Search Results (1,025)

Mychonastes homosphaera MHSC24 is a green microalga newly isolated from a brackish coastal site in Korea. This study represents the first indigenous record of this species in the country. It provides a comprehensive characterization of its morphological, molecular, physiological, and biochemical characteristics. This microalga was identified through morphological observations and multilocus phylogenetic analyses. Strain MHSC24 exhibited robust growth under mesophilic temperatures (15–27 °C), moderate light intensities (88–300 μmol photons m⁻² s⁻¹), and low salinity levels (0–10 PSU). Optimal growth was observed at 27 °C, 193 μmol photons m⁻² s⁻¹, and 0 PSU. Under standard cultivation, the strain exhibited high protein levels (~54% of dry weight, DW) and accumulated substantial amounts of canthaxanthin (5.59 mg g⁻¹ DW), the predominant carotenoid in its pigment profile. Thus, MHSC24 is a promising candidate for sustainable protein- and carotenoid-based applications. Palmitic acid (11.95 mg g⁻¹ DW) and galactose (2.07 mg g⁻¹ DW) were the predominant fatty acid and monosaccharide, respectively. The physiological resilience, high protein yield, and substantial canthaxanthin accumulation of MHSC24 support its potential utilization in the functional food, feed, and nutraceutical sectors. Therefore, this study provides a basis for optimized cultivation strategies and industrial exploitation of indigenous Korean microalgae. Full article

This study aimed to evaluate the effect of seasonal dynamics of phytoplankton biomass in the Bay of Gdansk (Southern Baltic Sea, Poland) on its usability for anaerobic digestion. Biomass samples were collected between May and October (2023–2024) for quantitative, taxonomic, and chemical analyses as well as for anaerobic digestion in mesophilic periodical bioreactors. Study results demonstrated substantial seasonal variations in the taxonomic composition of phytoplankton, with green algae and dinoflagellates prevailing in the spring, cyanobacteria in the summer, and diatoms in the autumn. These fluctuations were also reflected in the chemical composition of the biomass and its anaerobic digestion efficiency. The highest methane yield of 270 ± 13 mL CH₄/g VS and its highest production rate reaching 32.5 ± 1.6 mL CH₄/g VS·d were recorded in August, i.e., in the period of cyanobacteria predominance with the maximal contents of TOC (51.4 ± 2.1% TS), sugars (599 ± 42 mg/g TS), and lipids (126 ± 13 mg/g TS) in the biomass. In contrast, the lowest biomethanation efficiency was determined in October under diatom prevalence. A strong correlation was found between taxonomic, structural, and chemical properties of the substrate, and anaerobic digestion efficiency. This study’s findings underscore the enormous potential of phytoplankton biomass from summer blooms for energy production as a crucial element of sustainable management of coastal ecosystems and the circular economy. Full article

The Bełchatów Lignite Mine (BLM) in central Poland, one of Europe’s largest Neogene lignite deposits, provides key insights into palaeofloral evolution. Located in the Kleszczów Graben, the BLM consists of four distinct lithological units: subcoal, coal, clayey-coal, and clayey-sandy units. The study presents a palynological investigation of 31 samples from all units, identifying 78 sporomorph taxa, including 10 plant spores, 15 gymnosperm pollen, and 53 angiosperm pollen taxa. Pollen grains from angiosperms and gymnosperms were consistently observed in all samples, while plant spores were scarce. The analysis reveals three distinct palynological zones, reflecting shifts in vegetation. The first zone is characterized by swamp, riparian, and mixed mesophilous forests, dominated by Taxodium/Glyptostrobus, Ulmus, Carya, Engelhardia, Pterocarya, and Quercus. In the second zone, slightly cooler climatic conditions led to the decline of Taxodium/Glyptostrobus and Alnus, indicating a deterioration of swamp forests. The third zone marks a subsequent recovery of these forests. Palaeoclimatic interpretations indicate three phases: a subtropical-humid climate during the Early Miocene, fluctuating humidity in the late Early Miocene, and a transition to a warm-temperate and humid climate in the Late Miocene. Full article

