Search Results (64)

In this study, the degradation of Nile Blue dye was investigated using homogeneous and heterogeneous photocatalytic methods based on the photo-Fenton reaction. More specifically, for homogeneous photocatalysis, the classical photo-Fenton (UV/Fe²⁺/H₂O₂) and modified photo-Fenton-like (UV/Fe²⁺/S₂O₈²⁻) systems were studied, while for heterogeneous photocatalysis, a commercial MOF catalyst, Basolite F300, and a natural ferrous mineral, geothite, were employed. Various parameters—including the concentrations of the oxidant and catalyst, UV radiation, and pH—were investigated to determine their influence on the reaction rate. In homogeneous systems, an increase in iron concentration led to an enhanced degradation rate of the target compound. Similarly, increasing the oxidant concentration accelerated the reaction rate up to an optimal level, beyond which radical scavenging effects were observed, reducing the overall efficiency. In contrast, heterogeneous systems exhibited negligible degradation in the absence of an oxidant; however, the addition of oxidants significantly improved the process efficiency. Among the tested processes, homogeneous techniques demonstrated a superior efficiency, with the conventional photo-Fenton process achieving complete mineralization within three hours. Kinetic analysis revealed pseudo-first-order behavior, with rate constants ranging from 0.012 to 0.688 min⁻¹ and correlation coefficients (R²) consistently above 0.90, confirming the reliability of the applied model under various experimental conditions. Nevertheless, heterogeneous techniques, despite their lower degradation rates, also achieved high removal efficiencies while offering the advantage of operating at a neutral pH without the need for acidification. Full article

Sichuan paocai, a microbial food predominantly fermented by lactic acid bacteria and hosting a complex and diverse microbial ecosystem, serves as an ideal habitat for bacteriophages. However, relatively few studies have been conducted on isolating bacteriophages from fermented vegetables and their application in vegetable fermentation. In this study, three staphylococcal bacteriophages, ΦSx-2, ΦSs-1, and ΦSs-2, were isolated and purified from Sichuan paocai using the spot test method. The morphological features of the phages were characterized using transmission electron microscopy (TEM), while key biological properties such as one-step growth kinetics were systematically evaluated, ultimately verifying their taxonomic placement within the Caudoviricetes class. Furthermore, the potential effects of these phages on the microbial community structure and physicochemical properties during paocai fermentation were investigated using high-throughput sequencing and standard physicochemical assays. Microbial community analysis demonstrated that introducing the phages significantly increased the relative abundance of lactic acid bacteria while reducing the prevalence of spoilage bacteria such as Erwinia, Pantoea, and Enterobacter. Physicochemical assessments revealed that adding phages accelerated the acidification process of paocai, effectively reduced nitrite levels, and increased the concentrations of lactic and acetic acids. Additionally, notable differences in color and flavor were observed between the two groups of paocai during the fermentation process. In summary, the inoculation of bacteriophages ΦSx-2, ΦSs-1, and ΦSs-2 optimized the microbial community structure, enhanced the fermentation process, and improved the quality of Sichuan paocai. Full article

Yogurt is a highly consumed dairy product valued for its nutritional and probiotic properties. Its production involves the use of lactic acid bacteria, which drive biochemical transformations during fermentation. Optimizing fermentation time without compromising yogurt quality is essential for improving processing efficiency. Pulsed electric fields (PEFs) constitute a promising technology that stimulates microbial activity. In this study, a yogurt starter inoculum suspended in milk (IM) with different fat content (0.5–2.8%) was treated with low-intensity PEFs (1 kV/cm, 800–1600 µs) to enhance fermentation kinetics. pH, soluble solids, lactose, lactic acid, and riboflavin concentrations were monitored during 6 h, comparing PEF-treated IM (PEF-IM) and untreated IM (C-IM). PEF-treatments applied to IM reduced the fermentation time of inoculated milk by 4.3–20.4 min compared to C-IM. The lowest fermentation time (5.1 ± 0.16 h) was observed in milk added with PEF-IM (2.8% fat) treated at 1 kV/cm for 1600 µs. Milk inoculated with PEF-IM exhibited enhanced lactose consumption (1.6–3.1%) and higher lactic acid production (7.2%) than milk with C-IM. Riboflavin concentration (0.9–7%) decreased between 2 and 4 h, but it stabilized at the end of fermentation. Obtained results suggest that PEFs promote reversible electroporation in microbial cells, facilitating nutrient uptake and acidification, making it a promising assisted-fermentation approach to improve yogurt production. Full article

