Staphylococcus aureus is one of the main aetiological agents causing food‐borne diseases. Some strains produce enterotoxins responsible for food poisoning. In addition, they can form biofilms on ...several surfaces such as plastics, glass and stainless steel making it difficult to eliminate them. The present study evaluated, for the first time, the antibacterial and antibiofilm activities of the synthetic compound LMM6 against S. aureus. The minimum inhibitory concentration was 0·97, 1·95 and 1·95 μg ml−1 against S. aureus ATCC 25923, S. aureus 629/94 and S. aureus FRI S‐6, respectively. The time‐kill curves showed that 96 h treatment with LMM6 reduced approximately 4 log CFU per ml at all tested concentrations. Furthermore, LMM6 reduced S. aureus preformed biofilm by approximately 1 log CFU per cm2. During biofilm formation, a reduction of approximately 4 log CFU per cm2 was observed. LMM6 also reduced biofilm biomass during (~60%) and after biofilm formation (~25 to 45%), as shown by the crystal violet assay. Based on these results, we conclude that LMM6 exhibits antibacterial and antibiofilm activity and may be an innovative synthetic molecule for controlling S. aureus.
Significance and Impact of the Study: Staphylococcus aureus is an important causative agent of food poisoning. In search for new control alternatives, this study demonstrated that the synthetic compound LMM6 inhibits S. aureus growth and biofilm formation. To our knowledge, this is the first report describing the antimicrobial and antibiofilm activity of LMM6 1,3,4‐oxadiazole derivatives against S. aureus strains.
Abstract The aim of this study was to develop a lasagna pasta enriched with dried mix of tuna (30%) and tilapia (70%) and formulate ready lasagna with enriched pasta. Lasagna pasta was elaborated ...with increasing levels (0, 5, 10 and 15%) of dried mix. Moisture, lipids and calories were not different between the inclusion levels; crude protein and ash increased linearly, carbohydrates reduced linearly, according to increasing levels of inclusion. There was an increase in n-3 and n-6 fatty acids with the inclusion of mix in lasagna. Between lasagna prepared with different sauces (tuna, chicken and bolognese), and pasta with 15% mix, it was observed that tuna lasagna had lower moisture content and higher protein, lipids, ash, carbohydrates and calories. All lasagna showed optimal sensory acceptance, indicating that the inclusion of 15% dried mix of tilapia and tuna in the pasta is feasible to improve the nutritional composition of lasagna.
The effects of high-pressure processing (HPP; 300, 400, 500 and 600 MPa for 5 min) compared to Holder pasteurization treatments on the macronutrients, acidity in Dornic, total coliforms, fatty acids ...(FA) composition, and the triacylglycerols (TAG) profile of mature human milk (HM) were evaluated. The results showed that both processes eliminated the microorganisms present, and the concentration of macronutrients and Dornic acidity did not show significant differences in processes. A total of 34 FAs were identified by gas chromatography with flame ionization detector, with palmitic and oleic acids having the highest concentrations. Regarding the TAG profile determined by direct infusion by electrospray ionization mass spectrometry, TAG PLO (P: palmitic acid; L: linoleic acid; and O: oleic acid) was the one with the highest estimated concentration (6.52–7.27%). The evaluation of hierarchical clustering analysis results suggests that processing with lower pressures was more beneficial for HM due to the similarity between the intensities of the TAGs identified in each sample and the control HM sample. Besides, the results obtained on the evaluated components suggested that HPP could be a promising alternative to HoP applied in human milk banks since it maintained the characteristics of HM and is faster than HoP.
•High-pressure processing may be considered an alternative to Holder pasteurization.•HPP with lower pressures showed greater similarity with the control HM sample.•All evaluated HPP eliminated the microorganisms of the coliform group.•Oleic, palmitic and linoleic acids showed higher concentrations in HM samples.
The present study deals with dehydrated mixture of salmon (20%) and tilapia (80%) at 0, 5, 10 and 15% inclusion levels in spinach cake, and evaluates its proximate composition, sensory and ...microbiological characteristics. It was included 0, 5, 10 and 15% of the dehydrated mixture in the dough of the cake. Moisture and lipid contents were not modified (p >0.05) when the mixture was included in the cake. There was a positive linear effect for crude protein (y=6.24 + 0.29x, R²=0.77) and mineral (y=0.60 + 0.19x, R²=0.85). Carbohydrate and calorie contents decreased linearly (p <0.01) according to increasing levels of the mixture in the cake. With regard to sensory analysis, there was a negative linear effect for taste (y=7.48 - 0.07x, R2=0.98), texture (y=7.48 - 0.047x, R2=0.93), acceptance (y=7.13 - 0.046x, R2=0.99) and purchase intention (y=3.82 - 0.039x, R2=0.93), demonstrating that increasing levels of inclusion of the dehydrated mixture caused a decrease in the acceptance of the cake. It can be concluded that the inclusion of up to 15% of salmon and tilapia dehydrated mixture in spinach cake increases the contents of crude protein and mineral matter, and reduces the carbohydrate content and calorie. However, based on the sensory results, it is recommended to include 10% of the dehydrated mixture of fish in the spinach cake.
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•Gold nanoparticles with a small diameter are synthesized and stabilized by copolymer P-123 by the solid dispersion method.•The fluorescence emission studies presented wavelength ...dependence, suggesting the feasibility of image-guided diagnostics.•Confirmed generation of singlet oxygen by samples synthesized through studies with the ABDA probe.•The higher percentage of P-123 improves the inhibitory effect when combining PDT with PTT for an antifungal effect.