This study aimed to evaluate the potential benefits of co-digesting rapeseed oil cake, a by-product of biodiesel production, with microalgal biomass. Anaerobic fermentation was carried out under mesophilic conditions using various doses of press residue as a co-substrate. The results demonstrate that the addition of rapeseed oil cake enhances biogas production. The highest biogas yield was achieved during co-digestion with 1 g VS·L⁻¹ of microalgal biomass and 0.5 g VS·L⁻¹ of rapeseed oil cake. The average methane content in the biogas was 62.42%. The average hydrogen sulfide concentration ranged from 400 to 700 ppm. The maximum energy yield of 3.76 kWh·kg⁻¹ DM was obtained from co-digesting microalgal and rapeseed oil cake biomass in a 2:1 ratio. Full article

Anaerobic digestion (AD) is an environmentally friendly, promising solution for the recycling of agro-industrial wastes. However, overloading an anaerobic digester with substrate may cause the inhibition of the AD process. The present study investigated the effects of the substrate/inoculum (S/I) ratio on the AD of potato chip processing (PCP) waste from the potato chip processing industry (PCPI). The PCP waste included expired potato chips (EPCs), recovered potato starch (RPS), and potato peel (PP). Mesophilic AD was carried out in batch-wise static reactors at 35 ± 1 °C using four different S/I ratios (0.5, 1.0, 1.5, and 2.0 g VS/g VS) for each type of waste. Different optimum S/I ratios were obtained for the different wastes; however, the pH ranges were comparable (7.0 to 7.5) for all batches. The optimum S/I ratios for EPCs, RPS, and PP were 1.0, 1.5, and 2.0, respectively. The cumulative biogas yields for EPCs, RPS, and PP were 367.5 ± 6.3, 310.0 ± 5.5, and 202.5 ± 4.9 mL/g VS added, respectively. The methane content of the biogas yields ranged between 60% and 70%. There was a variable remarkable shift in the microbial population at the optimum S/I ratio of each type of waste. The abundance of Firmicutes increased in the case of EPCs and RPS but decreased in the case of PP. Conversely, Proteobacteria increased when using PP as a substrate and decreased in the case of EPCs. Herein, the results of the AD of PCP wastes confirm its potential for the onsite production of renewable bioenergy and reductions in energy bills in the PCPI. In addition, this study provides guidance for optimizing the AD of PCP wastes for large-scale applications. Full article

This study was conducted to investigate the effect of hydrogen peroxide (H₂O₂) pretreatment on the anaerobic digestion performance of dairy wastewater. Initial physicochemical characterization revealed that the substrate is highly enriched in volatile solids (approximately 90.67%), indicating its strong potential for anaerobic biodegradation. Given this favorable composition, biochemical methane potential (BMP) assays were performed under mesophilic conditions (37 °C) to quantify biogas and methane generation from the untreated and pretreated dairy effluent. To enhance substrate biodegradability and increase methane yield, an oxidative pretreatment using various doses of H₂O₂ was applied. This pretreatment aimed to disrupt the complex organic matter and promote the solubilization of chemical oxygen demand (COD), especially in its soluble form (sCOD), which is more readily assimilated by methanogenic microorganisms. The experimental results demonstrated a significant improvement in biogas production efficiency. While the untreated sample yielded approximately 100 mL CH₄/g VS, the pretreated substrate achieved a maximum of 168 mL CH₄/g VS, marking a substantial enhancement. Gas composition analysis further revealed that methane accounted for nearly 45% of the total biogas produced under optimal conditions. The dosage of 0.2 g H₂O₂ per g of volatile solids (VS) resulted in the highest improvement in methane production after thermal treatment C1, followed by 1.35 g H₂O₂/g VS, and then 0.5 g H₂O₂/g VS. Furthermore, the kinetics of methane production were assessed by fitting the experimental data to the modified Gompertz model. This model enabled the determination of key parameters, such as the maximum specific methane production rate and the duration of the lag phase. The high coefficient of determination (R²) values obtained confirmed the excellent agreement between the experimental data and the model predictions, highlighting the robustness and reliability of the modified Gompertz model in describing the anaerobic digestion process of dairy waste subjected to oxidative pretreatment. Full article

