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1.
Food Microbiol ; 109: 104143, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309444

RESUMO

The objective of the present study was to compare the growth of food-pathogens Listeria monocytogenes, Salmonella enterica, food spoilage Bacillus subtilis, an industrial milk product isolate, and spore-forming Paenibacillus in commercially available ultrahigh temperature processed (UHT) bovine milk and non-dairy, plant-based beverages (coconut, almond, cashew) stored at chilled and ambient temperatures (4 °C, 8 °C or 20 °C). Beverage samples were inoculated with a strain cocktail or individual strains of either Listeria or Salmonella, or Paenibacillus or Bacillus, respectively (approximately 1 × 103 CFU/mL). The findings indicate that the bacterial strains used in the study were capable of proliferating in plant-based beverages at higher rates than in bovine milk at 8 °C and 20 °C for Listeria and 20 °C for Salmonella and Paenibacillus, respectively. Bacillus subtilis grew equally fast in bovine milk and plant-based almond drink at 20 °C. No statistically significant difference (p > 0.05) in growth rates between different types of tested beverages was observed at 4 °C and at 8 °C for Listeria and Salmonella cocktails, respectively. These data suggest that plant-based beverages may present a significant risk for listeriosis and salmonellosis and post-opening recommendations should be carefully considered.


Assuntos
Bacillus , Listeria monocytogenes , Listeria , Paenibacillus , Animais , Leite/microbiologia , Microbiologia de Alimentos , Contagem de Colônia Microbiana , Esporos Bacterianos , Salmonella
2.
Food Microbiol ; 109: 104154, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309450

RESUMO

Wooden vats are used in the production of some traditional cheeses as the biofilms on wooden vat surfaces are known to transfer large quantities of microbes to cheese. However, very few studies have investigated the microbial composition of biofilms on newly developed wooden vats and how communities assemble and evolve. In the present study, the microbial communities of biofilms were characterized over the activation process on new wooden vats using amplicon sequencing of bacterial 16s rRNA and fungal internal transcribed spacer genes. Results showed that microbes from the whey effectively developed on wooden vats. Lactococcus was highly dominant throughout the vat activation process with substantial increases in the relative abundance of Acetobacter and Lactobacillus at the end of the vat activation (day 7). This was in contrast with fungal communities that stabilized early (day 1) and were dominated by Kluyveromyces. Predicted functions corresponded with the different stages of biofilm formation whereby functions associated with biofilm initiation were enriched on day 1 and those associated with growth and maturation were enriched on days 4 and 7. Microbial succession on wooden vat surfaces is expected to be reproducible based on the early onset and dominance of the deterministic process.


Assuntos
Queijo , Microbiota , Animais , Queijo/microbiologia , RNA Ribossômico 16S/genética , Leite/microbiologia , Microbiota/genética , Biofilmes
3.
Food Microbiol ; 109: 104150, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309452

RESUMO

Routine monitoring of foodborne pathogens such as Listeria monocytogenes in food processing environments are time-consuming necessities to ensure food safety. Alternative rapid diagnostic methods for pathogen detection are increasingly used, but often demand specialized equipment, making them unsuitable for on-site testing. This short communication describes the successful demonstration of combining the sample preparation method Matrix-Lysis with a chemiluminescent based detection platform (AquaSpark™) for detection of L. monocytogenes in milk and yogurt. The proposed method was evaluated against qPCR resulting in 100% relative specificity for both foodstuffs and a relative sensitivity of 100% for milk as well as 96% for yogurt for bacterial levels >1 CFU/ml. Only at very low initial bacterial concentrations (<1 CFU/ml) diverging results were found highlighting the advantages and limitations of both methods. While being less susceptible to contamination and false positive results from non-growing or dead cells, qPCR had a slightly lower overall detection limit. However, it has to be pointed out that qPCR has an increased analytical cost and also requires an additional 24 h analysis time. This study demonstrates the first successful application of a chemilumonogenic detection approach for L. monocytogenes in food that has a high potential for on-site testing.


Assuntos
Listeria monocytogenes , Animais , Listeria monocytogenes/genética , Microbiologia de Alimentos , Laticínios/microbiologia , Leite/microbiologia , Reação em Cadeia da Polimerase em Tempo Real , Iogurte
4.
Nutrients ; 14(21)2022 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-36364717

