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1.
Microb Cell Fact ; 22(1): 16, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36670385

RESUMO

The large application potential of microbiomes has led to a great need for mixed culture methods. However, microbial interactions can compromise the maintenance of biodiversity during cultivation in a reactor. In particular, competition among species can lead to a strong disequilibrium in favor of the fittest microorganism. In this study, an invert emulsion system was designed by dispersing culture medium in a mixture of sunflower oil and the surfactant PGPR. Confocal laser scanning microscopy revealed that this system allowed to segregate microorganisms in independent droplets. Granulomorphometric analysis showed that the invert emulsion remains stable during at least 24 h, and that the introduction of bacteria did not have a significant impact on the structure of the invert emulsion. A two-strain antagonistic model demonstrated that this invert emulsion system allows the propagation of two strains without the exclusion of the less-fit bacterium. The monitoring of single-strain cultures of bacteria representative of a cheese microbiota revealed that all but Brevibacterium linens were able to grow. A consortium consisting of Lactococcus lactis subsp. lactis biovar diacetylactis, Streptococcus thermophilus, Leuconostoc mesenteroides, Staphylococcus xylosus, Lactiplantibacillus plantarum and Carnobacterium maltaromaticum was successfully cultivated without detectable biotic interactions. Metabarcoding analysis revealed that the system allowed a better maintenance of alpha diversity and produced a propagated bacterial consortium characterized by a structure closer to the initial state compared to non-emulsified medium. This culture system could be an important tool in the field of microbial community engineering.


Assuntos
Queijo , Lactococcus lactis , Emulsões , Bactérias , Interações Microbianas , Biodiversidade , Queijo/microbiologia , Microbiologia de Alimentos
2.
Biosensors (Basel) ; 13(1)2023 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-36671944

RESUMO

Frequent outbreaks of food-borne pathogens, particularly E. coli O157:H7, continue to impact human health and the agricultural economy tremendously. The required cell count for this pathogenic strain of E. coli O157:H7 is relatively low and hence it is vital to detect at low colony forming unit (CFU) counts. Available detection methods, though sensitive, fall short in terms of timeliness and often require extensive sample processing. To overcome these limitations, we propose a novel magneto-plasmonic nanosensor (MPnS) by integrating surface plasmon resonance (SPR) properties with spin-spin magnetic relaxation (T2 MR) technology. We engineered MPnS by encapsulating several gold nanoparticles (GNPs) within the polymer-coating of iron oxide nanoparticles (IONPs). First, the polyacrylic acid (PAA)-coated IONPs were synthesized using a solvent precipitation method, then gold chloride solution was used to synthesize GNPs and encapsulate them within the PAA-coatings of IONPs in one step. A magnetic separation technique was used to purify the MPnS and the presence of GNPs within IONPs was characterized using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and other spectroscopic methods. The synthesized MPnS exhibits MR relaxation properties while possessing amplified optical properties than conventional GNPs. This allows for rapid and ultrasensitive detection of E. coli O157:H7 by SPR, T2 MR, and colorimetric readout. Experiments conducted in simple buffer and in milk as a complex media demonstrated that our MPnS-based assay could detect as low as 10 CFUs of this pathogenic strain of E. coli O157:H7 in minutes with no cross-reactivity. Overall, the formulated MPnS is robust and holds great potential for the ultrasensitive detection of E. coli O157:H7 in a simple and timely fashion. Moreover, this platform is highly customizable and can be used for the detection of other foodborne pathogens.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Nanopartículas Metálicas , Humanos , Animais , Microbiologia de Alimentos , Ouro/química , Nanopartículas Metálicas/química , Leite , Técnicas Biossensoriais/métodos
3.
Int J Mol Sci ; 24(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36675060

