Search Results (335)

Dehydration and storage conditions used to preserve dairy cultures in the industry may negatively impact their viability and functionality. This study investigated the effects of freeze-drying and storage on the metabolic activity of Lacticaseibacillus rhamnosus 73 (L73). The strain’s viability after freeze-drying and storage, its metabolic activity in cultured milk, and its performance as a ripening agent in miniature cheeses were evaluated. Neither the freeze-drying process nor the storage conditions negatively affected its viability, as L73 maintained its initially high levels (>10 log cfu mL⁻¹) throughout the storage period. L73 improved the overall quality of the cheeses, as a reduction in hydrophobic peptides (i.e., potential bitter peptides) was evidenced in cheese manufactured with L73. Furthermore, L73 exhibited protective properties, as evidenced by the decreased availability of compounds that could be used as energy sources by adventitious microorganisms (e.g., galactose, hippuric acid) and the increased production of lactic acid in both cultured milk and cheese. Full article

Microbial fermentation technology has emerged as a pivotal approach for enhancing ginseng efficacy through the transformation of active ingredient molecular structures. This paper reviews the impact of microbial fermentation on the structure–activity relationship of ginseng bioactive compounds and advances in its application. Bibliometric analysis indicates that Panax species (Panax ginseng, Panax notoginseng) are primarily fermented using lactic acid bacteria and Aspergillus spp., with research predominantly focused on conversion efficiency to rare ginsenosides (Compound K, Rg3, and Rh2). Specifically, this review details the biotransformation pathways of these rare ginsenosides and the resultant bioactivity enhancements. Additionally, it summarizes the effects of other microorganisms, such as fungal fruiting bodies, on additional ginseng constituents like polysaccharides and polyphenols. Microbial fermentation has been successfully implemented in functional products, including ginseng vinegar, wine, and fermented milk. This review subsequently examines these applications, emphasizing fermentation’s potential to enhance product functionality. However, challenges remain in strain screening, process standardization, and analysis of multi-component synergistic mechanisms. In summary, this review synthesizes recent advancements in understanding the mechanisms of microbial fermentation on ginseng and its translational applications in functional foods and pharmaceuticals. Full article

Subclinical mastitis is a critical disease affecting camel health and milk quality. However, research on shifts in milk bacterial communities following subclinical mastitis in camels is limited. We evaluated changes in bacterial communities following subclinical mastitis in Bactrian camels. Three portions of California Mastitis Test (CMT)-negative milk and five portions of CMT-positive milk were collected from each Jimunai County and Keping County using the CMT, and the bacterial community composition of the camel milk was analyzed using amplicon sequencing of the v34 region of the 16S rRNA gene. Subclinical mastitis induced genus-level differences in the core bacterial microbiota of Bactrian camel milk. To our knowledge, Delftia was identified in camel milk for the first time, predominantly in Jimunai County. Bacterial abundance in camel milk from Keping County was increased and altered. Alpha diversity analysis revealed that subclinical mastitis induced lower and higher bacterial abundance in milk from Jimunai County and Keping County, respectively, compared to that of healthy camels. Therefore, these findings provide direction for future research on pathogenic microorganisms for the prevention and control of subclinical mastitis in Bactrian camels. Full article

Selenium sulfide, the active ingredient of traditional antidandruff shampoos, is industrially produced from selenium dioxide (SeO₂) and hydrogen sulfide (H₂S) under acidic conditions. This reaction can also be carried out with natural H₂S and H₂S generated by sulfate-reducing bacteria (SRB). These bacteria are robust and, by relying on their conventional growth medium, also thrive in “waste” materials, such as a mixture of cabbage juice and compost on the one side, and a mixture of spoiled milk and mineral water on the other. In these mixtures, SRB are able to utilize the DL-lactate and sulfate (SO₄²⁻) present naturally and produce up to 4.1 mM concentrations of H₂S in the gas phase above a standard culture medium. This gas subsequently escapes the fermentation vessel and can be collected and reacted with SeO₂ in a separate compartment, where it yields, for instance, pure selenium sulfide, therefore avoiding the need for any cumbersome workup or purification procedures. Thus “harvesting” H₂S and similar (bio-)gases produced by the fermentation of organic waste materials by suitable microorganisms provides an elegant avenue to turn dirty waste into valuable clean chemical products of considerable industrial and pharmaceutical interest. Full article