RESUMO

We conducted a study to determine the survival of bacterial cells under in vitro digestion. For this purpose, ice cream mixes were prepared: control, with 4% inulin, 2.5% inulin and 1.5% apple fiber and 4% apple fiber. Each inoculum (pH = 4.60 ± 0.05), containing 9 log cfu g-1 bacteria, at 5% (w/w) was added to the ice cream mixes (Lacticaseibacilluscasei 431, Lactobacillus acidophilus LA-5, Lacticaseibacillus paracasei L-26, Lacticaseibacillusrhamnosus, Bifidobacterium animalis ssp. lactis BB-12) and fermentation was carried out to pH 4.60 ± 0.05. The in vitro digestion method simulated the stages of digestion that occur in the mouth, stomach and small intestine under optimal controlled conditions (pH value, time and temperature). At each stage of digestion, the survival rate of probiotic bacteria was determined using the plate-deep method. As expected, in the oral stage, there was no significant reduction in the viability of the probiotic bacteria in any ice cream group compared to their content before digestion. In the stomach stage, Bifidobacterium animalis ssp. lactis BB-12 strain had the highest viable counts (8.48 log cfu g-1) among the control samples. Furthermore, a 4% addition of inulin to ice cream with Bifidobacterium BB-12 increased gastric juice tolerance and limited strain reduction by only 16.7% compared to the number of bacterial cells before digestion. Regarding ice cream samples with Bifidobacterium BB-12, replacing part of the inulin with apple fiber resulted in increased survival at the stomach stage and a low reduction in the bacterial population of only 15.6% compared to samples before digestion. At the stomach stage, the positive effect of the addition of inulin and apple fiber was also demonstrated for ice cream samples with Lacticaseibacilluscasei 431 (9.47 log cfu g-1), Lactobacillus acidophilus LA-5 (8.06 log cfu g-1) and Lacticaseibacillus paracasei L-26 (5.79 log cfu g-1). This study showed the highest sensitivity to simulated gastric stress for ice cream samples with Lacticaseibacillusrhamnosus (4.54 log cfu g-1). Our study confirmed that the 4% addition of inulin to ice cream increases the survival rate of L. casei and Bifidobacterium BB-12 in simulated intestinal juice with bile by 0.87 and 2.26 log cfu g-1, respectively. The highest viable count in the small intestine stage was observed in ice cream with L. acidophilus. The addition of inulin increased the survival of L. rhamnosus by 10.8% and Bifidobacterium BB-12 by about 22% under conditions of simulated in vitro digestion compared to their control samples. The survival rates of L. casei and L. paracasei were also highly affected by the 4% addition of apple fiber, where the increase under gastrointestinal passage conditions was determined to range from 7.86-11.26% compared to their control counterparts. In comparison, the lowest survival rate was found in the control ice cream with L. rhamnosus (47.40%). In our study at the intestinal stage, only five ice cream groups: a sample with 4% inulin and L. acidophilus, a control sample with Bifidobacterium BB12, a sample with 2.5% inulin and 1.5% apple fiber with Bifidobacterium BB12, a control sample with L. rhamnosus, a sample with 4% fiber and L. rhamnosus reported bacterial cell counts below 6 log cfu g-1 but higher than 5 log cfu g-1. However, in the remaining ice cream groups, viable counts of bacterial cells ranged from 6.11 to 8.88 log cfu g-1, ensuring a therapeutic effect. Studies have clearly indicated that sheep milk ice cream could provide a suitable matrix for the delivery of probiotics and prebiotics and contribute to intestinal homeostasis. The obtained results have an applicative character and may play an essential role in developing new functional sheep milk ice cream.


Assuntos
Bifidobacterium animalis , Sorvetes , Malus , Probióticos , Ovinos , Animais , Sorvetes/microbiologia , Inulina/farmacologia , Leite/microbiologia , Lactobacillus acidophilus , Fibras na Dieta , Digestão
5.
Molecules ; 27(21)2022 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-36364161

RESUMO

This manuscript aimed to optimise the encapsulation of Thymus capitatus essential oil into nanoemulsion. Response Surface Methodology results were best fitted into polynomial models with regression coefficient values of more than 0.95. The optimal nanoemulsion showed nanometer-sized droplets (380 nm), a polydispersity index less than 0.5, and a suitable Zeta potential (-10.3 mV). Stability results showed that nanoemulsions stored at 4 °C were stable with the lowest d3,2, PolyDispersity Index (PDI), and pH (day 11). Significant ameliorations in the capacity to neutralise DPPH radical after the encapsulation of the antimicrobial efficacy of thyme essential oil were recorded. S. typhimurium growth inhibition generated by nanoencapsulated thyme essential oil was 17 times higher than by bulk essential oil. The sensory analysis highlighted that the encapsulation of thyme essential oil improved enriched milk's sensory appreciation. Indeed, 20% of the total population attributed a score of 4 and 5 on the scale used for milk enriched with nanoemulsion. In comparison, only 11% attributed the same score to milk enriched with bulk essential oil. The novel nanometric delivery system presents significant interest for agroalimentary industries.


