for all these amino acids, total amino acids (20.33 g/100 g) and essential amino acids (10.06 g/100 g) than the pork (p<0.05). Also, the horse meat showed significantly higher concentrations of Fe (34.21 mg/100 g) and Cu (2.47 mg/100 g) than the pork (Fe, 17.42 mg/100 g and Cu, 1.51 mg/100 g) (p<0.05). All the vitamins detected showed statistical differences between the two meat types in which the horse meat had higher concentrations of vitamin B1 (25.19 mg/100 g), B2 (92.32 mg/100 g), B3 (2,115.51 mg/100 g), and B5 (67.13 mg/100 g) than the pork (p<0.05). CONCLUSION: Based on the results obtained in the study, it is concluded that the two meat types studied are rich in nutrients and the animal species strongly affected the nutritional values and color traits of the muscle tissues.

Lactobacillus plantarum (KACC 92189) as a Potential Probiotic Starter Culture for Quality Improvement of Fermented Sausages.

This study was conducted to evaluate the effects of fermenting temperature on the applicability of Lactobacillusplantarum for production of fermented sausages as starter cultures, and its applicable efficiency was also compared with those inoculated with commercial starter culture or non-inoculated control. The L. plantarum isolated from a naturally-fermented meat, identified by 16S rDNA sequencing and again identified by denovo Assembly Analysis method was used as a starter culture. Six treatments: 3 with L. plantarum at different fermenting temperatures (20, 25 and 30°C), and other 3 treatments (1 with commercial starter culture, 1 with its mixture with L. plantarum and 1 non-inoculated control) fermented under the same conditions (25°C) were prepared. Results revealed that the fermenting temperature considerably affected the pH change in samples added with L. plantarum; the highest pH drop rate (1.57 unit) was obtained on the samples fermented at 30°C, followed by those at 25°C (1.3 unit) and 20°C (0.99 unit) after 4 days fermentation. Increasing the temperature up to 30°C resulted in significantly lower spoilage bacteria count (5.15 log CFU/g) and lipid oxidation level in the products inoculated with L. plantarum. The sensory analysis also showed that the samples added with L. plantarum at 30°C had significantly higher odor, taste and acceptability scores than those fermented at lower temperatures. Under the same processing condition, although the L. plantarum showed slightly lower acidification than the commercial starter culture, however, it significantly improved the eating quality of the product.

Changes in Total Plate Counts and Quality of Pig Small Intestine by Different Washing and Packaging Methods.

Pig small intestine not only is used as food but also for sausage casings production in many countries worldwide. However, it is well recognized that the small intestine is important source of spoilage and pathogenic bacteria. The present study aimed at investigating the effects of different washing and packaging methods on the changes of microbial levels and physicochemical characteristics of pig small intestine. After collecting and trimming off of visible fats, the pig small intestine samples were treated with; (i) different packaging methods: aerobic packaging (AP), skin packaging (SP), and vacuum packaging (VP); and (ii) washing with different concentrations of acetic acid. The treated samples were then stored at 4℃ for 1, 4, 7, and 10 d. At 1-d storage, higher pH value was found in the AP-treated samples, however, after 7 to 10 days the samples treated with SP had higher values compared to the ones treated with AP and VP (p<0.05). Thiobarbituric acid reactive substances values were higher in the AP-treated samples than those of the SP- and VP- treated samples at 7-d storage (p<0.05). At 10th d, total plate counts (TPC) were higher in the control than in the acetic acid-washed samples (p<0.05). Additionally, the TPC was lower in the SP- and VP-treated samples than the AP-treated samples at 7-d storage (p<0.05). These obtained results suggest that the applications of washing with acetic acid solution and/or SP and VP methods could be an effective way to extend the shelf-life of pig small intestine during cold distribution.

Effect of Aging and Freezing Conditions on Meat Quality and Storage Stability of 1++ Grade Hanwoo Steer Beef: Implications for Shelf Life.