RESUMO

Soil-borne Neosartorya spp. are the highly resilient sexual reproductive stage (teleomorph) of Aspergillus spp. Fungi of this genus are relevant components of root-associated microbial community, but they can also excrete mycotoxins and exhibit great resistance to high temperatures. Their ascospores easily transfer between soil and crops; thus, Neosartorya poses a danger to horticulture and food production, especially to the postharvest quality of fruits and vegetables. The spores are known to cause spoilage, mainly in raw fruit produce, juices, and pulps, despite undergoing pasteurization. However, these fungi can also participate in carbon transformation and sequestration, as well as plant protection in drought conditions. Many species have been identified and included in the genus, and yet some of them create taxonomical controversy due to their high similarity. This also contributes to Neosartorya spp. being easily mistaken for its anamorph, resulting in uncertain data within many studies. The review discusses also the factors shaping Neosartorya spp.'s resistance to temperature, preservatives, chemicals, and natural plant extracts, as well as presenting novel solutions to problems created by its resilient nature.


Assuntos
Temperatura Alta , Neosartorya , Microbiologia de Alimentos , Esporos Fúngicos , Horticultura
4.
BMC Microbiol ; 23(1): 27, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36690941

RESUMO

BACKGROUND: Listeria monocytogenes are Gram-positive rods, which are the etiological factor of listeriosis. L. monocytogenes quickly adapts to changing environmental conditions. Since the main source of rods is food, its elimination from the production line is a priority. The study aimed to evaluate the influence of selected stress factors on the growth and survival of L. monocytogenes strains isolated from food products and clinical material. RESULTS: We distinguished fifty genetically different strains of L. monocytogenes (PFGE method). Sixty-two percent of the tested strains represented 1/2a-3a serogroup. Sixty percent of the rods possessed ten examined virulence genes (fbpA, plcA, hlyA, plcB, inlB, actA, iap, inlA, mpl, prfA). Listeria Pathogenicity Island 1 (LIPI-1) was demonstrated among 38 (76.0%) strains. Majority (92.0%) of strains (46) were sensitive to all examined antibiotics. The most effective concentration of bacteriophage (inhibiting the growth of 22 strains; 44.0%) was 5 × 108 PFU. In turn, the concentration of 8% of NaCl was enough to inhibit the growth of 31 strains (62.0%). The clinical strain tolerated the broadest pH range (3 to 10). Five strains survived the 60-min exposure to 70˚C, whereas all were alive at each time stage of the cold stress experiment. During the stress of cyclic freezing-defrosting, an increase in the number of bacteria was shown after the first cycle, and a decrease was only observed after cycle 3. The least sensitive to low nutrients content were strains isolated from frozen food. The high BHI concentration promoted the growth of all groups. CONCLUSIONS: Data on survival in stress conditions can form the basis for one of the hypotheses explaining the formation of persistent strains. Such studies are also helpful for planning appropriate hygiene strategies within the food industry.


Assuntos
Listeria monocytogenes , Listeriose , Humanos , Microbiologia de Alimentos , Listeriose/microbiologia , Virulência/genética , Fatores de Virulência/genética , Proteínas de Bactérias/genética
5.
Food Microbiol ; 111: 104194, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36681398

RESUMO

Outbreaks of Salmonella and Shiga-toxin producing Escherichia coli (STEC) linked to wheat flour led to increased interest in characterizing the fate of Salmonella and STEC on wheat during processing. Tempering is the stage of wheat processing where water is added to toughen the bran prior to milling, which has the potential to influence pathogen behavior on the kernels. This study aimed to quantify changes in the numbers of STEC and Salmonella inoculated onto soft red winter wheat, and to observe potential changes in the distribution of the pathogens on the surface of kernels during tempering. Lab-scale tempering experiments were conducted to quantify the water activity of and bacterial populations on wheat grain at various time points during 16 h of tempering. The highest water activity observed throughout 16 h of tempering was 0.88. There was no significant change (p > 0.05) in numbers of Salmonella, STEC, or native mesophiles. Using confocal microscopy, observation of Salmonella and STEC cells expressing mCherry on wheat kernels showed an even distribution of inoculated cells, though the localization of cells on kernels did not change significantly after tempering. Even though the environment was not favorable for pathogen replication on grain, the population remained stable, suggesting that disinfection of the kernels prior to milling could reduce food safety concerns in flour.