Assuntos
Anti-Infecciosos , Óleos Voláteis , Thymus (Planta) , Animais , Óleos Voláteis/farmacologia , Emulsões , Anti-Infecciosos/farmacologia , Leite/microbiologia
6.
PLoS One ; 17(10): e0276018, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36240215

RESUMO

The consumption of raw milk from dairy cows has caused multiple food-borne outbreaks of campylobacteriosis in the European Union (EU) since 2011. Cross-contamination of raw milk through faeces is an important vehicle for transmission of Campylobacter to consumers. This systematic review and meta-analysis, aimed to summarize data on the prevalence and concentration of Campylobacter in faeces of dairy cows. Suitable scientific articles published up to July 2021 were identified through a systematic literature search and subjected to screening and quality assessment. Fifty-three out of 1338 identified studies were eligible for data extraction and 44 were further eligible for meta-analysis. The pooled prevalence was calculated in two different meta-analytic models: a simple model based on one average prevalence estimate per study and a multilevel meta-analytic model that included all prevalence outcomes reported in each study (including different subgroups of e.g. health status and age of dairy cows). The results of the two models were significantly different with a pooled prevalence estimate of 29%, 95% CI [23-36%] and 51%, 95% CI [44-57%], respectively. The effect of sub-groups on prevalence were analyzed with a multilevel mixed-effect model which showed a significant effect of the faecal collection methods and Campylobacter species on the prevalence. A meta-analysis on concentration data could not be performed due to the limited availability of data. This systematic review highlights important data gaps and limitations in current studies and variation of prevalence outcomes between available studies. The included studies used a variety of methods for sampling, data collection and analysis of Campylobacter that added uncertainty to the pooled prevalence estimates. Nevertheless, the performed meta-analysis improved our understanding of Campylobacter prevalence in faeces of dairy cows and is considered a valuable basis for the further development of quantitative microbiological risk assessment models for Campylobacter in (raw) milk and food products thereof.


Assuntos
Infecções por Campylobacter , Campylobacter , Animais , Infecções por Campylobacter/epidemiologia , Infecções por Campylobacter/microbiologia , Infecções por Campylobacter/veterinária , Bovinos , Fezes/microbiologia , Feminino , Leite/microbiologia , Prevalência
7.
ScientificWorldJournal ; 2022: 7967569, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36187286

RESUMO

This study aimed to evaluate the microbial quality of raw milk along the milk value chain at Africa University (AU). Eighteen Holstein-Friesian cows were used in this experiment. A total of 270 milk samples were collected for laboratory analysis at three different stages, during milking (DM), from the bulk tank (BT), and at the dining hall (DH), to determine the total bacterial count (TBC), Escherichia coli, and Salmonella enterica. Samples were cultured in Petri dishes using an appropriate medium for 48 hours. The plate count method was used to determine the quantity of bacteria. Data were analyzed using GLM SPSS. The results indicated that TBC increased (P < 0.05) from one site to the next along the value chain, yet it undulates when measured over time. Escherichia. coli and S. enterica counts increased (P < 0.05) at the last site of collection and the highest counts were recorded in week two. In conclusion, the current study indicates the hygiene of the dairy parlor with very low TBC, E. coli, and S. enterica counts during milking and bulk tank storage and that the relationship between TBC and E. coli is nonlinear with respect to time.


Assuntos
Indústria de Laticínios , Leite , Animais , Bactérias , Carga Bacteriana , Bovinos , Indústria de Laticínios/métodos , Escherichia coli , Feminino , Leite/microbiologia
8.
Arch Microbiol ; 204(10): 656, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-36182984

RESUMO

This study aims to reveal initial bacterial consortia of Ezine PDO cheeses comprehensively by following a metagenomic approach. A total of 8 artisanal Ezine cheese samples were collected from the Bayramiç and Ezine districts of Çanakkale province of Turkey. Ezine cheese was found to contain Firmicutes, Bacteroidetes, and Proteobacteria phyla dominantly. Streptococcus, Lactococcus, and Lactobacillus genera dominated the microbiota with relative abundances of 4.47-56.07%, 7.33-20.34%, and 1.21-25.12%, respectively, followed by Bacteroides and Prevotella genera. Excluding two cheese samples obtained from the Ezine district, the most dominant species was Streptococcus thermophilus (8.24-54.34%). It was also found in greater proportions in the cheeses of the Bayramiç district. Unexpectedly, Lactobacillus graminis (11.50-23.63%) was the most abundant species in two samples collected from the Ezine district. However, lower bacterial diversity was determined in the samples collected from the Bayramiç district. The lowest species richness was 129 OTU-species in the cheeses from the Bayramiç district while the highest species richness was 267 OTU-species in cheeses from the Ezine district. In addition, the Simpson index was the highest in cheeses from the Ezine district, where different species were evenly distributed. Permutational multivariate analysis of variance tests also confirmed that the differences in the structure of bacterial consortia in cheeses from two different districts were statistically significant. This study will provide pioneer data for further investigations on the role of complex bacterial composition in maintaining and improving the quality and safety of Ezine cheese.


