Search Results (283)

Micro(nano)plastics are important emerging contaminants and a current research hotspot in the environmental field. Micro(nano)plastics widely exist in various organic wastes such as waste sludge, food waste (FW) and livestock manure and often enter into digesters along with anaerobic digestion (AD) treatment of these wastes, thereby exerting extensive and profound influences on anaerobic process performance. This study reviews sources of micro(nano)plastics and their pathways entering the anaerobic system and summarizes the quantities, sizes, shapes and micromorphology of various micro(nano)plastics in waste sludge, FW, livestock manure, yard waste and municipal solid waste. The current advances on the effects of multiple micro(nano)plastics mainly polyvinyl chloride (PVC), polystyrene (PS) and polyethylene (PE) with different sizes and quantities (or concentrations) on AD of organic wastes in terms of methane production, organic acid degradation and process stability are comprehensively overviewed and mechanisms of micro(nano)plastics affecting AD involved in microbial cells, key enzymes, microbial communities and antibiotic resistance genes are analyzed. Meanwhile, coupling effects of micro(nano)plastics with some typical pollutants such as antibiotics and heavy metals on AD are also reviewed. Due to the extreme complexity of the anaerobic system, current research still lacks full understanding concerning composite influences of different types, sizes and concentrations of micro(nano)plastics on AD under various operating modes. Future research should focus on elucidating mechanisms of micro(nano)plastics affecting organic metabolic pathways and the expression of specific functional genes of microorganisms, exploring the fate and transformation of micro(nano)plastics along waste streams including but not limited to AD, investigating the interaction between micro(nano)plastics and other emerging contaminants (such as perfluorooctanoic acid and perfluorooctane sulphonate) and their coupling effects on anaerobic systems, and developing accurate detection and quantification methods for micro(nano)plastics and technologies for eliminating the negative impacts of micro(nano)plastics on AD. Full article

Bioleaching, mediated by selected microflora, offers a more environmentally friendly and cost-effective alternative to traditional mining techniques by transforming metals from sulfide ores into water-soluble forms. Pyrite ores often contain valuable rare or noble metals, such as gold (Au), silver (Ag), nickel (Ni), and cobalt (Co), which can be leached through the metabolic activity of specific chemoautotrophic microorganisms. This study investigates the adaptation process of the Acidithiobacillus ferriphilus bacterial strain, originally isolated from acid mine drainage (AMD), for the bioleaching of pyrite. The progress of the bioleaching process was evidenced by the release of iron (3.6 mg/mL) and significant quantities of gold (0.21 mg/L, equivalent to 3 g/t) into the post-culture liquid. The results indicate that the most effective bioleaching was achieved during the final adaptation stage, utilizing a medium with 7% pyrite content and a 0.75% supplement of an easily accessible energy source in the form of iron sulfate. These findings confirm the potential of the A. ferriphilus strain for pyrite bioleaching. Full article

Background: Aggregatibacter actinomycetemcomitans JP2 genotype is a virulent pathogen linked to severe periodontitis and systemic diseases. Honey and royal jelly (RJ) have demonstrated bioactive properties against this microorganism. This study aims to assess the bioactive properties of honeys and RJ against this key periodontal pathogen and to preliminarily identify key compounds with antibacterial potential. Methods: The antibacterial activity of honeys and commercial products (manuka, L-Mesitran^® as a medical-grade honey-based formulation (MGHF), and Honix^® RJ) against A. actinomycetemcomitans JP2 was evaluated using the agar well diffusion method and microdilution assays. Extensive physicochemical characterization (e.g., hydrogen peroxide level, total phenolic content, and total flavonoid content) was conducted to correlate the bioactive compounds with the antimicrobial activity. Results: All tested samples exhibited varying antibacterial potency, with inhibition zones ranging from 21 to 37 mm. The MICs ranged from 40.7 to 104.3 mg/mL. MGHF, RJ, and multifloral honeys showed the lowest MICs. The pH of six out of eight samples could not induce enamel decalcification while the pH of three samples may not influence cementum demineralization. Vitamin C, zinc, magnesium, and potassium were present in measurable quantities, and were not associated with significant antibacterial activity. MGHF showed the highest hydrogen peroxide activity and TFC values. TFC and H₂O₂ content were statistically correlated with lower MIC values. Conclusions: Honey and RJ showed antibacterial activity against A. actinomycetemcomitans JP2, partly attributed to their content of hydrogen peroxide and flavonoids. Clinical trials are needed to confirm the potential role of honey, RJ, and their bioactive compounds in managing periodontitis. Full article