Assuntos
Escherichia coli Shiga Toxigênica , Triticum/microbiologia , Farinha/microbiologia , Microbiologia de Alimentos , Salmonella , Grão Comestível , Água
6.
Food Microbiol ; 111: 104196, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36681400

RESUMO

All foods carry microbes, many of which are harmless, but foods can also carry pathogens and/or microbial indicators of contamination. Limited information exists on the co-occurrence of microbes of food safety concern and the factors associated with their presence. Here, a population-based repeated cross-sectional design was used to determine the prevalence and co-occurrence of Escherichia coli, Klebsiella spp., Salmonella spp. and Vibrio spp. in key food commodities - chicken, pork, prawns, salmon and leafy greens. Prevalence in 1,369 food samples for these four target bacterial genera/species varied, while 25.6% of all samples had at least two of the target bacteria and eight different combinations of bacteria were observed as co-occurrence profiles in raw prawns. Imported frozen chicken was 6.4 times more likely to contain Salmonella than domestic chicken, and imported salmon was 5.5 times more likely to be contaminated with E. coli. Seasonality was significantly associated with E. coli and Klebsiella spp. contamination in leafy greens, with higher detection in summer and autumn. Moreover, the odds of Klebsiella spp. contamination were higher in summer in chicken and pork samples. These results provide insight on the bacterial species present on foods at retail, and identify factors associated with the presence of individual bacteria, which are highly relevant for food safety risk assessments and the design of surveillance programmes.


Assuntos
Escherichia coli , Salmonella , Animais , Estudos Transversais , Inocuidade dos Alimentos , Galinhas/microbiologia , Bactérias/genética , Fatores de Risco , Microbiologia de Alimentos , Contaminação de Alimentos/análise
7.
Lett Appl Microbiol ; 76(1)2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36688747

RESUMO

Escherichia coli O157: H7 is a representative foodborne pathogen that causes haemorrhagic colitis, bloody diarrhea, and fatal haemolytic uraemic syndrome. Previously, only conventional heat treatment was used to pasteurised food; however, this method decreases food quality, including colour change, denatures proteins, and causes lipid oxidation. Therefore, emerging technologies to inactivate pathogens in food that affect food quality minimally have been researched and developed. This review aims to compile research since 2018 and briefly describe the inactivation mechanisms of emerging technologies such as microwave, radio frequency, ohmic heating, superheated steam, ionising radiation (gamma irradiation, electron beam, and X-rays), high pressure, ultraviolet light, pulsed light, ultrasound, gas treatment, plasma, and combination treatments. Pulsed electric field and electrolysed water were excluded because few research papers were published after 2018. In addition, the shortcomings of emerging technologies in the control of E. coli O157: H7 and the directions for emerging technology research are presented. Taking advantage of emerging technologies with many benefits will significantly improve food safety.


Assuntos
Escherichia coli O157 , Humanos , Escherichia coli O157/efeitos da radiação , Radiação Ionizante , Inocuidade dos Alimentos , Temperatura Alta , Diarreia , Microbiologia de Alimentos , Contagem de Colônia Microbiana
8.
Lett Appl Microbiol ; 76(1)2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36688773

RESUMO

The purpose of this study was to determine the effect of the culture method on the resistance of Salmonella Typhimurium in low water activity foods to storage, plasma, and dry heat. Whole black peppers were used as the model food. S. Typhimurium cultured in liquid broth (tryptic soy broth) or solid agar (tryptic soy agar) and inoculated on whole black pepper was stored or treated with cold plasma or dry heat. Inactivation of S. Typhimurium cultured in liquid medium was higher in all the treatments. Liquid-cultured S. Typhimurium showed higher DPPP = O (diphenyl-1-pyrenylphosphine oxide) values compared to the solid-cultured S. Typhimurium after plasma or dry heat treatment. Furthermore, the unsaturated fatty acid and saturated fatty acid ratio (USFA/SFA) was significantly (P < 0.05) reduced from 0.41 to 0.29 when S. Typhimurium was cultured on solid agar. These results suggested that the use of food-borne pathogens cultured on solid agar is more suitable for low water activity food pasteurization studies.