Assuntos
Queijo , Microbiota , Animais , Queijo/microbiologia , Microbiologia de Alimentos , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Leite/microbiologia , Streptococcus thermophilus/genética
9.
J Dairy Sci ; 105(12): 9995-10006, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36270870

RESUMO

Staphylococcus hominis, a member of the non-aureus staphylococci (NAS) group, is part of the human and animal microbiota. Although it has been isolated from multiple bovine-associated habitats, its relevance as a cause of bovine mastitis is currently not well described. To successfully colonize and proliferate in the bovine mammary gland, a bacterial species must be able to acquire iron from host iron-binding proteins. The aims of this study were (1) to assess the genetic diversity of S. hominis isolated from bovine quarter milk, rectal feces, and teat apices, and (2) to investigate the capacity of bovine S. hominis isolates belonging to these different habitats to utilize ferritin and lactoferrin as iron sources. To expand on an available collection of bovine S. hominis isolates (2 from quarter milk, 8 from rectal feces, and 19 from teat apices) from one commercial dairy herd, a subsequent single cross-sectional quarter milk sampling (n = 360) was performed on all lactating cows (n = 90) of the same herd. In total, 514 NAS isolates were recovered and identified by MALDI-TOF mass spectrometry; the 6 most prevalent NAS species were S. cohnii (33.9%), S. sciuri (16.7%), S. haemolyticus (16.3%), S. xylosus (9.6%), S. equorum (9.4%), and S. hominis (3.5%). A random amplified polymorphic DNA (RAPD) analysis was performed on 46 S. hominis isolates (19 from quarter milk, 8 from rectal feces, and 19 from teat apices). Eighteen distinct RAPD fingerprint groups were distinguished although we were unable to detect the presence of the same RAPD type in all 3 habitats. One S. hominis isolate of a distinct RAPD type unique to a specific habitat (8 from quarter milk, 3 from rectal feces, and 4 from teat apices) along with the quality control strain Staphylococcus aureus ATCC 25923 and 2 well-studied Staphylococcus chromogenes isolates ("IM" and "TA") were included in the phenotypical iron test. All isolates were grown in 4 types of media: iron-rich tryptic soy broth, iron-rich tryptic soy broth deferrated by 2,2'-bipyridyl, and deferrated tryptic soy broth supplemented with human recombinant lactoferrin or equine spleen-derived ferritin. The growth of the different strains was modified by the medium in which they were grown. Staphylococcus chromogenes TA showed significantly lower growth under iron-deprived conditions, and adding an iron supplement (lactoferrin or ferritin) resulted in no improvement in growth; in contrast, growth of S. chromogenes IM was significantly recovered with iron supplementation. Staphylococcus hominis strains from all 3 habitats were able to significantly utilize ferritin but not lactoferrin as an iron source to reverse the growth inhibition, in varying degrees, caused by the chelating agent 2,2'-bipyridyl.


Assuntos
Doenças dos Bovinos , Doenças dos Cavalos , Mastite Bovina , Infecções Estafilocócicas , Feminino , Humanos , Bovinos , Animais , Cavalos , Leite/microbiologia , Staphylococcus hominis , Lactação , Técnica de Amplificação ao Acaso de DNA Polimórfico/veterinária , Estudos Transversais , 2,2'-Dipiridil , Glândulas Mamárias Animais/microbiologia , Mastite Bovina/microbiologia , Infecções Estafilocócicas/veterinária , Fezes/microbiologia , Ferro , Ferritinas , Variação Genética , Doenças dos Bovinos/microbiologia
10.
J Dairy Sci ; 105(12): 9463-9475, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36270872

RESUMO

Phenyllactic acid (PLA) has been demonstrated to possess antibacterial activity and capacity to prolong food shelf life. However, studies on the performance of PLA in inhibiting Staphylococcus aureus and its effectiveness when applied to dairy products are largely lacking. Here, antibacterial activity (planktonic and biofilm states) of PLA against S. aureus CICC10145 (S. aureus_45) were investigated. The results showed that PLA inhibited growth of S. aureus_45 and formation of S. aureus_45 biofilm. Next, the antibacterial action target of PLA was uncovered from both physiological and phenotypic perspectives. The results showed that PLA decreased cell metabolic activity and cell viability, damaged cell membrane integrity, triggered leakage of intracellular contents (DNA, proteins, and ATP), and caused oxidative stress damage and morphological deformation of S. aureus_45. In practical application, the antibacterial activity of PLA against S. aureus_45 cells was further confirmed in skim milk and cheese as dairy food models, and the antibacterial effects can be adequately maintained during storage for 21 d, at least at 4°C. These findings suggested that PLA could be a potential candidate for controlling S. aureus outgrowth in dairy foods.