The increasing interest in fermented foods stems from their health benefits, mediated by foodborne microorganisms. This study aimed to characterize the fermentative microbiota of Pecorino di Picinisco, a traditional Italian cheese made from ovine raw milk, and to evaluate the probiotic and technological potential of selected lactic acid bacteria strains. Three strains representative of the different species found (Lactococcus lactis, Lactiplantibacillus plantarum and Latilactobacillus curvatus) were chosen and analyzed. All three strains were able to adhere to human intestinal Caco-2 cells, were resistant to simulated in vitro digestion and significantly prolonged the lifespan of Caenorhabditis elegans, used as a simplified in vivo model, with respect to the commercial probiotic strain Lacticaseibacillus rhamnosus GG. The L. plantarum Pic37.4 strain was particularly promising; therefore, its cell-free supernatant was employed to evaluate the antimicrobial activity against indicator strains of foodborne and intestinal pathogens or spoilage bacteria. The results demonstrated the effectiveness of the supernatant against all strains tested, with the strongest effect on the intestinal pathogen enterotoxigenic Escherichia coli K88. In addition, the inhibitory effect on pathogen adhesion to intestinal mucosa was investigated on Caco-2 cells, resulting in a significant reduction in adhesion mediated by the L. plantarum Pic37.4 supernatant. The antimicrobial properties of the L. plantarum strain were confirmed in vivo in C. elegans. These promising results lay the ground for further investigations aimed at substantiating the probiotic and technological potential of the L. plantarum Pic37.4 investigated in this work. Full article

Microbial detection in milk is crucial for food safety and quality, as beneficial and harmful microorganisms can affect consumer health and dairy product integrity. Identifying and quantifying these microorganisms helps prevent contamination and spoilage. The study employs advanced molecular techniques to detect and quantify the genomic DNA for the target hydrolytic enzyme coding genes lipA and aprX based on the multi-align sequence conserved region, specific primer pair, and hydrolysis probes designed using the singleplex qPCR and multiplex qPCR. Cultured isolates and artificially contaminated sterilized ultra-high-temperature (UHT) milk were analyzed for their specificity, cross-reactivity, and sensitivity. The finding indicated that strains with lipA and aprX genes were amplified while the other strains were not amplified. This indicated that the designed primer pairs/probes were very specific to the target gene of interest. The specificity of each design primer pair was checked using SYBR Green qPCR using 16 different isolate strains from the milk sample. The quantification specificity of each strain target gene was deemed to be with a mean Ct value for positive pseudomonas strain > 16.98 ± 1.76 (p < 0.0001), non-pseudomonas positive strain ≥ 27.47 ± 1.25 (p < 0.0001), no Ct for the negative control and molecular grade water. The sensitivity limit of detection (LOD) analyzed based on culture broth and milk sample was >10⁵ and >10⁴ in PCR amplification while it was >10⁴ and >10³ in real-time qPCR, respectively. At the same time, the correlation regression coefficient of the standard curve based on the pure culture cell DNA as the DNA concentration serially diluted (20 ng/µL to 0.0002 ng/µL) was obtained in multiplex without interference and cross-reactivity, yielding R² ≥ 0.9908 slope (−3.2591) and intercepting with a value of 37, where the efficiency reached the level of 95–102% sensitivity reached up to 0.0002 ng/µL concentration of DNA, and sensitivity of microbial load was up to 1.2 × 10² CFU/mL. Therefore, multiplex TaqMan qPCR simultaneous amplification was considered the best method developed for the detection of the lipA and aprX genes in a single tube. This will result in developing future simultaneous (three- to four-gene) detection of spoilage psychrotrophic bacteria in raw milk. Full article