Assuntos
Piper nigrum , Salmonella enterica , Salmonella typhimurium/fisiologia , Ágar , Temperatura Alta , Sorogrupo , Microbiologia de Alimentos , Água , Contagem de Colônia Microbiana , Salmonella enterica/fisiologia
9.
Lett Appl Microbiol ; 76(1)2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36688780

RESUMO

Cronobacter sakazakii is an opportunistic foodborne pathogen in powdered infant formula (PIF) associated with several foodborne outbreaks. Biofilms of C. sakazakii in the PIF manufacturing plant may be a source of contamination, but information on the treatment of these biofilms is limited. This study investigated the inactivation of C. sakazakii biofilms on three food contact surfaces (stainless steel, silicone, and PVC) using high voltage atmospheric cold plasma (HVACP) applied as a dielectric barrier discharge in a 10:90 air: helium modified atmosphere. After the 90 s  of cold plasma exposure at 40 kV, C. sakazakii was reduced by ∼3 log CFU/coupon comparing to without cold plasma treatments. HVACP treatment caused cell shrinkage, fragmentation of the cell membrane, and leakage of cytoplasm. The inactivation of the cells on the surface was confirmed by live/dead staining. These above-mentioned results indicate the antibiofilm efficacy of HVACP on C. sakazakii isolates on various food contact surfaces.


Assuntos
Cronobacter sakazakii , Cronobacter , Gases em Plasma , Humanos , Lactente , Microbiologia de Alimentos , Biofilmes , Fórmulas Infantis
10.
Anal Chim Acta ; 1239: 340679, 2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36628706

RESUMO

BACKGROUND: s: To overcome the limitation of polymerase chain reaction (PCR), isothermal amplification methods such as thermophilic helicase-dependent amplification (tHDA) have been developed. However, formation of primer dimer due to the single amplification temperature are major problems of tHDA. When cross-dimerization of forward and reverse primer occurred, false-positive results can be found on the lateral flow assay (LFA) which is one of the major detection methods widely used as a point of care diagnosis. Therefore, specific method of detecting only the target amplicon is required. RESULTS: In this study, a tHDA-based CRISPR/Cas12a system was developed to detect low levels of Escherichia coli O157:H7 in fresh salad mix without the false-positive results produced by primer dimers. For the comparison of the effect in eliminating false-positive results by CRISPR/Cas12a system, LFA was also evaluated. The tHDA-based CRISPR/Cas12a system detected as low as 101 CFU/mL E. coli O157:H7 in bacterial pure culture. In LFA false-positive results were produced due to the primer dimer, whereas the primer dimer produced by tHDA was not detected in the CRISPR/Cas12a system. These results indicated that the CRISPR/Cas12a system eliminated the formation of primer dimer. In fresh salad mix, the tHDA-based CRISPR/Cas12a system combined with the filter concentration method detected 103 CFU/g E. coli O157:H7. CONCLUSION: This study was the first to amplify stx2 of E. coli O157:H7 with tHDA as an isothermal amplification method and detected the amplicon without false-positive results by combining tHDA with CRISPR/Cas12a. Therefore, this study showed great potential for detecting low levels of E. coli O157:H7 present in fresh salad mix.


Assuntos
Escherichia coli O157 , Escherichia coli O157/genética , Sistemas CRISPR-Cas , Reação em Cadeia da Polimerase/métodos , Microbiologia de Alimentos
11.
Int J Mol Sci ; 24(2)2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36674823

RESUMO

Three killer toxins that were previously investigated, one excreted by Kluyveromyces wickerhamii and two by different strains of Wickerhamomyces anomalus, were produced at the pilot scale, lyophilized and characterized, and the formulates were assessed for their zymocidial effect against Brettanomyces bruxellensis spoilage yeast. A comparative analysis allowed the evaluation of the minimum inhibitory concentration (MIC) against a sensitive strain. Fungicidal and fungistatic concentrations were used to evaluate the cytocidal effect using a cytofluorimetric approach that confirmed the lethal effect of all lyophilized formulates against B. bruxellensis spoilage yeasts. Moreover, the potential killer toxins' cytotoxicity against human intestinal cells (Caco-2) were evaluated to exclude any possible negative effect on the consumers. Finally, the effective lethal effect of all three lyophilized killer toxins toward B. bruxellensis sensitive strain were tested. The results indicated that all of them acted without dangerous effects on the human epithelial cells, opening the way for their possible commercial application. In particular, D15 showed the lowest MIC and the highest activity, was evaluated also in wine, revealing a strong reduction of Brettamonyces yeast growth and, at the same time, a control of ethyl phenols production.