Lachancea thermotolerans help increase the acidity of wines by producing L-lactic acid, which can serve as a strategy to mitigate the decrease in total acidity in wines promoted by climate change. The aim of the present paper is to test the capability of wine bioacidification of wild strains isolated from Rioja AOC. For this purpose, L. thermotolerans strains isolated from musts were used in mixed fermentation (co-inoculation and sequential inoculation) with Saccharomyces cerevisiae to determine the fermentation performance and L-lactic acid production, in both laboratory scale and pilot scale. Fermentation kinetics was evaluated, in addition to the final wine chemical composition and organoleptical properties. The results indicated that the isolated strains produced L-lactic acid; these effects were dependent on the strain and the inoculation strategy, being higher the effect in sequential inoculation (9.20 g/L) than in co-inoculation. This L-lactic acid production capacity was maintained at a pilot scale (4.65 g/L), in which the acidity increase was perceptible in the sensorial analysis, and an ethanol concentration decrease was also reported. The wine acidification depends on the appropriate selection of the strains, the inoculation procedure, the yeast adaptation to media, and competence with other yeast species present in the fermentation broth. The wild L. thermotolerans Lt97 strain could be used as a bioacidification tool for wines affected by climate change. Full article

It is well established that certain carboxylic acid compounds can effectively inhibit tyrosinase activity. This study investigated the mechanisms by which four carboxylic acid compounds—3-phenyllactic acid, lactic acid, L-pyroglutamic acid, and malic acid—inhibit tyrosinase and melanogenesis. IC₅₀ values for mushroom tyrosinase inhibition ranged from 3.38 to 5.42 mM, with 3-phenyllactic acid (3.50 mM), lactic acid (5.42 mM), and malic acid (3.91 mM) exhibiting mixed-type inhibition, while L-pyroglutamic acid (3.38 mM) showed competitive inhibition, as determined by enzymatic kinetic analysis. Additionally, the acidification effects of lactic acid, L-pyroglutamic acid, and malic acid contributed to the reduction in tyrosinase activity. Furthermore, all four carboxylic acid compounds effectively inhibited DOPA auto-oxidation (IC₅₀ = 0.38–0.66 mM), ranking in potency as follows: malic acid (0.38 mM) > lactic acid (0.57 mM) > 3-phenyllactic acid (0.63 mM) > L-pyroglutamic acid (0.66 mM). These compounds also demonstrated a dose-dependent reduction in melanin production in B16-F10 cells. Proteomic analysis further revealed that these compounds not only inhibit key proteins involved in melanin synthesis, such as tyrosinase, tyrosinase-related protein 1, and tyrosinase-related protein 2, but also potentially modulate other genes associated with melanogenesis and metabolism, including Pmel, Slc45a2, Ctns, Oca2, and Bace2. Network toxicology analysis indicated that these four compounds exhibit a low risk of inducing dermatitis. These findings suggest that these compounds may indirectly regulate melanin-related pathways through multiple mechanisms, highlighting their potential for further applications in cosmetics and pharmaceuticals. Full article

To achieve the required recycling rates, organic recycling via composting should be widely introduced in Poland for selectively collected biowaste. However, this process not only produces compost but also leachate (L_CB), a nitrogen- and organics-rich liquid by-product. So far there has been limited information on the application of anaerobic digestion (AD) for treating L_CB, which has fermentative potential. However, for effective methane production (MP) via AD, the ratio of chemical oxygen demand to total Kjeldahl nitrogen (COD/TKN) and pH of L_CB are too low; thus, it should be co-digested with other organics-rich waste, e.g., glycerine (G). The present study tested the effect of G content in feedstock (in the range of 3–5% (v/v)) on the effectiveness of co-digestion with L_CB, based on MP and the removal of COD. MP was accessed by using an automatic methane potential test system (AMPTS). Regardless of the feedstock composition (L_CB, or L_CB with G), the efficiency of COD removal was over 91%. Co-digestion not only increased MP by 6–15%, but also the methane content in the biogas by 4–14% compared to L_CB only (353 NL/kg COD_added, 55%). MP and COD removal proceeded in two phases. During co-digestion in the 1st phase, volatile fatty acids (VFA) accumulated up to 2800 mg/L and the pH decreased below 6.8. The presence of G altered the shares of individual VFA and promoted the accumulation of propionic acid in contrast to L_CB only, where caproic acid predominated. An initial accumulation of propionic acid and acidification in the mixtures decreased the kinetic constants of MP (from 0.79 to 0.54 d⁻¹) and the rate of COD removal (from 2193 to 1603 mg/(L·d)). In the 2nd phase, the pH recovered, VFA concentrations decreased, and MP was no longer limited by these factors. However, it should be noted that excessive amounts of G, especially in reactors with constant feeding, may cause VFA accumulation to a greater extent and create a toxic environment for methanogens, inhibiting biogas production. In contrast, digestion of L_CB only may lead to ammonium buildup if the COD/TKN ratio of the feedstock is too low. Despite these limitations, the use of AD in the treatment of L_CB as a sustainable “closed-loop nutrient” technology closes the loop in composting of biowaste. Full article