Assuntos
Queijo , Infecções Estafilocócicas , Animais , Staphylococcus aureus , Queijo/microbiologia , Leite/microbiologia , Infecções Estafilocócicas/veterinária , Antibacterianos/farmacologia , Poliésteres
11.
J Dairy Sci ; 105(12): 9439-9449, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36207177

RESUMO

Bacterial spores from raw milk that survive the pasteurization process are responsible for half of all the spoilage of fluid milk. Bactofugation has received more attention as a nonthermal method that can reduce the presence of bacterial spores in milk and with it the spoilage of fluid milk. The objective of this work was to determine the effectiveness of bactofugation in removing spores from raw milk and estimate the effect the spore removal could have on shelf-life of fluid milk. The study was conducted in a commercial fluid milk processing facility where warm spore removal was performed using one-phase bactofuge followed by warm cream separation and high temperature, short time pasteurization. Samples from different stages of fluid milk processing with and without the use of bactofuge were tested for total plate count, mesophilic spore count, psychrotolerant spore count (PSC), and somatic cell count. Results were evaluated to determine the count reductions during different stages of fluid milk processing and compare counts in fluid milk processed with and without bactofugation. Bactofugation on average reduced the total plate count by 1.81 ± 0.72 log cfu/mL, mesophilic spore count by 1.08 ± 0.71 log cfu/mL, PSC by 0.86 ± 0.59 log cfu/mL, and somatic cell count by 135,881 ± 43,942 cells/mL. Psychrotolerant spore count in final pasteurized skim milk processed with and without bactofugation was used to predict the shelf-life of the pasteurized skim milk using the Monte Carlo simulation model. Although PSC in the initial raw milk was already low (-0.63 ± 0.47 log cfu/mL), the predicted values from the simulation model showed that bactofugation would extend the shelf-life of pasteurized skim milk by approximately 2 d. The results of this study will directly help fluid milk processors evaluate the benefits of using bactofugation as an intervention in their plants, and also demonstrate the benefits of using mathematical modeling in decision making.


Assuntos
Leite , Pasteurização , Animais , Leite/microbiologia , Método de Monte Carlo , Contagem de Colônia Microbiana/veterinária , Esporos Bacterianos , Microbiologia de Alimentos
12.
Arch Microbiol ; 204(11): 680, 2022 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-36315293

RESUMO

Bovine mastitis is an important disease in dairy cows, and Staphylococcus aureus is the most prevalent microorganism. Bacteriophages are considered an alternative to treat bacterial infections due to antimicrobial resistance crisis. In this study, we isolated and characterized novel S. aureus temperate phages, namely B_UFSM4 and B_UFSM5, from bovine milk. The complete genomes of B_UFSM4 and B_UFSM5 have 41.396 bp and 41.829 bp, respectively. The viruses have double-stranded DNA and linear architecture. Phylogenic similarity was observed by proteome with Staphylococcus phage phiPV83, CN125 and JS01. Therefore, the phages were classified into the family Siphoviridae, genus Biseptimavirus and order Caudovirales. In the host range, the B_UFSM4 and B_UFSM5 had lytic activity of 45.8% and 54.16%, respectively, inclusive on isolates from Staphylococcus sciuri and Rothia terrae. Thus, in this study, species novel of S. aureus temperate phages was isolated and characterized, these phages reveal similarities to each other; however, they are distinct from other species of S. aureus phages of the family Siphoviridae.


Assuntos
Mastite Bovina , Siphoviridae , Infecções Estafilocócicas , Animais , Feminino , Bovinos , Staphylococcus aureus/genética , Leite/microbiologia , Infecções Estafilocócicas/veterinária , Infecções Estafilocócicas/microbiologia , Fagos de Staphylococcus/genética , Mastite Bovina/microbiologia , Siphoviridae/genética
13.
Foodborne Pathog Dis ; 19(11): 750-757, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36301255

RESUMO

Milk is a putrescible commodity that is extremely prone to microbial contamination. Primarily, milk and dairy products are believed to be easily contaminated by pathogenic microorganisms, including Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus. The microbiological quality of raw milk and dairy products regarding foodborne pathogens is of paramount importance due to concern of human health. In this study 400 buffalo raw milk samples were screened for assessing the prevalence of L. monocytogenes, Salmonella spp., and S. aureus. This study implemented uniplex-polymerase chain reaction (u-PCR) and multiplex-polymerase chain reaction (m-PCR) assays for the fast simultaneous detection of these pathogens comparing to the conventional culturing methods. Raw milk samples were found contaminated with the prevalence of 2.2%, 4.0%, and 14.2% for L. monocytogenes, Salmonella spp., and S. aureus, respectively. These pathogens were detected with the optimized polymerase chain reaction assays after 6 h of enrichment. u-PCR and m-PCR demonstrated the limit of detection as 104, 102, and 10 cells/mL after 6, 12, 18, and 24 h for each culture of the pathogens. A high sensitivity (10 colony-forming unit [CFU]/mL) of the m-PCR protocol was noted. The developed protocol is a cost-effective and rapid method for the simultaneous detection of pathogens associated with raw milk and dairy industries.