Assuntos
Brettanomyces , Toxinas Biológicas , Vinho , Humanos , Células CACO-2 , Leveduras , Toxinas Biológicas/farmacologia , Microbiologia de Alimentos
12.
Food Res Int ; 163: 112183, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36596125

RESUMO

Soybeans are an important plant-based food but its beany flavor and anti-nutritional factors limit its consumption. Fermentation is an effective way to improve its flavor and nutrition. Furu is a popular fermented soybean curd and mainly manufactured in Asia, which has been consumed for thousands of years as an appetizer because of its attractive flavors. This review first classifies furu products on the basis of various factors; then, the microorganisms involved in its fermentation and their various functions are discussed. The mechanisms for the formation of aroma and taste compounds during fermentation are also discussed; and the microbial metabolites and their bioactivities are analyzed. Finally, future prospects and challenges are introduced and further research is proposed. This information is needed to protect the regional characteristics of furu and to regulate its consistent quality. The current information suggests that more in vivo experiments and further clinical trials are needed to confirm its safety and the microbial community needs to be optimized and standardized for each type of furu to improve the production process.


Assuntos
Alimentos de Soja , Alimentos de Soja/análise , Fermentação , Soja/metabolismo , Microbiologia de Alimentos , Percepção Gustatória
13.
Can J Vet Res ; 87(1): 51-58, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36606037

RESUMO

Enterococci are environmental pathogens that can cause bovine mastitis, which is treated with macrolides, one of which is erythromycin (ERY). The aim of this study was to compare the characteristics of high-level erythromycin-resistant (HLER) Enterococcus faecalis (E. faecalis) isolates from bulk tank milk of 4 dairy companies, identified as A to D, in order to assess the threat to public health. Although isolates from company D showed the highest prevalence of E. faecalis, the prevalence of HLER E. faecalis in isolates from company A showed a significant difference. A total of 149 of the 301 HLER E. faecalis isolates showed the highest rate of resistance to tetracycline. In the distribution of antimicrobial resistance genes, 147 isolates carried the ermB gene alone and 2 isolates carried both ermA and ermB genes. Also, 72 and 60 isolates carried both tetM and tetL genes and the tetM gene alone, respectively, and 38 isolates carried the optrA gene. The prevalence of both aac(6')Ie-aph(2″)-la and ant(6')-Ia genes was the highest and 104 isolates harbored the Int-Tn gene carrying the Tn916/1545-like transposon. Although the distribution of the e rmB gene showed no significant difference among dairy companies, the prevalence of other resistance genes and transposons showed significant differences among dairy companies. Virulence genes were highly conserved in the HLER E. faecalis isolates. Our results indicated that there were significant differences in phenotypic and genotypic characteristics of HLER E. faecalis isolates in milk from 4 different dairy companies. A structured management protocol by companies and constant monitoring are therefore necessary to minimize public health hazards.