The phenomenon of pore blockage caused by injected suspended particles significantly impacts the efficiency of water injection and production capacity release in offshore oilfields, leading to increased additional resistance during the injection process. To enhance water injection volumes in injection wells, it is essential to quantitatively study the additional resistance caused by suspended particle blockage during water injection. However, there is currently no model for calculating the additional resistance resulting from suspended particle blockage. Therefore, this study establishes a permeability decline model based on the microscopic dispersion kinetic equation of particle transport. The degree of blockage is characterized by the reduction in fluid volume, and the additional resistance caused by particle migration and blockage during water injection is quantified based on the fluid volume decline. This study reveals that over time, suspended particles do not continuously migrate deeper into the formation but tend to deposit near the wellbore, blocking pores and increasing additional resistance. Over time, the concentration of suspended particles near the wellbore approaches the initial concentration of the injected water. An increase in seepage velocity raises the peak concentration of suspended particles, but when the seepage velocity reaches a certain threshold, its effect on particle migration stabilizes. The blockage location of suspended particles near the wellbore is significantly influenced by seepage velocity and time. An increase in particle concentration and size accelerates blockage formation but does not change the blockage location. As injection time increases, the fitted injection volume and permeability exhibit a power-law decline. Based on the trend of injection volume reduction, the additional resistance caused by water injection is calculated to range between 0 and 3.85 MPa. Engineering cases indicate that blockages are challenging to remove after acidification, and the reduction in additional resistance is limited. This study provides a quantitative basis for understanding blockage patterns during water injection, helps predict changes in additional resistance, and offers a theoretical foundation for targeted treatment measures. Full article

The use of starter cultures in the meat industry is common, even if the number of available commercial cultures is limited, inducing product standardisation and microbial diversity reduction. On the other hand, some artisanal products relying on spontaneous fermentation can represent a source of isolation of new interesting strains. In this work, four LAB strains derived from Mediterranean spontaneously fermented sausages were tested as new starter cultures for the industrial production of fermented sausages, in comparison to a commercial starter culture. The products obtained were analysed for physico-chemical parameters, microbiota, biogenic amines and aroma profile. A consumer test was also performed to evaluate product acceptability. The strains induced different acidification kinetics. LAB counts showed high persistence when Latilactobacillus curvatus HNS55 was used as the starter culture, while the addition of Companilactobacillus alimentarius CB22 resulted in a high concentration of enterococci (6 log CFU/g), 2 log higher than in other samples. Tyramine was detected at concentrations of 150–200 mg/kg, except for in the sample produced with Lactiplantibacillus plantarum BPF2 (60 mg/kg). Differences were observed in the aroma profile, with a high amount of 2-butanone found in the samples obtained with Comp. alimentarius CB22. These latter sausages also showed the lowest score in terms of acceptability. This study allowed us to select new LAB strains for fermented sausage starter cultures, increasing the product diversification. Full article

Tomato waste, characterized by high organic matter and moisture content, offers a promising substrate for anaerobic digestion, though rapid acidification can inhibit methanogenic activity. This study investigated the performance of a 10.25 L anaerobic fixed biofilm reactor for biogas production using liquid tomato waste, processed through grinding and filtration, at high organic loading rates, without external pH control or co-digestion. Four scouring pads were vertically installed as a fixed bed within a fiberglass structure. Reactor performance and buffering capacity were assessed over three stages with progressively increasing organic loading rates (3.2, 4.35, and 6.26 gCOD/L·d). Methane yields of 0.419 LCH4/gCOD and 0.563 LCH4/g VS were achieved during the kinetic study following stabilization. Biogas production rates reached 1586 mL/h, 1804 mL/h, and 4117 mL/h across the three stages, with methane contents of 69%, 65%, and 72.3%, respectively. Partial alkalinity fluctuated, starting above 1500 mg CaCO₃/L in Stage 1, dropping below 500 mg CaCO₃/L in Stage 2, and surpassing 3000 mg CaCO₃/L in Stage 3. Despite periods of forced acidification, the system demonstrated significant resilience and high buffering capacity, maintaining stability through hydraulic retention time adjustments without the need for external pH regulation. The key stability indicators identified include partial alkalinity, effluent chemical oxygen demand, pH, and one-day cumulative biogas. This study highlights the effectiveness of anaerobic fixed biofilm reactors in treating tomato waste and similar fruit and vegetable residues for sustainable biogas production. Full article