The search for natural additives from underutilized halophytes and fruit by-products aligns with circular economy principles, addressing consumer demand for healthier and more sustainable alternatives to salt and synthetic antioxidants in foods. Salicornia ramosissima, a halophytic plant rich in minerals, and Malpighia emarginata (acerola), a fruit rich in bioactive compounds, were selected for their potential to enhance meat preservation while reducing reliance on conventional salt and chemical additives. This study evaluated the effects of replacing salt with S. ramosissima powder (1% and 2%) and adding acerola extract (0.3%) in Mertolenga D.O.P. beef hamburgers. Control, 1% salt, acerola, and salicornia formulations were analyzed over 10 days for the following: (1) microbial counts (mesophiles, psychrotrophics, Enterobacteriaceae, Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria, fungi, Salmonella spp., and E. coli); (2) physicochemical parameters (pH, a_w, and CIE-Lab color); and (3) sensory attributes (odor, color, and freshness). Higher Salicornia concentrations negatively affected color (lower a* values) and sensory perception (darker appearance). Acerola extract improved color stability and delayed the development of off-odors, contributing to higher freshness scores throughout storage. No significant differences in microbial counts were observed between treatments. Overall, acerola and low-dose Salicornia showed potential as natural ingredients for meat preservation, with minimal impact on physicochemical and microbiological quality. These findings support the use of halophytes and fruit extracts in sustainable meat preservation strategies. Full article

This study investigated the microbiological, physicochemical, textural, and sensory characteristics of ayran and kefir samples produced from milk treated with different doses of UV-C radiation. For this purpose, raw milk was passed through a UV-C column at three different flow rates (15, 30, and 45 mL/min), and irradiated with doses of 72, 36, and 24 J/mL, respectively, corresponding to the flow rate. Samples produced from milk pasteurised by thermal treatment were used as the control group. This research indicated that UV-C treatment effectively reduced the microbial load in milk to a level comparable to that achieved through conventional pasteurisation. A reduction of 2.15 log cfu/mL in total aerobic mesophilic bacteria count was achieved, while total coliform group bacteria counts were decreased to an undetectable level. Samples produced from milk treated with UV-C showed lower pH and higher titration acidity (% lactic acid). Furthermore, the organic acid content was higher in these samples. Lactic acid, the main organic acid, levels in the ayran and kefir samples were measured at their highest as 11,951.51 mg/kg and 12,989.34 mg/kg, respectively, in the UV45 sample with a radiation dose of 24 J/mL. The treatment of UV-C resulted in a minor change in the colour and textural properties of the samples. Nonetheless, this change was not significant enough to influence consumer acceptance. The application of UV-C to raw milk, depending on the radiation level used, can enhance the fermentation process in the production of ayran and kefir. This study showed that the application of UV-C has improved the quality of drinkable fermented milk products. This research has shown that, while reducing nutritional losses caused by thermal processing, microbial safety is obtained at an approximate value similar to pasteurisation. As a result, UV-C application decreases the loss of dietary compounds and provides an alternative method for microbial inactivation. Full article

Three fungal strains belonging to the genus Penicillium from different temperature classes (two Antarctic strains—psychrotolerant and mesophilic, and a temperate mesophilic) were used to investigate their metabolic cell response to cold stress. The exponential- and stationary-growth-phase fungal cultures were exposed to a transient temperature downshift from optimal to 6 and 15 °C, respectively. The activity of the enzymes hexokinase, glucose-6-phosphate dehydrogenase, and glyceraldehyde 3-phosphate dehydrogenase from the glycolytic pathway, and that of the enzymes isocitrate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase from the TCA cycle were studied. In all experiments, the cold-induced oxidative stress increased the indicated enzymatic activities depending on the strain’s temperature characteristics, the degree of stress, and the growth phase. Furthermore, enzyme activity was lower in cells from stationary-phase cultures (older cells) compared to those from exponential-phase cultures (younger cells). The cellular response was more pronounced in mesophilic strains, regardless of the location of isolation. The cold-adapted Antarctic psychrotolerant strain exhibited enhanced tolerance to low-temperature stress compared to mesophilic strains. These findings emphasize the significance of temperature preferences and growth phase in the survival of fungi under conditions of cold-induced oxidative stress. New information could prove beneficial in forecasting the behaviour of fungal pathogens such as plant pathogens in agriculture and human pathogens in medicine. Full article