The bacterial diversity of soils cultivated with avocado (Persea americana M.) is influenced by different factors, perhaps the most decisive being the type of agronomic management used by farmers. In conventional agronomic management (CM), high doses of agrochemicals are applied, in contrast to organic agronomic management (OM), where organic fertilizers are used. This alters the diversity and abundance of soil microorganism populations, which in turn affects crop health. This study aimed to isolate and morphologically characterize rhizospheric bacteria from avocado trees under different agronomic management systems (CM and OM). For the bacterial isolates, their ability to promote plant growth in vitro was determined through biochemical tests for phosphorus and calcium solubilization and nitrogen fixation. In addition, their in vivo effect on tomato (S. lycopersicum) growth was evaluated, and their antagonistic capacity against Fusarium sp. was assessed. The results showed differences in the quantity, diversity, and morphologies of bacterial isolates depending on the type of agronomic management. A higher Shannon diversity index was found in OM (2.44) compared to CM (1.75). A total of 35 bacterial isolates were obtained from both management types. A greater number of isolates from OM soils exhibited in vitro PGP activity; notably, eight isolates from OM plots showed phosphate-solubilizing activity, compared to only one from CM plots. Furthermore, although all isolates demonstrated nitrogen fixing capacity, those from OM orchards produced significantly higher nitrate levels than the control (Azospirillum vinelandii). On the other hand, inoculation of tomato plants with bacterial isolates from OM soils increased plant height, root length, and total fresh and dry biomass compared to isolates from CM soils. Likewise, OM isolates exhibited greater antagonistic activity against Fusarium sp. These findings demonstrate the impact of agronomic management on soil bacterial populations and its effect on plant growth and protection against pathogens. Full article

Brewer’s spent grain (BSG) is the main solid byproduct of the brewing industry, generated in large quantities worldwide. Its high organic content and availability make it an attractive substrate for biotechnological valorization and recycling within a circular economy framework, contributing to the recovery and reuse of agro-industrial residues. This study investigates the potential of Talaromyces stollii I05.06 to simultaneously produce laccase and release phenolic compounds through submerged fermentation (SmF) using BSG as the sole carbon source. Initial SmF trials confirmed the fungus’s capacity to metabolize BSG. Subsequent fermentations with phosphate buffer supplementation (100 mM) significantly enhanced laccase activity (1535 ± 151.6 U·L⁻¹ on day 5) and phenolic content (6.28 ± 0.07 mg GAE per 100 g on day 1 with 50 mM buffer). However, the addition of typical laccase inducers (Cu²⁺ and Mn²⁺) led to inhibitory effects. The results highlight T. stollii I05.06 as a promising microorganism for the integrated valorization of BSG, contributing to sustainable agro-industrial waste management and the development of value-added bioproducts. Full article

In recent years, the application of sustainable cementitious materials has become of great importance to improve buildings efficiency and to achieve carbon neutrality. Main goal of this work to study and develop BIOAERMAC, an innovative construction material with low density, composed of synthetic anhydrous calcium sulfate obtained as by-product in the industrial production of hydrofluoric acid and an aerating agent composed of microorganisms and peroxides, with the addition of rubber from end-of-life tires (ELTs). A density from 600 to 950 kg/m³ with a compressive strength up to 6.0 MPa and a thermal conductivity from 0.15 to 0.3 W/mK are the key performance metrics of BIOAERMAC composites. Experimental results showed an improvement in technical and energy performance, combined with a reduction in natural resource consumption and the wide quantity of by-product reintroduced into the production process. Full article

