Lactic Acid Bacteria (LAB) regulate and maintain the stability of healthy microbial flora, inhibit the adhesion of pathogenic bacteria and promote the colonization of beneficial micro‐organisms. The ...drug resistance and pathogenicity of Salmonella enteritis SE47 isolated from retail eggs were investigated. Meanwhile, Enterococcus faecalis L76 and Lactobacillus salivarius LAB35 were isolated from intestine of chicken. With SE47 as indicator bacteria, the diameters of L76 and LAB35 inhibition zones were 12 mm and 8·5 mm, respectively, by agar inhibition circle method, which indicated that both of them had inhibitory effect on Salmonella, and L76 had better antibacterial effect; two chicken‐derived lactic acid bacteria isolates and Salmonella SE47 were incubated with Caco‐2. The adhesion index of L76 was 17·5%, which was much higher than that of LAB35 (10·21%) and SE47 (4·89%), this experiment shows that the higher the bacteriostatic effect of potential probiotics, the stronger the adhesion ability; then Caco‐2 cells were incubated with different bacteria, and the survival of Caco‐2 cells was observed by flow cytometry. Compared with Salmonella SE47, the results showed that lactic acid bacteria isolates could effectively protect Caco‐2 cells; finally, after different bacteria incubated Caco‐2 cells, according to the cytokine detection kit, the RNA of Caco‐2 cells was extracted and transcribed into cDNA, then detected by fluorescence quantitative PCR, the results showed that L76 could protect Caco‐2 cells from the invasion of Salmonella SE47, with less cell membrane rupture and lower expression of MIF and TNF genes. Therefore, the lactic acid bacteria isolates can effectively inhibit the adhesion of Salmonella and protect the integrity of intestinal barrier.
Significance and Impact of the Study: We evaluated the effect of Lactobacillus from chicken on Salmonella. The results showed that both Enterococcus faecalis L76 and Lactobacillus salivarius LAB35 could effectively inhibit Salmonella SE47, and the inhibitory effect of L76 was better than LAB35. Chicken derived lactic acid bacteria can effectively protect the integrity of cell membrane from Salmonella invasion by adhering to cells. Lactobacillus can effectively antagonize the immune regulation of Salmonella in vitro. It was found that L76 had better immunomodulatory effect than LAB35.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Biogenic amines (BAs) are molecules, which can be present in foods and, due to their toxicity, can cause adverse effects on the consumers. BAs are generally produced by microbial decarboxylation of ...amino acids in food products. The most significant BAs occurring in foods are histamine, tyramine, putrescine, cadaverine, tryptamine, 2-phenylethylamine, spermine, spermidine, and agmatine. The importance of preventing the excessive accumulation of BAs in foods is related to their impact on human health and food quality. Quality criteria in connection with the presence of BAs in food and food products are necessary from a toxicological point of view. This is particularly important in fermented foods in which the massive microbial proliferation required for obtaining specific products is often relater with BAs accumulation. In this review, up-to-date information and recent discoveries about technological factors affecting BA content in foods are reviewed. Specifically, BA forming-microorganism and decarboxylation activity, genetic and metabolic organization of decarboxylases, risk associated to BAs (histamine, tyramine toxicity, and other BAs), environmental factors influencing BA formation (temperature, salt concentration, and pH). In addition, the technological factors for controlling BA production (use of starter culture, technological additives, effects of packaging, other non-thermal treatments, metabolizing BA by microorganisms, effects of pressure treatments on BA formation and antimicrobial substances) are addressed.
In this study, we addressed the challenge of excessive fluorescence background in bacterial colony Raman detection and aimed to achieve rapid identification of colonies. To overcome this issue, we ...employed a combination of droplet microcavity and label-free Surface Enhanced Raman Spectroscopy (SERS) technologies for spectroscopic analysis of five species of lactic acid bacteria (LAB) colonies during fermentation. This approach, coupled with Supported Vector Machine (SVM) and K-Nearest Neighbors (KNN) machine learning algorithms, facilitated the identification and analysis of spectral data. Comparing the results with conventional bacterial colony Raman spectra, the SERS spectra exhibited clear peaks, a higher and more stable signal-to-noise ratio, and noticeable spectral differences between various colonies, overcoming the limitations of insufficient fluorescence background. Moreover, the detection speed was notably enhanced, each SERS spectrum requires only 0.5 s, and the acquisition of the 100 spectral data points necessary for one bacterial colony is accomplished in less than 1 min. The SVM algorithm demonstrated a bacterial colony identification rate exceeding 95%, while the KNN algorithm achieved a rate surpassing 90%. These findings highlight the practical importance of using droplet microcavity combined with label-free SERS technology for quick and robust identification of the bacterial colonies.