Assuntos
Listeria monocytogenes , Leite , Animais , Humanos , Leite/microbiologia , Búfalos , Staphylococcus aureus/genética , Listeria monocytogenes/genética , Salmonella/genética , Reação em Cadeia da Polimerase Multiplex/métodos , Microbiologia de Alimentos
14.
Trop Anim Health Prod ; 54(6): 356, 2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36269471

RESUMO

In this study, we evaluated the main risk factors for the occurrence of bovine mastitis, in the southeastern of Pará, in the Brazilian Amazon. We surveyed 91 dairy farmers to identify management practices and bovine breed characteristics. From each farm, 50 mL of milk sample was collected for microbiological analysis and somatic cell count (SCC). Depending on the management practices and breed, a logit model was used to determine the odds ratio of subclinical mastitis (SCM) occurrence. In irrigated pastures, an SCM-associated risk factor, the occurrence of SCM was 5.03 times higher than that in the non-irrigated pastures. Similarly, in Girolando breed herds, the occurrence of SCM increased by 5.8 times compared to the crossbred herds. Moreover, the occurrence of mastitis was 33 times higher in farms using common cloths for drying teats than in farms using paper towels. Therefore, adoption of better management practices can lead to SCC reduction, milk quality improvement and a guarantee to contain SCC within prescribed Brazilian limits for the Amazon region.


Assuntos
Doenças dos Bovinos , Mastite Bovina , Animais , Bovinos , Feminino , Contagem de Células/veterinária , Indústria de Laticínios , Mastite Bovina/epidemiologia , Mastite Bovina/microbiologia , Leite/microbiologia , Prevalência , Fatores de Risco , Brasil
15.
Toxins (Basel) ; 14(10)2022 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-36287980

RESUMO

Bacterial secondary metabolites play a major role in the alleviation of diseases; however, the cytotoxicity of other metabolites cannot be ignored as such metabolites could be detrimental to human cells. Three Staphylococci strains Staphylococcus aureus, staphylococcus epidermidis and staphylococcus saprophyticus were used in the experiments. These strains are well known to cause hospital and community-acquired infections. Secondary metabolites from S. aureus isolated from milk of cows with clinical features of mastitis (swollen udders and the production of watery clotted milk), S. saprophyticus (ATCC 35552), and S. epidermidis (ATCC 51625) were exposed to a minimal medium then screened using Gas Chromatography High-Resolution Time-of-flight Mass Spectrometry (GC-HRTOF-MS) and identified with Nuclear Magnetic Resonance (NMR). From S. epidermidis, two compounds were isolated: oleamide and methyl palmitate; three from S. aureus, including fluoranthene, 3-methyl-2-phenyl-1H-pyrrole, and cyclo(L-Leu-L-Propyl); while S. saprophyticus yielded succinic acid, 1,2,6-hexantriol, veratramine, and 4-methyl-pentyl-amine. The secondary metabolites were tested for cytotoxicity using the Vero cell line. Fluoranthene exhibited toxicity with an LC50 of 0.0167 mg/mL to Vero cells, while the other metabolites did not. Methyl palmitate was the least toxic of all of the metabolites. The results imply that none of the compounds, except fluoranthene, pose any danger to human cells.


Assuntos
Infecções Estafilocócicas , Staphylococcus , Chlorocebus aethiops , Feminino , Bovinos , Humanos , Animais , Staphylococcus/metabolismo , Staphylococcus aureus , Células Vero , Ácido Succínico/metabolismo , Infecções Estafilocócicas/microbiologia , Leite/microbiologia , Staphylococcus epidermidis , Aminas , Pirróis
16.
Food Res Int ; 160: 111707, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36076456

RESUMO

Izmir Brined Tulum (IBT) Cheese is a traditional semi hard cheese produced in the Aegean region of Türkiye. Lactic acid bacteria (LAB) isolates from IBT cheese samples taken during manufacture and from mature IBT cheeses were investigated for their acid producing capability with the aim of detecting LAB strains responsible for acid production in IBT cheese. Forty two out of 216 isolates decreased the pH of milk to 5.0 or below in 18 h at 37 °C or 42 °C. 16S rRNA Sanger sequencing revealed the presence of LAB species that had not been detected in IBT cheese previously and, indeed, were identified for the first time as the primary acid producers. The majority of these acid producing isolates were identified as putative Streptococcus lutetiensis/Streptococcus infantarius subsp. infantarius (Sii). Further analysis by sequencing the groES/groEL genes of these isolates established that they were Sii. The remaining isolates from cheese samples taken during manufacture were identified as Streptococcus macedonicus, S. thermophilus, Lactococcus lactis subsp. lactis, Lactobacillus delbrueckii subsp. sunkii and L. delbrueckii subsp. indicus and, from mature cheeses, as Enterococcus faecalis and L. delbrueckii subsp. sunkii. Pulsed-field gel electrophoresis (PFGE) results revealed a large genetic diversity amongst the Sii isolates recovered from the IBT cheeses. It was also established that the Sii strains exhibited efficient and consistent acidification ability equivalent to S. thermophilus. Whole-genome sequencing (WGS) and comparative genome analysis of the representative Sii AYB210 strain provided further insights. More specifically, the genome of AYB210 differed from the previously sequenced African dairy isolate Sii CJ18 and the human isolate ATCC®BAA-102™. Modifications in the lactose operon, which may be an indicator of dairy adaptation, were identified and a high number of CRISPR spacers and putative bacteriocin, virulence factor and antibiotic resistance genes were also detected.