Les entérocoques sont des agents pathogènes environnementaux qui peuvent causer la mammite bovine, qui est traitée avec des macrolides, dont l'érythromycine (ERY). Le but de cette étude était de comparer les caractéristiques des isolats d'Enterococcus f aecalis (E. faecalis) hautement résistants à l'érythromycine (HLER) provenant du lait de réservoir en vrac de quatre entreprises laitières, identifiées comme A à D, afin d'évaluer la menace pour santé publique. Bien que les isolats de la société D aient montré la prévalence la plus élevée d'E. faecalis, la prévalence d'E. faecalis HLER dans les isolats de la société A montrait une différence significative. Un total de 149 des 301 isolats d'E. faecalis HLER ont montré le taux le plus élevé de résistance à la tétracycline. Dans la distribution des gènes de résistance aux antimicrobiens, 147 isolats portaient le gène ermB seul et deux isolats portaient à la fois les gènes ermA et ermB. En outre, 72 et 60 isolats portaient à la fois les gènes tetM et tetL et le gène tetM seul, respectivement, et 38 isolats portaient le gène optrA. La prévalence des gènes aac(6')Ie-aph(2″)-la et ant(6')-Ia était la plus élevée et 104 isolats portaient le gène Int-Tn portant le transposon de type Tn916/1545. Bien que la distribution du gène ermB n'ait montré aucune différence significative entre les entreprises laitières, la prévalence d'autres gènes de résistance et transposons a montré des différences significatives entre les entreprises laitières. Les gènes de virulence étaient hautement conservés dans les isolats d'E. faecalis HLER. Nos résultats ont indiqué qu'il y avait des différences significatives dans les caractéristiques phénotypiques et génotypiques des isolats d'E. faecalis HLER dans le lait de quatre entreprises laitières différentes. Un protocole de gestion structuré par les entreprises et une surveillance constante sont donc nécessaires pour minimiser les risques pour la santé publique.(Traduit par Docteur Serge Messier).


Assuntos
Farmacorresistência Bacteriana , Enterococcus faecalis , Eritromicina , Leite , Animais , Bovinos , Feminino , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Enterococcus faecalis/genética , Eritromicina/farmacologia , Testes de Sensibilidade Microbiana/veterinária , Leite/microbiologia , República da Coreia/epidemiologia , Contaminação de Alimentos , Microbiologia de Alimentos
14.
Biosens Bioelectron ; 224: 115075, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36641877

RESUMO

To explore the superiority of multifunctional nanocomposites and realize the joint-detection of foodborne pathogens, an immersible amplification dip-stick immunoassay (DSIA) was exploited for the sensitive detection of Salmonella typhimurium (S. typhi) and Escherichia coli O157:H7 (E. coli O157:H7). Saving for the basic colorimetric performance, the reporter molecule of CoFe2O4 (CFO) possesses multivalent elements (Co2+/3+, Fe2+/3+) as well as multifunction of superior catalase-like activity and magnetic properties. By dint of the catalytic activity of CFO, a directly immersible amplification can be simply achieved to endure the DSIA with an intensive signal and a dual-visible mode for the determination of S. typhi and E. coli O157:H7. In virtue of the magnetic separation and enrichment capability of the CFO, the DSIA can perform a matrix-interference-free detection and obtain a dynamic detection range of 102-108 CFU/mL and a low assay limit of 102 CFU/mL. Moreover, the DSIA has reasonable recovery rates for contamination monitoring of two target bacteria in milk and beef samples. Our research provides a persuasive supplement for the application of multifunctional nanocomposites in the ongoing dip-stick immunoassay and an alternative strategy for the efficient detection of foodborne pathogens.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Animais , Bovinos , Salmonella typhimurium , Escherichia coli O157/genética , Imunoensaio , Leite/microbiologia , Microbiologia de Alimentos
15.
BMC Microbiol ; 23(1): 14, 2023 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-36639757

RESUMO

BACKGROUND: Tetragenococcus (T.) halophilus is a common member of the microbial consortia of food fermented under high salt conditions. These comprises salty condiments based on soy or lupine beans, fish sauce, shrimp paste and brined anchovies. Within these fermentations this lactic acid bacterium (LAB) is responsible for the formation of lactic and other short chain acids that contribute to the flavor and lower the pH of the product. In this study, we investigated the transcriptomic profile of the two T. halophilus strains TMW 2.2254 and TMW 2.2256 in a lupine moromi model medium supplied with galactose. To get further insights into which genomic trait is important, we used a setup with two strains. That way we can determine if strain dependent pathways contribute to the overall fitness. These strains differ in the ability to utilize L-arginine, L-aspartate, L-arabinose, D-sorbitol, glycerol, D-lactose or D-melibiose. The lupine moromi model medium is an adapted version of the regular MRS medium supplied with lupine peptone instead of casein peptone and meat extract, to simulate the amino acid availabilities in lupine moromi. RESULTS: The transcriptomic profiles of the T. halophilus strains TMW 2.2254 and TMW 2.2256 in a lupine peptone-based model media supplied with galactose, used as simulation media for a lupine seasoning sauce fermentation, were compared to the determine potentially important traits. Both strains, have a great overlap in their response to the culture conditions but some strain specific features such as the utilization of glycerol, sorbitol and arginine contribute to the overall fitness of the strain TMW 2.2256. Interestingly, although both strains have two non-identical copies of the tagatose-6P pathway and the Leloir pathway increased under the same conditions, TMW 2.2256 prefers the degradation via the tagatose-6P pathway while TMW 2.2254 does not. Furthermore, TMW 2.2256 shows an increase in pathways required for balancing out the intracellular NADH/NADH+ ratios. CONCLUSIONS: Our study reveals for the first time, that both versions of tagatose-6P pathways encoded in both strains are simultaneously active together with the Leloir pathway and contribute to the degradation of galactose. These findings will help to understand the strain dependent features that might be required for a starter strain in lupine moromi.