This study was conducted to establish the shelf life of 1++ grade Hanwoo beef by evaluating the changes in meat quality and storage stability under distribution conditions similar to those during export to Hong Kong and China. Four muscles of the loin, striploin, tenderloin, and top round muscles were obtained from 10 animals of 1++ grade Hanwoo steers. The distribution conditions were 0, 7, or 14 d of aging at 2°C and continuous storage at -18°C for 0, 3, 6, or 9 mon. The lightness (CIE L*) values decreased as the duration of freezer storage increased (p<0.05). The water-holding capacity of 4 muscles increased as the aging time increased when they were frozen for 3 mon (p<0.05). The cooking loss values of the four muscles were significantly increased as the duration of freezer storage increased (p<0.05). The Warner-Bratzler shear force values were significantly decreased in the loin, striploin, and top round muscles as the aging time increased (p<0.05). The changes in volatile basic nitrogen (16.67-18.49 mg%) and thiobarbituric reactive substance values (0.75-0.82 mg MA/kg meat) were significantly increased when the meat was frozen for 9 mon after 14 d of aging. On the basis of these observations, the shelf life of 1++ grade Hanwoo beef during distribution should be limited to less than 9 mon of freezer storage at -18°C after 14 d of aging at 2°C.

Effects of Additions of Monascus and Laccaic acid on the Color and Quality Properties of Nitrite-Free Emulsion Sausage during Refrigerated Storage.

This effect of Monascus and Laccaic acid on the chemical composition, physical, texture and sensory properties of sausage were investigated during storage. Eight treatments (T) of sausage such as T1 (12 ppm sodium nitrite), while T2, T3, T4, T5, T6 and T7 were formulated with different ratios of Monascus/Laccaic acid: 63/7.0, 108/12, 135/15, 59.5/10.5, 102/18 and 127.5/22.5 ppm, respectively. The batch formulated without nitrite or Monascus and laccaic acid was served as control (C). The control sausages had higher pH values compared to the treated ones at 3, 10 and 28 d storage (p<0.05). After 10 d storage, the pH values decreased in treated sausage samples (p<0.05). The T1 and T4 presented the lowest yellowness and lightness values, respectively over the storage period. The redness values were increased as increasing Monascus and Laccaic acid amounts (T2-T4, T5-T7). The addition of Monascus and Laccaic acid had significantly higher hardness and springiness values (p<0.05) compared with the control in 3, 19 or 28 d storage. The results indicated that the addition of Monascus and Laccaic acid could improve the redness of the products.

Meat quality traits as a function of cow maturity.

To investigate the physico-chemical and sensory properties of striploin muscles, 90 Hanwoo carcasses (QG 1+ ) were randomly selected within six maturity levels (4 to 9 according to age in months). Results demonstrated that the protein contents at maturity levels 4 and 5 were significantly higher than 9. No significant difference in fat, moisture and collagen contents were found at different maturity levels (P > 0.05). The quantity of collagen type I and ratio of type I to III were observed at higher maturity levels; collagen type III showed significantly high levels (P > 0.05) at low maturity and decreased with increase in maturity levels. Warner-Bratzler shear force (WBSF) was significantly lower in groups 4 to 6, whereas water holding capacity (WHC) was significantly higher than maturity level 8 and 9 groups (P < 0.05). There were no significant differences in cooking loss among the maturity level groups (P > 0.05). Color properties, L* values of striploin muscle from maturity level 4 were significantly different from level 9 (P < 0.05). Sensory evaluation at level 4-6 groups had significantly higher tenderness and overall likeness scores than level 9 (P < 0.05). The maturity levels were significantly correlated with age, fat, protein content, WHC, WBSF, cooking loss, CIE L* values and sensory properties like tenderness, juiciness, flavor-likeness and overall likeness.

Effects of low NaNO2 and NaCl concentrations on Listeria monocytogenes growth in emulsion-type sausage.

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.

Cholesterol-lowering and lipid oxidation reduction potentials of traditional seasonings in Salchichon dry-fermented sausages.