Assuntos
Queijo , Lactobacillales , Lactococcus lactis , Animais , Queijo/microbiologia , Humanos , Lactobacillales/genética , Lactobacillus , Lactococcus lactis/genética , Leite/microbiologia , RNA Ribossômico 16S/genética , Streptococcus
17.
PLoS One ; 17(9): e0267992, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36107863

RESUMO

Although bacterial detection by 16S rRNA gene amplicon DNA sequencing is a widely-applied technique, standardized methods for sample preparation and DNA extraction are needed to ensure accuracy, reproducibility, and scalability for automation. To develop these methods for bovine bulk milk, we assembled and tested a bacterial cell mock community (BCMC) containing bacterial species commonly found in milk. The following protocol variations were examined:: BCMC enumeration (colony enumeration or microscopy), sample volume (200 µl to 30 ml), sample storage condition (frozen in PBS or 25% glycerol or exposure to freeze-thaw cycles), cell lysis method (bead-beating, vortex, enzymatic), and DNA extraction procedure (MagMAX Total, MagMAX CORE, and MagMAX Ultra 2.0, with and without either Proteinase K or RNase A). Cell enumeration by microscopy was more accurate for quantification of the BCMC contents. We found that least 10 mL (≥ 104 cells in high quality milk) is needed for reproducible bacterial detection by 16S rRNA gene amplicon DNA sequencing, whereas variations in storage conditions caused minor differences in the BCMC. For DNA extraction and purification, a mild lysis step (bead-beating for 10 s at 4 m/s or vortexing at 1800 rpm for 10 s) paired with the MagMAX Total kit and Proteinase K digestion provided the most accurate representation of the BCMC. Cell lysis procedures conferred the greatest changes to milk microbiota composition and these effects were confirmed to provide similar results for commercial milk samples. Overall, our systematic approach with the BCMC is broadly applicable to other milk, food, and environmental samples therefore recommended for improving accuracy of culture-independent, DNA sequence-based analyses of microbial composition in different habitats.


Assuntos
Microbiota , Leite , Animais , Bactérias , Bovinos , DNA Bacteriano/genética , Endopeptidase K , Glicerol , Microbiota/genética , Leite/microbiologia , RNA Ribossômico 16S/genética , Reprodutibilidade dos Testes , Ribonuclease Pancreático
18.
Arch Microbiol ; 204(10): 619, 2022 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-36098848

RESUMO

Probiotic attributes of lactic acid bacteria isolated from goat and sheep milk samples were analysed by culturing them on an MRS agar medium. The most potential isolates, GMB24 and SMB16, were identified by biochemical tests which had ability to tolerate different concentrations of acid and bile and phenol resistance. They were further identified as Enterococcus faecium GMB24 and Enterococcus hirae SMB16 by 16S rRNA gene sequencing approach. The probiotic potential of the isolates GMB24 and SMB16 were recorded including antimicrobial activity against pathogenic bacteria viz., Escherichia coli (MTCC118), Staphylococcus aureus (MTCC7443), Pseudomonas aeruginosa (MTCC424), Listeria monocytogens (MTCC657) and Salmonella typhimurium (MTCC733), and antibiotic susceptibility test. The isolates SMB16 and GMB24 exhibited a higher zone of inhibition against P. aeruginosa (19.00 ± 0.57 mm) and S. aureus (25.66 ± 0.88 mm), respectively. The data from these experiments were used for the principal component analysis (PCA) to assess the survivability of the isolates under different factors. The heatmap generated in this study clustered the bacterial isolates based on their phenotype properties. Further, immunomodulating activities of these probiotic bacteria were tested on neutrophil adhesion test, haemagglutinating antibody titer and delayed-type hypersensitivity. Probiotic E. faecium GMB24 and E. hirae SMB16, at 109 cells/mL doses per day, increased the neutrophil adhesion, haemagglutinating antibody titer and DTH in comparison to the untreated control group. The isolates showed negative test for haemolytic and gelatinase activities and hence were considered safe. E. faecium GMB24 and E. hirae SMB16 were shown to have high probiotic potential and immune-stimulant action.