Assuntos
Enterococcaceae , Microbiologia de Alimentos , Lupinus , Enterococcaceae/genética , Enterococcaceae/metabolismo , Fermentação , Galactose/metabolismo , Glicerol , Lupinus/microbiologia , NAD/metabolismo , Peptonas/metabolismo , Sorbitol/metabolismo , Transcriptoma
16.
World J Microbiol Biotechnol ; 39(3): 77, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36642748

RESUMO

In the food sector, the formation of biofilms as a result of microbial adherence on food-grade surfaces causes a major problem resulting in significant economic losses. Thereby, this work aimed to elaborate a biodegradable film using chitosan (CS-film) and reinforce its antiadhesion activity by incorporating pelargonium, clove, thyme, and cinnamon essential oils (EOs). Firstly, the antibacterial activity of these EOs alone and combined against four foodborne bacteria were analyzed by the microdilution method. Synergism was observed in the case of EOs combination. Secondly, the physicochemical characteristics and antiadhesion behavior of the CS-films were assessed by the contact angle method and ESEM, respectively. Results revealed that the EOs mixture treatment impacted considerably the physicochemical characteristics of the CS-film and reduced its qualitative and quantitative hydrophobicity. Moreover, the treated CS-film showed a strong antiadhesion behavior against Enterococcus hirae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus with percentages of non-covered surface equal to 97.65 ± 1.43%, 98.76 ± 0.32%, 99.68 ± 0.28%, and 95.63 ± 1.32% respectively. From all these results, the CS-film treated with the mixture of EOs presents a great potential for application as surface coating and food packaging preventing microbial adhesion and thus, avoiding food contamination and spoilage.


Assuntos
Quitosana , Óleos Voláteis , Óleos Voláteis/farmacologia , Quitosana/farmacologia , Microbiologia de Alimentos , Bactérias , Antibacterianos/farmacologia , Escherichia coli , Testes de Sensibilidade Microbiana
17.
Talanta ; 255: 124203, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36565526

RESUMO

A one-step immunoassay based on filtration was presented, which used microbeads for target analyte detection and filters with appropriate pore sizes to distinguish the complexity of target analyte and microbeads. For effective bacterial detection, the microbead size and the filter's pore size must be optimized. The optimal concentrations of the enzyme (urease) and antibody were determined at the maximum absorbance change, that is, the maximum pH change. The pH change was measured using a field-effect transistor (FET). The correlation between pH change and threshold voltage was estimated to be 21.7 mV/pH, and the correlation between pH change and the source-drain current was estimated to be -379 nA/pH. For the one-step immunoassay, antibodies against target bacteria were isolated from horse serum by filtration, and these antibodies were estimated to have a sufficiently high specificity to overcome cross-reactivity among five types of food poisoning-related bacteria: Escherichia coli O157, Salmonella typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. Finally, the FET-based one-step immunoassay was demonstrated for five types of food poisoning-related bacteria in human serum.