Five different natural/traditional seasonings including doenjang (fermented soybean paste), gochu-jang (red pepper paste), fresh medium-hot and hot peppers, and garlic were used, and 1 % (w/w) each was incorporated into formulations of Salchichon fermented sausage type. After ripening for 51 days, the products were assessed for quality parameters, lipid oxidation, cholesterol content and sensory characteristics. In general, incorporation of the seasonings did not cause color or texture defects whereas it had beneficial effects on improvement of product's quality; however the effects differed depending on each type of seasonings added. Noticeably, most treatments with the seasonings significantly reduced the lipid oxidation. Additionally, incorporating doenjang, gochu-jang, medium-hot peppers, hot peppers and garlic resulted in reduction of 32.03, 28.96, 36.30, 19.53 and 33.03 mg cholesterol/100 g sample, corresponding to 26.78, 24.21, 30.35, 16.33 and 27.61 %, respectively. Higher scores for the sensory traits such as aroma, taste, color and acceptability were also observed for the samples with seasonings. The current work demonstrated that the tested seasonings represent potentially natural ingredients for producing healthier Salchichon fermented sausages.

Effect of Ultra-sonication Treatment on the Quality Characteristics of Baked Eggs.

The effect of ultra-sonication on quality characteristics and flavor of baked eggs was studied. One hundred and twenty eggs were cooked and assigned to six treatments groups (n=20 each) that were then soaked in saline solution at various concentrations (5, 10 and 18%) with/or without further ultra-sonication treatment at 35 kHz for 1 h. The pH values were lower in the ultra-sonicated samples in comparison with the non-ultra-sonicated samples (p<0.05). The values for texture traits were higher in the samples soaked in 10% saline solution with ultra-sonication in comparison with other remaining treatments or control (p<0.05). The sodium content in samples soaked in 10% saline solution with ultra-sonication was similar to that of the ones soaked in 18% saline solution without ultra-sonication. The higher flavor scores were also given for the ultra-sonicated samples in comparison with the control or non-ultra-sonicated ones. These results suggest that the application of ultra-sonication may produce a faster sodium penetration into baked eggs, simultaneously improves some textural traits (e.g., hardness) as well as flavor of the products.

Simultaneous Identification of 13 Foodborne Pathogens by Using Capillary Electrophoresis-Single Strand Conformation Polymorphism Coupled with Multiplex Ligation-Dependent Probe Amplification and Its Application in Foods.

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.

Kinetic Behavior of Salmonella on Low NaNO2 Sausages during Aerobic and Vacuum Storage.

This study evaluated the growth kinetics of Salmonella spp. in processed meat products formulated with low sodium nitrite (NaNO2). A 5-strain mixture of Salmonella spp. was inoculated on 25-g samples of sausages formulated with sodium chloride (NaCl) (1.0%, 1.25%, and 1.5%) and NaNO2 (0 and 10 ppm) followed by aerobic or vacuum storage at 10℃ and 15℃ for up to 816 h or 408 h, respectively. The bacterial cell counts were enumerated on xylose lysine deoxycholate agar, and the modified Gompertz model was fitted to the Salmonella cell counts to calculate the kinetic parameters as a function of NaCl concentration on the growth rate (GR; Log CFU/g/h) and lag phase duration (LPD; h). A linear equation was then fitted to the parameters to evaluate the effect of NaCl concentration on the kinetic parameters. The GR values of Salmonella on sausages were higher (p<0.05) with 10 ppm NaNO2 concentration than with 0 ppm NaNO2. The GR values of Salmonella decreased (p<0.05) as NaCl concentration increased, especially at 10℃. This result indicates that 10 ppm NaNO2 may increase Salmonella growth at low NaCl concentrations, and that NaCl plays an important role in inhibiting Salmonella growth in sausages with low NaNO2.

Mathematical Model for Predicting the Growth Probability of Staphylococcus aureus in Combinations of NaCl and NaNO2 under Aerobic or Evacuated Storage Conditions.