Access to microbiologically safe water in preschool educational settings constitutes a pressing public health challenge, particularly in rural areas with deficient infrastructure. Repeated exposure to enteropathogens present in contaminated water has been associated with acute gastrointestinal infections, environmental enteropathy, and disruptions in the intestinal microbiota of young children. Motivated by this concern, the present study evaluates the microbiological quality of water in 32 public preschool facilities in the municipality of Matehuala, San Luis Potosí—18 urban and 14 rural—by analyzing the presence of aerobic mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC), and helminth eggs. The assessment was conducted in accordance with Mexican standards NOM-092-SSA1-1994 and NOM-230-SSA1-2002 and supplemented with the World Health Organization’s guidelines for drinking-water quality. The findings revealed a marked territorial disparity: 100% of rural schools that relied on rooftop water tanks exceeded permissible limits for TC, and 35.7% tested positive for FC. In contrast, all urban schools—supplied through piped water systems—complied with current regulations. Statistical analysis (Mann–Whitney U test, p < 0.05) confirmed significant differences in microbiological contamination based on geographic location and type of water supply. In all FC-positive cases, a lack of sewage infrastructure and inadequate sanitation practices in storage containers were documented. These results demonstrate that formal access to water does not ensure its microbiological safety, particularly in settings with poor structural conditions. The study underscores the urgent need to implement point-of-use water treatment technologies, establish regular microbiological monitoring protocols, and provide training for educational staff in water hygiene practices. Full article

Extending the shelf life and ensuring microbial stability of processed foods are key objectives in the food industry. In this study, edible films containing chitosan, chitosan + thyme (Thymus vulgaris) oil, and chitosan + rosemary (Rosmarinus officinalis) oil were applied to traditional and industrial Cecil cheese using the dipping method, with control groups for each production type. Samples were stored at 4 ± 1 °C for 45 days, and physical (color, water activity, and texture), chemical (pH, acidity, and dry matter), microbiological (total aerobic mesophilic bacteria, yeast-mold, coliforms, and lactic acid bacteria), and sensory analyses were performed on days 1, 15, 30, and 45. Results indicated that chitosan-based films effectively limited microbial growth, with the chitosan + rosemary oil combination being particularly effective in reducing microbial load and maintaining textural stability. Traditional cheeses achieved higher overall acceptability, while purchase intent was greater for industrial products. Coated samples exhibited slower pH decline and more stable dry matter content; industrial cheeses retained moisture more effectively. Texture profile analysis showed more stable chewiness and springiness values in coated samples. In conclusion, natural edible films represent an effective approach for extending shelf life and preserving quality, particularly in traditional cheeses with fibrous structures and shorter shelf lives. Full article

Strains of Aeromonas salmonicida subsp. salmonicida, a major pathogen of salmonids, typically do not grow at temperatures above 30 °C. The effects of thermal stress on this bacterium have been extensively studied. Recently, we demonstrated that repeated exposure to cyclical thermal stress, reaching up to 37 °C, can induce permanent thermoadaptation in certain strains of this bacterium. Many aspects of this adaptation process remain poorly understood. We generated 88 thermoadapted strains of A. salmonicida subsp. salmonicida capable of sustained growth at 33 °C or higher demonstrating that prolonged heat exposure can shift a substantial proportion of psychrophilic strains toward a more mesophilic-like behavior. Although growth at 35 °C was still weaker than in naturally mesophilic A. salmonicida strains, some thermoadapted strains were able to grow up to 37 °C. North American strains harboring the genomic island AsaGEI1a, a known biomarker, exhibited a significantly reduced capacity for thermoadaptation, suggesting a possible genetic constraint, although genomic analyses indicate that AsaGEI1a itself is not directly responsible for this limitation. Genotyping and phenotypic analyses revealed that thermoadaptation is frequently associated with the loss of Type III secretion system and the A-layer, two key virulence factors. Only 7% of the thermoadapted strains retained both features. Overall, our findings suggest that thermoadaptation may represent a potential mechanism influencing the persistence of some psychrophilic A. salmonicida subsp. salmonicida strains in warming aquatic environments under climate change. Full article