The aim of the present study was to evaluate the characteristics of carcasses, monitor their pH evolution during the first 24 h post-mortem, and determine the time required for the establishment and resolution of rigor mortis in different categories of Botucatu rabbits. Live weight at slaughter, carcass weight, and yield were higher in 12-month-old animals compared to 3-month-old rabbits, regardless of sex. There was an effect of muscle type, age, and sex on the kinetics of muscle acidification, with the Biceps femoris showing a significantly higher pH than the Longissimus lumborum from 4 h post-mortem onward. The establishment of rigor mortis occurred at 5 h post-mortem in young rabbits and bucks and at 6 h post-mortem in does, along with pH stabilization, while the resolution of rigor occurred at 18 h post-mortem for all types of carcasses evaluated. In conclusion, Botucatu rabbit carcasses should be chilled continuously at 4 °C for a minimum of 18 h to ensure efficient rigor mortis progression and muscle-to-meat transformation throughout the carcass. Full article

The efficiency of virus internalization into target cells is a major determinant of infectivity. SARS-CoV-2 internalization occurs via S-protein-mediated cell binding followed either by direct fusion with the plasma membrane or endocytosis and subsequent fusion with the endosomal membrane. Despite the crucial role of virus internalization, the precise kinetics of the processes involved remains elusive. We developed a pipeline, which combines live-cell microscopy and advanced image analysis, for measuring the rates of multiple internalization-associated molecular events of single SARS-CoV-2-virus-like particles (VLPs), including endosome ingression and pH change. Our live-cell imaging experiments demonstrate that only a few minutes after binding to the plasma membrane, VLPs ingress into RAP5-negative endosomes via dynamin-dependent scission. Less than two minutes later, VLP speed increases in parallel with a pH drop below 5, yet these two events are not interrelated. By co-imaging fluorescently labeled nucleocapsid proteins, we show that nucleocapsid release occurs with similar kinetics to VLP acidification. Neither Omicron mutations nor abrogation of the S protein polybasic cleavage site affected the rate of VLP internalization, indicating that they do not confer any significant advantages or disadvantages during this process. Finally, we observe that VLP internalization occurs two to three times faster in VeroE6 than in A549 cells, which may contribute to the greater susceptibility of the former cell line to SARS-CoV-2 infection. Taken together, our precise measurements of the kinetics of VLP internalization-associated processes shed light on their contribution to the effectiveness of SARS-CoV-2 propagation in cells. Full article

This study synthesized and modified a semi-interpenetrating polymer network hydrogel from polyacrylamide, N,N′-dimethylacrylamide, and maleic acid in a potassium hydroxide solution. The chemical composition, interior morphology, thermal properties, mechanical characteristics, and swelling behaviors of the initial hydrogel (SH) and modified hydrogel (SB) in water, salt solutions, and buffer solutions were investigated. Hydrogels were used as phosphate fertilizer (PF) carriers and applied in farming techniques by evaluating their impact on soil properties and the growth of mustard greens. Fourier-transform infrared spectra confirmed the chemical composition of SH, SB, and PF-adsorbed hydrogels. Scanning electron microscopy images revealed that modification increased the largest pore size from 817 to 1513 µm for SH and SB hydrogels, respectively. After modification, the hydrogels had positive changes in the swelling ratio, swelling kinetics, thermal properties, mechanical and rheological properties, PF absorption, and PF release. The modification also increased the maximum amount of PF loaded into the hydrogel from 710.8 mg/g to 770.9 mg/g, while the maximum % release of PF slightly increased from 84.42% to 85.80%. In addition, to evaluate the PF release mechanism and the factors that influence this process, four kinetic models were applied to confirm the best-fit model, which included zero-order, first-order, Higuchi, and Korsmeyer–Peppas. In addition, after six cycles of absorption and release in the soil, the hydrogels retained their original shapes, causing no alkalinization or acidification. At the same time, the moisture content was higher as SB was used. Finally, modifying the hydrogel increased the mustard greens’ lifespan from 20 to 32 days. These results showed the potential applications of modified semi–IPN hydrogel materials in cultivation. Full article