The objective of this study was to describe the growth patterns of Staphylococcus aureus in combinations of NaCl and NaNO2, using a probabilistic model. A mixture of S. aureus strains (NCCP10826, ATCC13565, ATCC14458, ATCC23235, and ATCC27664) was inoculated into nutrient broth plus NaCl (0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, and 1.75%) and NaNO2 (0, 15, 30, 45, 60, 75, 90, 105, and 120 ppm). The samples were then incubated at 4, 7, 10, 12 and 15℃ for up to 60 d under aerobic or vacuum conditions. Growth responses [growth (1) or no growth (0)] were then determined every 24 h by turbidity, and analyzed to select significant parameters (p<0.05) by a stepwise selection method, resulting in a probabilistic model. The developed models were then validated with observed growth responses. S. aureus growth was observed only under aerobic storage at 10-15℃. At 10-15℃, NaCl and NaNO2 did not inhibit S. aureus growth at less than 1.25% NaCl. Concentration dependency was observed for NaCl at more than 1.25%, but not for NaNO2. The concordance percentage between observed and predicted growth data was approximately 93.86%. This result indicates that S. aureus growth can be inhibited in vacuum packaging and even aerobic storage below 10℃. Furthermore, NaNO2 does not effectively inhibit S. aureus growth.

Extracellular vesicle-derived protein from Bifidobacterium longum alleviates food allergy through mast cell suppression.

BACKGROUND: The incidence of food allergies has increased dramatically during the last decade. Recently, probiotics have been studied for the prevention and treatment of allergic disease. OBJECTIVE: We examined whether Bifidobacterium longum KACC 91563 and Enterococcus faecalis KACC 91532 have the capacity to suppress food allergies. METHODS: B longum KACC 91563 and E faecalis KACC 91532 were administered to BALB/c wild-type mice, in which food allergy was induced by using ovalbumin and alum. Food allergy symptoms and various immune responses were assessed. RESULTS: B longum KACC 91563, but not E faecalis KACC 91532, alleviated food allergy symptoms. Extracellular vesicles of B longum KACC 91563 bound specifically to mast cells and induced apoptosis without affecting T-cell immune responses. Furthermore, injection of family 5 extracellular solute-binding protein, a main component of extracellular vesicles, into mice markedly reduced the occurrence of diarrhea in a mouse food allergy model. CONCLUSION: B longum KACC 91563 induces apoptosis of mast cells specifically and alleviates food allergy symptoms. Accordingly, B longum KACC 91563 and family 5 extracellular solute-binding protein exhibit potential as therapeutic approaches for food allergies.

Thymic Stromal Lymphopoietin Induction Is Mediated by the Major Whey Proteins α-Lactalbumin and ß-Lactoglobulin through the NF-κB Pathway in Immune Cells.

α-Lactalbumin and ß-lactoglobulin are two major whey proteins that specifically bind immunoglobulin E and are suspected as major allergens causing cow's milk allergy (CMA). Recent studies have shown that thymic stromal lymphopoietin is a critical factor linking at the interface of the body and environment to the T-helper 2 response. However, it is not known whether thymic stromal lymphopoietin expression is changed by α-lactalbumin and ß-lactoglobulin in immune cells. Using RT-PCR and ELISA, the present study was conducted to examine if intravenous injection of α-lactalbumin and ß-lactoglobulin increased pro-inflammatory cytokines, T-helper 2 cytokines, and thymic stromal lymphopoietin expression in several immune cells, including macrophages, mast cells, and keratinocytes. Results showed that α-lactalbumin and ß-lactoglobulin induced thymic stromal lymphopoietin, interleukin-6, and tumor necrosis factor-α expression. It was concluded that the allergenicity of α-lactalbumin and ß-lactoglobulin may be attributed to thymic stromal lymphopoietin induction, T-helper 2 cytokines, and pro-inflammatory cytokines.