Mastitis is defined as mammary gland inflammation and is one of the most common and economically significant diseases affecting dairy cows. Bacteria are the most frequently reported agents responsible for mastitis, while other pathogens are often overlooked due to insufficient routine investigation. Incomplete diagnoses can result in inappropriate antimicrobial treatments, treatment failures, antimicrobial resistance, the spread of pathogens, and the recurrence of mastitis. Background/Objectives: This study aimed to investigate the presence of Staphylococcus spp. associated with Romanian buffalo mastitis on dairy farms in Western Romania via a bacteriological analysis of mastitis milk and determine antimicrobial susceptibility profiles. Methods: Bacterial culture was performed according to the guidelines described by the National Mastitis Council. Vitek 2 Compact systems (Bio Mérieux, France), with the GP ID cards, were used to confirm the species of the isolates. Antibiotic susceptibility testing was conducted by utilizing Vitek^® 2 preset antimicrobial card AST-GP79 Gram-positive Livestock WW. Results: Of all the milk samples (n = 115) analyzed, 83 were positive for Staphylococcus spp. (72.17%) and were evaluated for their antimicrobial susceptibility profiles. The most common microorganism found was S. aureus (n = 46; 55.42%), followed by S. hyicus (n = 28; 33.73%) and S. schleiferi (n = 9; 10.84%). These pathogens demonstrated significant resistance to the tetracycline, neomycin, benzylpenicillin, and erythromycin. Conclusions: Current control measures for mastitis caused by S. aureus are ineffective. A better understanding of the virulence factors in Romanian buffalo-adapted strains of S. aureus, their pathogenesis, and host immunological responses is essential for developing effective and sustainable non-antibiotic control tools such as vaccines, prophylactic therapies, and other innovative approaches. Full article

Processing of meat waste into meat and bone meal generates wastewater that must be properly treated to minimize its environmental impact. In addition to its high organic load, it contains microorganisms, including pathogens, that pose a threat to human health. In this study, wastewater from meat and bone meal production was treated using the Fenton process with a variable Fe²⁺/H₂O₂ mass ratio ranging from 1:2 to 1:10, followed by neutralization with lime milk. A microbiological analysis was performed on both the raw wastewater and the liquid fractions obtained after treatment, along with additional analyses of selected physicochemical parameters. The identification of isolated microorganisms was carried out using the MALDI-TOF MS technique. Qualitative analysis of the treated wastewater samples showed the presence of microorganisms belonging to the genera Staphylococcus, Enterococcus, Alcaligenes, and Pseudomonas. Staphylococcus aureus and Alcaligenes faecalis were present in each of the treated samples. The Fenton process effectively reduced the total number of microorganisms, with the lowest counts of 1.3 × 10² CFU/mL and 3.2 × 10² CFU/mL found in wastewater samples treated with Fe²⁺/H₂O₂ mass ratios of 1:8 and 1:10, which correlated with higher doses of hydrogen peroxide. Full article