•Droplet optical microcavity combined with label-free SERS technology for direct ultra-fast identification of colonies.•The process does not require additional processing of the colonies and can complete data collection within 1 min.•Excellent results for the identification of lactic acid bacteria colonies for yogurt fermentation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lactic acid bacteria (LAB) are critical in kimchi fermentation. This study determined the effect of temperature on the growth of 11 predominant LAB (five psychrotrophic and six mesophilic strains) ...isolated from kimchi and analyzed their growth behavior using a kinetic model to understand changes in LAB communities during kimchi fermentation. The modified Gompertz model was more suitable for the growth of kimchi LAB rather than the logistic model in terms of RMSE, AICc, R2, adjusted R2, Af and Bf. Latilactobacillus sakei KCKM 0001 and Leuconostoc mesenteroides KCKM 0008 rapidly grew at all temperatures (5, 10, 15, 20, 25, 30, and 37 °C) among the strains analyzed for growth characteristics using the modified Gompertz model. Additionally, the growth of psychrotrophic strains was more active than that of the mesophilic strains, excluding L. sakei KCKM 0001 and Leu. mesenteroides KCKM 0008 at kimchi fermentation temperatures of 5–10 °C. The differences observed in the lag phase and maximum specific growth rate at each temperature showed a trend consistent with previously reported dominant LAB at kimchi fermentation temperatures. The predictive modeling results showed that the changes in LAB communities during kimchi fermentation could be explained by their growth behavior at different temperatures.
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•Modified Gompertz model was suitable for predicting growth behavior of LAB at different temperatures.•Changes in LAB communities during kimchi fermentation could be explained by growth kinetic modeling.•This method could be used to understand microbial changes in other fermented food.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Kimchi is a traditional Korean fermented vegetable that is stored and fermented at low temperatures. However, kimchi lactic acid bacteria (LAB) are typically isolated under mesophilic conditions, ...which may be inappropriate for isolating the diverse LAB. Therefore, this study investigated the suitable conditions for isolating various LAB from kimchi. Here, LAB were isolated from four kimchi samples using MRS, PES, and LBS media and varying isolation temperatures (30, 20, 10, and 5℃). Then, MRS was selected as the suitable medium for LAB isolation. A comparison of culture-dependent and culture-independent approaches indicated that 5°C was not a suitable isolation temperature. Thus, the number and diversity of LAB were determined at 30, 20, and 10℃ using 12 additional kimchi samples to elucidate the effect of isolation temperature. With the exception of two samples, most samples did not substantially differ in LAB number. However, Leuconostoc gelidum, Leuconostoc gasicomitatum, Leuconostoc inhae, Dellaglioa algida, Companilactobacillus kimchiensis, Leuconostoc miyukkimchii, Leuconostoc holzapfelii, and Leuconostoc carnosum were isolated only at 10 and 20℃. The growth curves of these isolates, except Leu. holzapfelii and Leu. carnosum, showed poor growth at 30℃. This confirmed their psychrotrophic characteristics. In Weissella koreensis, which was isolated at all isolation temperatures, there was a difference in the fatty acid composition of membranes between strains that could grow well at 30℃ and those that could not. These findings can contribute to the isolation of more diverse psychrotrophic strains that were not well isolated under mesophilic temperatures.
Lactic acid bacteria (LAB) are the most frequently used probiotics in fermented foods and beverages and as food supplements for humans or animals, owing to their multiple beneficial features, which ...appear to be partially associated with their antioxidant properties. LAB can help improve food quality and flavor and prevent numerous disorders caused by oxidation in the host. In this review, we discuss the oxidative stress tolerance, the antioxidant capacity related herewith, and the underlying mechanisms and signaling pathways in probiotic LAB. In addition, we discuss appropriate methods used to evaluate the antioxidant capacity of probiotic LAB. The aim of the present review is to provide an overview of the current state of the research associated with the oxidative stress tolerance and antioxidant capacity of LAB.
Studies on the development of non-dairy probiotic foods and beverages are emerging. The optimal Lactobacillus and carbon resources were screened to improve the viability of probiotics in blueberry ...pomace. During fermentation, the total titratable acid and the viable counts were measured and peaked at 24 h, 15.75 mM and 11.59 Log CFU mL−1 respectively. Lactic acid content increased from 2.361 mg mL−1 to 6.334 mg mL−1, while citric acid content was decreased significantly. Additionally, the antioxidant activity was improved, which may be attributed to the increase of total phenols and flavonoids up to 4629.21 μg GAE mL−1 and 404.99 μg RE mL−1. Simulated gastrointestinal digestion in vitro showed that the total polyphenols were decreased slightly, while anthocyanins were increased. We also studied the cholesterol-lowing capability of fermented BPL and found that the cholesterol-clearance rate could reach 67.17%. Moreover, through mice weight-loaded swimming experiments, we observed that the physical strength of mice fed a fermented juice for one month was significantly better than that of the control group (p < 0.05). Therefore, this study provides a high value application of blueberry pomace and the fermented blueberry pomace with probiotics as a new type of probiotic food can furnish potentially value to human health.