Water contamination with various micropollutants is a serious environmental concern since this group of chemicals cannot always be removed efficiently with advanced treatment methods. Therefore, alternative chemical- and energy-intensive oxidation processes have been proposed for the removal of refractory and/or toxic chemicals. However, similar treatment performances might result in different environmental impacts. Environmental impacts can be determined by adopting a life cycle assessment methodology. In this context, lab-scale experimental data related to 100% iprodione (a hydantoin fungicide/nematicide selected as the model micropollutant at a concentration of 2 mg/L) removal from simulated tertiary treated urban wastewater (dissolved organic carbon content = 10 mg/L) with UV-C-activated persulfate treatment were studied in terms of environmental impacts generated during photochemical treatment through the application of a life cycle assessment procedure. Standard guidelines were followed in this procedure. Iprodione removal was achieved at varying persulfate concentrations and UV-C doses; however, an “optimum” treatment condition (0.03 mM persulfate, 0.5 W/L UV-C) was experimentally established for kinetically acceptable, 100% iprodione removal in distilled water and adopted to treat iprodione in simulated tertiary treated wastewater (total dissolved organic carbon of iprodione + tertiary wastewater = 11.2 mg/L). The study findings indicated that energy input was the major contributor to all the environmental impact categories, namely global warming, abiotic depletion (fossil and elements), acidification, eutrophication, freshwater aquatic ecotoxicity, human toxicity, ozone depletion, photochemical ozone creation, and terrestrial ecotoxicity potentials. According to the life cycle assessment results, a concentration of 21.42 mg/L persulfate and an electrical energy input of 1.787 kWh/m³ (Wh/L) UV-C light yielded the lowest undesired environmental impacts among the examined photochemical treatment conditions. Full article

The aim of this study was to assess the impact of production parameters on the reproducibility of kombucha fermentation over several production cycles based on backslopping. Six conditions with varying oxygen accessibility (specific interface surface) and initial acidity (through the inoculation rate) of the cultures were carried out and compared to an original kombucha consortium and a synthetic consortium assembled from yeasts and bacteria isolated from the original culture. Output parameters monitored were microbial populations, biofilm weight, key physico-chemical parameters and metabolites. Results highlighted the existence of phases in microbial dynamics as backslopping cycles progressed. The transitions between phases occurred faster for the synthetic consortium compared to the original kombucha. This led to microbial dynamics and fermentative kinetics that were reproducible over several cycles but that could also deviate and shift abruptly to different behaviors. These changes were mainly induced by an increase in the Saccharomyces cerevisiae population, associated with an intensification of sucrose hydrolysis, sugar consumption and an increase in ethanol content, without any significant acceleration in the rate of acidification. The study suggests that the reproducibility of kombucha fermentations relies on high biodiversity to slow down the modulations of microbial dynamics induced by the sustained rhythm of backslopping cycles. Full article

In this paper, the local corrosion inhibition effect of imidazoline on N80 oil pipeline steel in a NaCl-Na₂S solution was studied by the simulated blocking tank cell method, and the corrosion processes of the cathode and anode in the blocking zone were simulated. The blocking corrosion behavior of the pipeline tubing steel N80 in simulated corrosion solutions without and with different concentrations of an imidazoline corrosion inhibitor was studied by chemical analysis and electrochemical analysis. The results show that in the three solution systems, after the anode polarization of the occluded cell, the solution in the occluded region is acidified, the pH value decreases sharply, the migration of Cl⁻ and S²⁻ increases, and the concentration is increased in the blocked area. After adding the imidazoline corrosion inhibitor, the imidazoline inhibitor can reduce the migration of small-radius anions (Cl⁻ and S²⁻) to the occluded area, inhibit the acidification of the solution in the occluded area, and prevent the dissolution of metals in the occluded area. As a result, the corrosion of the occluded area is slowed down due to the change in the chemical and electrochemical state of the occluded area. In the three corrosion solution systems of 2% Na₂S + 5% NaCl, 2% Na₂S + 8% NaCl, and 2% Na₂S + 10% NaCl, the imidazoline corrosion inhibitor can form an adsorption film on the metal surface, thereby increasing the polarization resistance and decreasing the corrosion rate. The addition of an imidazoline corrosion inhibitor can significantly increase the kinetic constant of anode polarization, which can effectively inhibit the local corrosion of N80 steel in these corrosion systems. Full article