Lactobacillus rhamnosus GG (LGG) is a common lactic acid bacteria used in the food industry with proven health benefits. Maintaining a high viability of probiotics during freeze drying and storage is crucial for their efficacy. The involvement of protectants and the optimization of operating conditions are promising techniques utilized to help bacteria microorganisms overcome environmental challenges. Although numerous studies have investigated the effectiveness of various protective agents in mitigating environmental stresses on bacterial cells and improving their survival during freeze drying, there is limited understanding of how freezing parameters impact the process by influencing ice crystal formation and bacterial cell microstructure. Therefore, this study systematically evaluates the effects of freeze-thawing and freeze-drying processes on the survival and metabolic activity of LGG. The results reveal that cell damage during freezing and freeze drying is a complex process influenced by a variety of physicochemical factors, including freezing conditions, sublimation and thawing processes, as well as the choice of cryoprotectants and reconstitution medium. Notably, freezing with water in liquid nitrogen at −196 °C resulted in the highest bacterial survival rate (90.94%) under short freezing durations, demonstrating the importance of freezing conditions. Freeze drying further reduced viability, with survival rates dropping to as low as 2% under suboptimal conditions. Interestingly, phosphate-buffered saline as a resuspension medium significantly increased the loss of viable LGG during both freezing and freeze drying. The addition of trehalose and skim milk as cryoprotectants enhanced survival to 15.17% post-freeze drying, emphasizing the role of protective agents in improving viability. This study provides novel insights into the critical role of freezing parameters and operational conditions in preserving probiotic viability, offering valuable guidelines for optimizing the freeze-drying process to maintain the functionality of probiotics. Full article

The use of low-temperature antibacterial technology is a processing method designed to preserve the biological activity of milk to the greatest extent. Traditional feeding and milking practices result in high levels of microbiological contamination of raw milk after extraction, mainly from cows and milking equipment, especially rubber cups. Ultrasonic treatment combined with antimicrobial agents combine cleaning and antibacterial technology, compared with traditional cleaning methods, more efficiently and in a environmentally friendly way. In this study, the technique was demonstrated to significantly reduce the total amount of bacteria in raw milk through simulation experiments on the surface of milking cups. It was shown that ultrasound-coupled slightly electrolytic water has a good potential for application in reducing bacterial contamination in the milk extraction process on farms. We investigated the synergistic mechanism of ultrasound (US) and slightly acidic electrolytic water (SAEW) and verified the bactericidal effect of milking cups. A 20 s treatment of milking cups with US (100 W) and SAEW (90 mg/L) led to an antibacterial rate of over 90%. The bactericidal mechanism causes fragmentation of the cell membrane of pathogenic bacteria, exudation of their intracellular contents such as nucleic acids and proteins, and increases in ROS. Full article

Breast milk is vital for infant survival, protecting against infections and strengthening the immune system. In addition to nutrients, breast milk contains beneficial microorganisms, antimicrobial peptides and proteins (APPs), including lactoferrin and lysozyme, and peptides such as defensins and cathelicidins that destroy harmful bacteria and regulate the neonatal immune response. Breast milk also promotes the growth of beneficial gut bacteria (Bacteroidaceae and Bifidobacteriaceae) while reducing harmful pathogens, fostering a healthy gut microbiome, and supporting long-term infant health. Traditionally, research on antimicrobial proteins and milk microbiota has been conducted in isolation. However, at the molecular level, these components do not function independently; they interact synergistically, influencing immunomodulation, inflammation, and the composition of the gut microbiome. Therefore, this review aims to provide an overview of the discovery and identification of APPs in breast milk, the dynamic relationship between the breast milk microbiota, and the potentiation of artificial feeding with supplemented formulas when breastfeeding is impossible, benefits on newborn immune systems, and even the benefits to breast tissue. Full article

During the preparation of beer wort, significant amounts of waste raw materials, such as brewers’ spent grain (BSG), are generated. In line with the zero-waste approach, a processing technology for BSG was developed to valorize this by-product. The developed method involves obtaining a BSG extract (plant-based milk), followed by filtration to remove insoluble residues and subsequent fermentation to produce vegan BSG-based yogurt-like products, with and without the addition of sucrose, as well as pectin, guar gum, and konjac gum as stabilizers. The samples were analyzed for pH, moisture and protein content, water activity (Aw), color, viscosity, and syneresis, and were also subjected to an organoleptic evaluation. Fermentation with starter cultures yielded BSG-based yogurt-like products with an optimal pH (~4.0), which, combined with Aw values below 0.95, ensures microbiological safety by inhibiting the growth of pathogenic and spoilage microorganisms. Due to phase separation, the use of stabilizers was necessary to achieve a yogurt-like texture. Their application also contributed to a reduction in syneresis—sometimes even preventing its occurrence—and led to an increase in viscosity, which ranged from 0.162 to 0.463 Pa·s, depending on the stabilizer used. The moisture content of fermented BSG extracts ranged from 88.2% to 91.7%. All samples showed similar protein content, approximately 50% on a dry matter basis. Furthermore, organoleptic assessment (5-point scale) revealed that sensory characteristics varied depending on the stabilizer and sugar used. The yogurt-like variant formulated with 0.5% pectin and 1% sucrose received the highest acceptance score (4.0), indicating good sensory quality. Full article