Assuntos
Microbiologia de Alimentos , Doenças Transmitidas por Alimentos , Humanos , Imunoensaio , Salmonella typhimurium , Bactérias , Doenças Transmitidas por Alimentos/diagnóstico , Anticorpos , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise
18.
Talanta ; 255: 124197, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36571974

RESUMO

Bacterial reference materials (RMs) play a crucial role in many analytical processes of microbiological detection. Currently, bacteria are typically counted using the traditional plate-based approach, which results in a higher uncertainty of bacterial RMs unfortunately. Therefore, novel methods are urgently required for the value assignment of RMs in the field of microbiology to derive measurement traceability and accuracy. A potential primary method for microbiological quantification based on flow cytometry (FCM) is described in this study using Escherichia coli O157 (E. coli O157) as an example. The proposed method was applied to determine the number of viable E. coli O157 cells in the RMs with a result of (5.48 ± 0.27) × 108 cells mL-1, which was in good agreement with the result obtained using the plate-based method (En = 0.47). Additionally, this method could be entirely described and understood by equations, and provides formal traceability to the SI for counts of viable bacterial cells, while the associated relative expanded uncertainty (4.93%, k = 2) was significantly lower in comparison to the plate-based method. Therefore, the FCM-based method might be a potential primary method for characterizing bacterial RMs. To our knowledge, this is the first description of FCM as a potential primary method for accurate and traceable quantification of viable bacterial cells with a comprehensive uncertainty statement in microbiological metrology.


Assuntos
Escherichia coli O157 , Microbiologia de Alimentos , Citometria de Fluxo/métodos , Bactérias
19.
Food Chem ; 409: 135296, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-36586253

RESUMO

A novel sandwich assay for the detection of L. monocytogenes was designed based on antibiotic magnetic separation and enzymatic colorimetry. PEG-mediated cefepime functionalized magnetic nanoparticles (Cefe-PEG-MNPs) was reported for the first time to anchor L. monocytogenes cells with excellent bacterial capture capacity. The capture efficiency of L. monocytogenes in lettuce sample with high concentration (3.1 × 106 CFU/mL) was more than 73.8%. Anti-L. monocytogenes monoclonal antibody was adopted as the second anchoring agent to ensure the specificity for L. monocytogenes, which was co-modified with HRP on the surface of gold nanoparticles (AuNPs-HRP/mAb) to form AuNPs-HRP/mAb@L. monocytogenes@Cefe-PEG-MNPs sandwich complexes, and TMB was added to generate a colorimetric signal. The limit of detection in contaminated lettuce, watermelon juice, and fresh meat samples were both 3.1 × 102 CFU/mL, and the whole assay takes about 110 min. Based on the above facts, the proposed method has great potential for rapid separation and detection of pathogenic bacteria in food.


Assuntos
Listeria monocytogenes , Nanopartículas de Magnetita , Ouro , Colorimetria/métodos , Alface/microbiologia , Cefepima , Microbiologia de Alimentos
20.
Meat Sci ; 197: 109065, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36481517

RESUMO

This study investigated the antimicrobial and antibiofilm efficacy of separate and combined treatments of Lactobacillus curvatus B67-produced postbiotic and the polyphenolic flavanol quercetin against Listeria monocytogenes and Salmonella enterica ser. Typhimurium. The antimicrobial potentiality of the postbiotic was chiefly associated with organic acids (e.g., lactic and acetic acids). At sub-minimum inhibitory concentration (1/2 MIC), the postbiotic and quercetin effectively reduced the pathogenic biofilm cells on processed pork sausage and meat-processing surfaces (e.g., stainless-steel and rubber). Moreover, the postbiotic exhibited strong residual antimicrobial efficacy over diverse pH and temperature ranges. In addition, the combination of postbiotic with quercetin increased the leakage of pathogenic intracellular metabolites (e.g., nucleic acids and protein) and inhibited pathogenic biofilm formation on both biotic and abiotic surfaces. Therefore, this study confirmed that lactic acid bacteria-derived postbiotic and plant-derived quercetin could be used as potential alternative bioprotective agents in the meat processing industry.


Assuntos
Listeria monocytogenes , Salmonella enterica , Lactobacillus , Quercetina/farmacologia , Conservação de Alimentos , Carne , Microbiologia de Alimentos
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