The search for more effective drugs and therapies for the treatment of microbial diseases has driven the development of nanomedicine in recent years. In this sense, the present work shows the combination of photodynamic therapy (PDT) and photothermal therapy (PTT) using the photoactive drugs: methylene blue (MB) and gold nanoparticles (AuNPs). The ABA triblock Pluronic® P-123 copolymer was employed both as a micellar nanocarrier and reductant/stabilizing agent for AuNPs. The synthesis of gold nanoparticles (AuNPs) was carried out in situ through the redox process of AuCl3 gold salt in the presence of different concentrations of P-123 ranging from 0.25 % to 8.00 % ( % w/V) following the solid dispersion method. The MB was incorporated into the copolymeric micellar system by passive and active incorporation methods. In general, the system containing 1.00 % and 2.00 % (w/V) of P-123 was the more efficient and reproducible to obtain P-123/AuNPs/MB samples. The AuNPs synthesized presented plasmonic resonance peaks ranging from 535 to 554 nm, characteristic of spherical AuNPs. Dynamic Light Scattering and transmission electronic microscopy confirm the structure of the polymeric micelle around 20 nm and the AuNPs 3 nm diameters. The fluorescence emission showed to be dependent on the excitation wavelength, a promising feature for biological applications, especially when considering an image-guided diagnosis. Furthermore, the Stern-Volmer study by fluorescence quenching with iodide showed that active incorporation favors greater internalization of MB at the hydrophobic core of the micelle. On the other hand, the passive incorporation method placed MB in the most hydrophilic region in the micelle. The photodynamic effect was confirmed by singlet oxygen generation using ABDA as a probe. Thermal Lens spectroscopy and heating studies also confirms the heat generation by the system. In addition, the results point to synergism both in the generation of 1O2 and heat. The in vitro susceptibility of the samples was evaluated in Candida albicans strain. Better antifungal activity was observed in the sample of 2.00 % P-123/AuNPs/MB by Passive incorporation, illuminated with red and green LEDs. The biological study in bacteria strains of E. coli and S. aureus has shown that both percentages of P-123 with MB and AuNPs/MB by passive incorporation were efficient in controlling the evaluated bacteria. In this way, the present work showed promise for the treatment of antimicrobials through the combined therapy of PDT and PTT.
Staphylococcus aureus is one of the main etiological agents causing foodborne diseases, and the development of new antibacterial agents is urgent. This study evaluated the antibacterial activity and ...the possible mechanism of action of the 1,3,4-oxadiazole LMM6 against S. aureus. The minimum inhibitory concentration (MIC) of LMM6 ranged from 1.95 to 7.81 µg ml-1. The time-kill assay showed that 48-h treatment at 1× to 8× MIC reduced S. aureus by 4 log colony forming unit (CFU), indicating a bacteriostatic effect. Regarding the possible mechanism of action of LMM6, there was accumulation of reactive oxygen species (ROS) and an increase in the absorption of crystal violet (∼50%) by the cells treated with LMM6 at 1× and 2× MIC for 6-12 h. In addition, there was increased propidium iodide uptake (∼84%) after exposure to LMM6 for 12 h at 2× MIC. After 48 h of treatment, 100% of bacteria had been injured. Scanning electron microscopy observations demonstrated that LMM6-treated cells were smaller compared with the untreated group. LMM6 exhibited bacteriostatic activity and its mechanism of action involves increase of intracellular ROS and disturbance of the cell membrane, which can be considered a key target for controlling the growth of S. aureus.
This study evaluated the antibacterial activity of cinnamaldehyde (CIN) and biogenic silver nanoparticles (BioAgNP), alone and in combination, against
Escherichia coli
,
Salmonella
Typhimurium, and
...Staphylococcus aureus
in vitro. Their sanitation activities on fresh sweet grape tomatoes were also evaluated. CIN and BioAgNP inhibited the growth of the tested bacteria, and at low concentrations, their combinations presented a synergistic effect. In the sanitization of fresh sweet grape tomatoes, CIN (156 µg/mL) combined with BioAgNP (31.25 µM) at subinhibitory concentrations inhibited the growth of
E. coli
after only 5 min of contact. Exposed samples showed no growth of
E. coli
during their shelf life. The combination of these compounds did not change significantly (
p
> 0.05) the physicochemical properties of sweet grape tomatoes and showed that CIN combined with BioAgNP could represent an effective method for decontaminating fruits and vegetables. This combination has great potential for application in the prevention of foodborne diseases.
Stryphnodendron adstringens
is a medicinal plant that has a broad spectrum of action, including antibacterial activity. The aim of the present study was to evaluate the effect of
S. adstringens
alone ...and in combination with potassium sorbate (PS) against foodborne bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined and, for most of the bacteria tested, the crude extract (CE)
,
aqueous fraction (AQF), and ethyl-acetate fraction (EAF) of
S. adstringens
had a MIC and MBC ranging from 500 to ≥ 1000 µg/mL. The AQF and EAF showed greater activity against
S. aureus
strains (MIC = 125 to 250 µg/mL; MBC = 500 to 1000 µg/m). Quantitative cell viability was determined and was observed reductions ranging from 3.0 to 5.8 log10 CFU/ml.The combination of
S. adstringens
and PS against seven
S. aureus
isolates was determined by the checkerboard method at neutral and acid pH. In a neutral medium, the AQF + PS combination presented synergistic or additive interactions against six
S. aureus
strains. The combination of EAF + PS resulted in additive interactions against four bacterial isolates. In an acidic medium, the AQF + PS combination was synergistic or additive against all
S. aureus
, while EAF + PS presented the same effect against six
S. aureus
strains
S. adstringens
showed important antibacterial effects against foodborne
S. aureus
strains. Moreover, the combination of
S. adstringens
fractions and PS improved the antibacterial activity compared to the compounds utilized individually. The combined use of these compounds may be an alternative to reduce bacterial food contamination and improve food safety.
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