Reducing post-harvest losses of cereal crops is a key challenge for ensuring global food security amid the limited arable land and growing population. This study investigates the effectiveness of electron beam irradiation (5 MeV, ILU-10 accelerator) as a physical decontamination method for various cereal crops cultivated in Kazakhstan. Samples were irradiated at doses ranging from 1 to 5 kGy, and microbiological indicators—including Quantity of Mesophilic Aerobic and Facultative Anaerobic Microorganisms (QMAFAnM), yeasts, and molds—were quantified according to national standards. Experimental results demonstrated an exponential decline in microbial contamination, with a >99% reduction achieved at doses of 4–5 kGy. The modeled inactivation kinetics showed strong agreement with the experimental data: R² = 0.995 for QMAFAnM and R² = 0.948 for mold, confirming the reliability of the exponential decay models. Additionally, key quality parameters—including protein content, moisture, and gluten—were evaluated post-irradiation. The results showed that protein levels remained largely stable across all doses, while slight but statistically insignificant fluctuations were observed in moisture and gluten contents. Principal component analysis and scatterplot matrix visualization confirmed clustering patterns related to radiation dose and crop type. The findings substantiate the feasibility of electron beam treatment as a scalable and safe technology for improving the microbiological quality and storage stability of cereal crops. Full article

This study introduces an advanced strategy for improving microbial fuel cell (MFC) performance in hexavalent chromium (Cr(VI)) wastewater treatment. A high-performance nano-iron sulfide (nano-FeS) hybridized biocathode was developed by regulating glucose concentration and applying an external voltage. The combination of a glucose concentration of 1000 mg/L and a 0.2 V applied voltage greatly promoted the in situ biosynthesis of nano-FeS, resulting in smaller particle sizes and increased quantities within the biocathode, leading to enhanced electrochemical performance. The MFC with the hybridized biocathode exhibited the highest power density (43.45 ± 1.69 mW/m²) and Cr(VI) removal rate (3.99 ± 0.09 mg/L·h), outperforming the control by 29% and 71%, respectively. The improvements were attributed to the following processes. (1) Nano-FeS provided additional active sites that enhanced electron transfer and electrocatalytic activity, reducing cathode passivation; (2) it protected microorganisms by reducing Cr(VI) toxicity, promoting redox-active substance enrichment and antioxidant enzyme secretion, which maintained microbial activity; (3) the biocathode selectively enriched electroactive and Cr(VI)-reducing bacteria (such as Brucella), fostering a stable and symbiotic microbial community. This study highlights the promising potential of regulating carbon source and external voltage to boost nano-FeS biosynthesis, offering a sustainable and efficient strategy for MFC-based Cr(VI) wastewater treatment with practical implications. Full article

Crop diseases negatively affect the quality and quantity of agricultural products, with significant economic and social consequences. These problems become emergencies in a world where the safe production of food for human health is becoming increasingly pressing. Microorganisms, including phytopathogenic fungi, are the main organisms responsible for these diseases, which cause devastating damage. Environmental pollution generated by human activities causes further significant reductions in agricultural production, as well as the expansion of metropolitan areas, and climate change. Phytotoxins produced by pathogenic fungi play a fundamental role in the induction of diseases by directly interfering with the physiological processes of agricultural plants. They are secondary metabolites that can belong to all the different classes of natural compounds, and their structures and biological activities have been extensively studied. These substances have often been shown to possess other interesting biological activities for potential applications both in agriculture and in other fields, such as biotechnology and medicine. This review focuses on phytotoxic α-pyrones produced by plant pathogenic fungi, describing in detail all their chemical and biological properties and, in some cases, the results of studies on their structure-activity relationship and on the potential practical applications in various sectors. Full article

The growing scarcity of freshwater has accelerated the global deployment of desalination technologies, especially reverse osmosis (RO), as an alternative to meet increasing water demands. However, this process generates substantial quantities of brine—a hypersaline waste stream that can severely impact marine ecosystems if improperly managed. This perspective review explores the use of urease-driven Microbially Induced Carbonate Precipitation (MICP) as a biotechnological solution aligned with circular economy principles for the treatment and valorization of RO brines. Through the enzymatic activity of ureolytic microorganisms, MICP promotes the precipitation of calcium carbonate and other mineral phases, enabling the recovery of valuable elements and reducing environmental burdens. Beyond mineral capture, MICP shows promise in the stabilization of toxic metals and potential integration with microbial electrochemical systems for energy applications. This review summarizes current developments, identifies existing challenges, such as microbial performance in saline conditions and reliance on conventional urea sources, and proposes future directions focused on strain optimization, nutrient recycling, and process scalability for sustainable implementation. Full article