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•Mixed fermented blueberry pomace by probiotics improves the content of the total phenols, flavonoids and inoxidizability.•Fermented blueberry pomace has certain effect on cholesterol clearance.•Fermented blueberry pomace shows great influence on anti-fatigue capability on weight-loaded swimming in mice.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Fermented milk replacer (FMR) feeding prevented severe diarrhea in newborn calves challenged with rotavirus.•Probiotic treatment reduced histopathological lesions of enteritis in the intestinal ...mucosa of the challenged calves.•FMR feeding reduced the incidence of enteritis and the associated mortality in dairy calves.
Diarrhea is a major cause of death in calves and this is linked directly to economic loss in the cattle industry. Fermented milk replacer (FMR) has been used widely in clinical settings for calf feeding to improve its health and growth. However, the protective efficacy of FMR on calf diarrhea remains unclear. In this study, we verified the preventive effects of FMR feeding on calf diarrhea using an experimental infection model of bovine rotavirus (BRV) in newborn calves and a field study in dairy farms with calf diarrhea. In addition, we evaluated the protective efficacy of lactic acid bacteria-supplemented milk replacer (LAB-MR) in an experimental infection model. In the experimental infection, calves fed FMR or high-concentrated LAB-MR had diarrhea, but the water content of feces was lower and more stable than that of calves fed normal milk replacer. The amount of milk intake also decreased temporarily, but recovered immediately in the FMR– and LAB-MR–fed calves. As compared with the control calves, FMR– or LAB-MR–fed calves showed less severe or reduced histopathological lesions of enteritis in the intestinal mucosa. In a field study using dairy calves, FMR feeding significantly reduced the incidence of enteritis, mortality from enteritis, duration of a series of treatment for enteritis, number of consultations, and cost of medical care for the disease. These results suggest that feeding milk replacer–based probiotics to calves reduces the severity of diarrhea and tissue damage to the intestinal tract caused by BRV infection and provides significant clinical benefits to the prevention and treatment of calf diarrhea.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The increasing concern of consumers about food quality and safety and their rejection of chemical additives has promoted the breakthrough of the biopreservation field and the development of studies ...on the use of beneficial bacteria and their metabolites as potential natural antimicrobials for shelf life extension and enhanced food safety. Control of foodborne pathogens in meat and meat products represents a serious challenge for the food industry which can be addressed through the intelligent use of bio-compounds or biopreservatives. This article aims to systematically review the available knowledge about biological strategies based on the use of lactic acid bacteria to control the proliferation of undesirable microorganisms in different meat products. The outcome of the literature search evidenced the potential of several strains of lactic acid bacteria and their purified or semi-purified antimicrobial metabolites as biopreservatives in meat products for achieving longer shelf life or inhibiting spoilage and pathogenic bacteria, especially when combined with other technologies to achieve a synergistic effect.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nitrite is still regarded as essentially undesirable in foods. Therefore, it is necessary to keep its concentration under control for food safety. The current study was conducted to evaluate the ...ability of two reference lactic acid strains to deplete nitrite. Lactobacillus acidophilus ROO52 and Streptococcus thermophiles YC-180 were examined in De Man Rogosa and Sharpe (MRS) and M17 broth with standard sodium nitrite at 0.10 mg /mL and 1 mL (10-8 cells per mL) for each of the reference strains to determine the ability of these strains to eliminate nitrite during the fermentation period. A control group, MRS and M17 broth and standard nitrite without inoculum were used. The nitrite depletion was determined by a UV-Vis spectrophotometer. After 48 hours of fermentation, there were significant differences between residual nitrite levels of broth inoculated by Streptococcus thermophiles YC-180 compared to control and Lactobacillus acidophilus ROO52. Streptococcus thermophiles YC-180 depleted nitrite levels significantly (P˂0.05) from the initial concentration (0.10 mg/ml) to 0.02 mg/ml with a percentage (45%) after 48 hours compared to control and Lactobacillus acidophilus ROO52, which depleted nitrite levels from the initial concentration of 0.10 mg/ml to 0.04 mg/ml with a percentage (22.5%) after 48 hours. In conclusion, Streptococcus thermophiles YC-180 was more effective at nitrite depletion than Lactobacillus acidophilus ROO52. The reduction of nitrite occurs due to acid production and the enzymatic action of these bacteria.
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