Degradation is a key natural attenuation mechanism governing the fate of PPCPs during anaerobic digestion (AD) and subsequent soil exposure. Nevertheless, the combined impact of this sequential treatment (AD followed by land application) remains poorly understood. This study evaluated the degradation characteristics of nine PPCPs during mesophilic AD in three distinct soil types. The concentration changes in the nine PPCPs were monitored after 0, 5, 10, 15, 20, 25, and 30 days of anaerobic incubation at 38 °C, as well as after 0, 2, 5, 8, 10, 12, 15, 20, and 30 days of dark incubation at 25 °C with humidity at 75% in three soils. AD effectively removed sulfamethoxydiazine, ciprofloxacin, and oxytetracycline (>80%). The removal efficiencies for carbamazepine, progesterone, triclosan, naproxen, and megestrol acetate were relatively poor, with the removal rates ranging from 50% to 80%, while gemfibrozil exhibited minimal degradation (<50%). The degradation behavior of nine PPCPs fits well with first-order kinetic equations. Calculated half-lives (days) in the three soils were as follows: sulfamethoxydiazine (20.39 to 23.10), carbamazepine (36.48 to 77.02), megestrol acetate (11.18 to 20.39), progesterone (6.08 to 23.90), ciprofloxacin (11.75 to 63.01), oxytetracycline (13.08 to 30.14), naproxen (7.79 to 40.77), gemfibrozil (8.45 to 30.14), and triclosan (14.75 to 46.21). The corresponding R² values ranged from 0.8882 to 0.9320 for sulfamethoxydiazine, 0.8579 to 0.9248 for carbamazepine, 0.8745 to 0.9658 for megestrol acetate, 0.9026 to 0.9560 for progesterone, 0.8147 to 0.9571 for ciprofloxacin, 0.8136 to 0.9063 for oxytetracycline, 0.8961 to 0.9156 for naproxen, 0.8802 to 0.9497 for gemfibrozil, and 0.9099 to 0.9457 for triclosan. Soil physicochemical properties significantly influenced PPCP degradation rates. Gemfibrozil warrants immediate attention due to its poor degradation; the five PPCPs presenting moderate concern—namely carbamazepine, ciprofloxacin, oxytetracycline, naproxen, and triclosan—require further risk assessment, while sulfamethoxydiazine, megestrol acetate, and progesterone pose low persistence risk according to current evidence. Full article

Grain processing requires sustainable and innovative alternatives. Germination, which enhances the nutritional value of grains, can also increase the microbial load, posing a challenge to food safety. In quinoa, a superfood with an exceptional nutritional profile, germination could maximize its benefits if proper methods are applied to ensure safety. The effects of different disinfection methods on mesophilic aerobic bacteria, enterobacteria, and the germination capacity of two Peruvian quinoa varieties (Rosada de Huancayo (RH) and Pasankalla (PK)) were evaluated for germinated flour production. Seven treatments were applied: four with chemical agents (200 ppm sodium hypochlorite, 4% acetic acid, 8% H₂O₂, and 70% alcohol) and three combined methods (sodium hypochlorite with ultrasound (35 kHz, 15 or 30 min), and hot water (50 °C) with H₂O₂ (2%) and acetic acid (0.1%)). All treatments significantly reduced mesophilic aerobic bacteria (1.29–4.08 log CFU/g), except alcohol (PK, RH) and sodium hypochlorite (PK). Reductions in enterobacteria (p < 0.05) ranged from 1.78 to 3.55 log CFU/g in RH; in PK, only the hot water + 2 chemical agents or 8% H₂O₂ treatments achieved significant reductions. The most effective treatment was hot water with H₂O₂ and acetic acid, which reduced bacteria and improved germination. Full article

This study evaluated chemical and physical parameters, volatile fatty acids (VFAs), pathogens indicators, ammonia, and greenhouse gas (GHG: CO₂, CH₄, N₂O) emissions from fresh and digested dairy manure under controlled laboratory conditions, simulating storage at 18 °C and 28 °C. Manure and digestate samples were collected during summer 2023 from three dairy farms in Northern Italy, all operating similar mono-substrate, mesophilic anaerobic digesters at 42 °C with short hydraulic retention times (HRT) of ~30 days, instead of the longer HRTs commonly used (up to 90 days). Gas emissions were measured using a static chamber method over 40 min sessions, and cumulative GHG losses were converted to CO₂ equivalents. Anaerobic digestion significantly increased ammonia emissions (p < 0.001), in comparison with fresh manure samples. Anaerobic digestion affected pH variations, while reducing CH₄ and N₂O emissions by up to 67% and 50%, respectively. Storage at 28 °C increased total GHG fluxes by 74% for fresh manure and 66% for digestate. Residual methane emissions suggest incomplete digestion, likely due to short HRT and low digestion temperatures. Among pathogens, only clostridia showed significant reduction post-digestion. Overall, anaerobic digestion effectively lowers the global warming potential (GWP) of dairy manure, but higher environmental temperatures exacerbate ammonia and GHG emissions during storage, highlighting the need for optimized post-digestion handling in warm climates. Full article