Assuntos
Enterococcus faecium , Probióticos , Animais , Enterococcus faecium/genética , Streptococcus faecium ATCC 9790/genética , Cabras , Leite/microbiologia , Probióticos/farmacologia , RNA Ribossômico 16S/genética , Ovinos , Staphylococcus aureus/genética
19.
Int J Food Microbiol ; 381: 109910, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36063683

RESUMO

Listeria monocytogenes, as a food-associated pathogen, is able to develop biofilms on different surfaces of food contact, which seriously threatens food safety. Phenyllactic acid (PLA) exhibits excellent inhibitory effects on many bacterial strains including L. monocytogenes. Our study aimed to investigate effects of PLA on L. monocytogenes biofilms and its growth in milk and on spiced beef. Biofilm biomass was measured by the microplate method and biofilm structure was observed by electron microscopy. Growth of L. monocytogenes in food samples was determined by colony counting. Results from the agar dilution method demonstrated that L. monocytogenes 10403S had a PLA minimum inhibitory concentration (MIC) value of 6 mg/ml. Sub-inhibitory concentrations of PLA could inhibit biofilm formation by reducing the secretion of exopolysaccharides and extracellular proteins in L. monocytogenes. PLA at concentrations above 1/2MIC could destroy mature biofilms of L. monocytogenes by decreasing the exopolysaccharides and extracellular proteins in the biofilm framework. Both swimming and swarming motilities of L. monocytogenes were inhibited by PLA. The hemolytic activity of L. monocytogenes was inactivated by PLA. However, the capacity to attach and invade Caco-2 cells was not affected by PLA. The results displayed that PLA had no effect on the expression of genes associated with motility, but reduced the expression level of the hly gene encoding Listeria hemolysin. When added to ultra-high temperature (UHT) whole and pasteurized milk, PLA at 3 mg/ml inhibited L. monocytogenes growth through 14 days of storage at 4 °C. PLA at concentrations ≥3 mg/ml significantly reduced L. monocytogenes counts on spiced beef samples during storage. PLA has potential as an alternative antimicrobial to control L. monocytogenes contamination and its biofilms in food industry.


Assuntos
Listeria monocytogenes , Ágar/metabolismo , Animais , Biofilmes , Células CACO-2 , Bovinos , Proteínas Hemolisinas , Humanos , Lactatos , Leite/microbiologia , Poliésteres/farmacologia
20.
J Appl Genet ; 63(4): 771-782, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36066834

RESUMO

MicroRNAs (miRNAs) as post-transcriptionally regulators of gene expression have been shown to be critical regulators to fine-tuning immune responses, besides their criteria for being an ideal biomarker. The regulatory role of miRNAs in responses to most mastitis-causing pathogens is not well understood. Gram-positive Streptococcus uberis (Str. uberis), the leading pathogen in dairy herds, cause both clinical and subclinical infections. In this study, a system biology approach was used to better understand the main post-transcriptional regulatory functions and elements of bovine mammary gland response to Str. uberis infection. Publicly available miRNA-Seq data containing 50 milk samples of the ten dairy cows (five controls and five infected) were retrieved for this current research. Functional enrichment analysis of predicted targets revealed that highly confident responsive miRNAs (4 up- and 19 downregulated) mainly regulate genes involved in the regulation of transcription, apoptotic process, regulation of cell adhesion, and pro-inflammatory signaling pathways. Time series analysis showed that six gene clusters significantly differed in comparisons between Str. uberis-induced samples with controls. Additionally, other bioinformatic analysis, including upstream network analysis, showed essential genes, including TP53 and TGFB1 and some small molecules, including glucose, curcumin, and LPS, commonly regulate most of the downregulated miRNAs. Upregulated miRNAs are commonly controlled by the most important genes, including IL1B, NEAT1, DICER1 enzyme and small molecules including estradiol, tamoxifen, estrogen, LPS, and epigallocatechin. Our study used results of next-generation sequencing to reveal key miRNAs as the main regulator of gene expression responses to a Gram-positive bacterial infection. Furthermore, by gene regulatory network (GRN) analysis, we can introduce the common upregulator transcription factor of these miRNAs. Such milk-based miRNA signature(s) would facilitate risk stratification for large-scale prevention programs and provide an opportunity for early diagnosis and therapeutic intervention.


Assuntos
Mastite Bovina , MicroRNAs , Infecções Estreptocócicas , Feminino , Bovinos , Animais , Mastite Bovina/genética , Mastite Bovina/microbiologia , Glândulas Mamárias Animais/metabolismo , Lipopolissacarídeos/metabolismo , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/veterinária , Leite/microbiologia , MicroRNAs/genética
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