This study assessed the impact of farming systems on aflatoxin M1 (AFM1) content and the prevalence of mastitis-causing bacteria in goat milk. A total of 233 milk samples were collected from two Skopelos goat farms—one intensive and one extensive farm—and analyzed for AFM1 content using a competitive ELISA. An additional 219 samples from goats suspected of subclinical mastitis were tested for bacterial prevalence with microbial culturing. The results showed that AFM1 concentration was significantly higher in the intensive farming system (7.76 ± 0.76 ng/kg) than in the extensive farming system (3.78 ± 0.79 ng/kg), though it remained below the legal limit of 50 ng/kg. The main effects of season and year were not significant, though higher levels of AFM1 were observed during winter. The interaction effects of season–farming system and year–season–farming system on AFM1 levels were significant. The prevalence of mastitis-causing bacteria varied by system, with Streptococcus spp. being more common in the extensive farming system, and Staphylococcus aureus was more frequently detected in milk samples from the intensive farming system. Binomial regression indicated that both the farming system and lactation stage significantly influenced Streptococcus spp. prevalence (p = 0.05; OR = 1.9 and 2.7, respectively). It is concluded that the farming system affects those quality parameters in goat milk. Full article

Variations in ecological environments (including milk collection equipment and milk storage tanks in the pasture) and seasonal changes may contribute to raw milk contamination, thereby affecting food safety. The composition, structure, and relationships between raw milk and microbial communities in these environments are not well understood. In this study, 84 samples from spring and autumn in Luxian County, Yunnan Province, China, were collected for high-throughput sequencing technology. The results showed that the skin on the nipple surface and the environment (including the wiping samples of the automatic milking machine and the inner cover of the milk tank) had the greatest impact on microbial community composition in raw milk, followed by dung. In addition, microbial diversity in autumn samples was significantly higher, likely due to seasonal factors, including increased rainfall and reduced ultraviolet radiation. By analyzing the microbial community of raw milk and its environmental source, this study traced the origin of microorganisms in milk, providing insights for further exploration of the interaction between the pasture environment and raw milk microorganisms. Full article

The purpose of this study was to identify the microbial community of raw milk samples before and after UV-C irradiation and to establish fundamental data on UV-C treatment to improve the safety and shelf life of raw milk. Metagenomic analysis revealed that Lactococcus spp., Lactobacillus spp., and Staphylococcus spp. were the dominant genera in raw milk, while Pseudomonas spp. became more prevalent after 14 days of refrigerated storage. The microorganisms in raw milk were isolated using selective media and identified as Serratia quinivorans 4364 and Latilactobacillus curvatus DSM 20019. To compare the UV resistance of these microorganisms, Pseudomonas aeruginosa, Staphylococcus aureus, Lactococcus lactis, and Latilactobacillus curvatus were inoculated into sterilized milk and subjected to UV-C treatment. The reduction rates of P. aeruginosa were significantly lower than those of the other strains (S. aureus, L. lactis, and L. curvatus). These findings provide insights into the microbial distribution in raw milk and the degree of resistance to UV treatment, which can serve as fundamental data for the pasteurization of raw milk. Full article