Intensive research has been conducted for many years to develop environmentally friendly techniques for plant cultivation that optimize the fertilization process. One of the most promising areas within the fertilizer industry is using microbiologically enriched fertilizers, which incorporate beneficial bacteria or fungi. Biofertilizers are the focus of studies on both their production technologies and their effects on crop growth and yield, presenting a potential alternative to conventional mineral fertilizers. The prolonged and improper use of mineral fertilizers, along with inadequate plant protection, a lack of organic fertilization, and poor crop rotation practices, negatively impact soil health, disrupting microbial populations and ultimately diminishing yield quality and quantity. Microorganisms, particularly specific groups known as plant growth -promoting rhizobacteria (PGPR) and beneficial fungi, are estimated to make up 85% of the total soil biomass and play a crucial role in soil fertility by mineralizing organic matter, suppressing pests and pathogens, forming humus, and maintaining proper soil structure. They also provide optimal conditions for plant growth. Soil microorganisms can be categorized as either autochthonous, naturally present in the soil, or zymogenic, which develop when easily assimilable organic matter is added. Key microorganisms such as Micrococcus, Bacillus, Azotobacter, and nitrogen-fixing bacteria like Rhizobium and Bradyrhizobium significantly contribute to soil health and plant growth. Microbially enhanced fertilizers not only supply essential macro- and micronutrients but also improve soil quality, enhance nutrient use efficiency, protect plants against pathogens, and restore natural soil fertility, fostering a balanced biological environment for sustainable agriculture. Full article

Adolescence represents a critical developmental stage where diet, gut microorganisms, and mental health are strongly interconnected. The current literature evidences the bidirectional role between dietary habits and psychological well-being, which is mediated by the gut–brain axis. The purpose of this review is to highlight the importance of dietary habits in adolescence period and the impact of different food choices on microbiota and secondary on mental health. Gut microbiota plays a vital role in the synthesis of neurotransmitters such as serotonin, dopamine, noradrenaline, and metabolites like short-chain fatty acids (SCFAs). The disruption in the composition of microbiota is called dysbiosis, which has been associated with a systemic inflammation state and chronic stress. They contribute to the onset of psychiatric disorders including MDD, anxiety, ADHD, and autism. Diets with a high quantity of sugar and low fiber contribute to alteration of microbiota and poor mental health. Additionally, early-life stress, antibiotic usage, and chronic inflammation may alter bacterial communities, with long-term implications for adolescents mental health. Dietary interventions, including the intake of prebiotics, probiotics, SCFAs, and micronutrients could restore microbial balance and improve psychiatric symptoms. This literature review highlights the critical role of diet and gut microbiota for adolescent mental health and emphasizes the need for integrative strategies to promote psychological resilience through microbiome regulation. Full article

Cacao mucilage is a rich medium for microbial development due to the presence of various sugars, water, pectin, mineral salts, and yeasts of the Saccharomyces cerevisiae type. This study aims to provide added value to this commonly discarded residue, thereby contributing to the economic growth of the Rio Chila area in the Valencia Canton of Los Ríos Province. The methods applied for developing beer consist of malting, grinding, mashing, filtering, boiling, cooling, fermentation (during which cacao mucilage is added), and maturation, followed by physical–chemical analyses. The Fine aroma cacao mucilage presented values of 0.66% acidity, 7.63 °Brix, pH 4.43, absorbance 1.13, transmittance 23.67%, suspended solids 0.04 g: 2.66%, density 1.07 g/mL, turbidity 6.94 NTU, °GL 8.47% vol., foam quantity 1.70 cm, colorimetry L* 50.77, colorimetry a* 18.08, colorimetry b* 50.53, and bitterness degree 39.00. The analyses presented values within the normal parameters applied to beers at the national level (INEN standards). Escherichia coli, Salmonella, and total microorganisms showed no contamination in the microbiological analyses. In the sensory analyses, appearance, aroma, flavour, and mouthfeel were evaluated, with the best experiment being the combination of Fine aroma cacao with a concentration of 30% mucilage and added Cascade hops. This study took into account the concentrations of cacao mucilage (20% and 30%) from the varieties (Fine aroma and CCN-51), as well as the addition of the brewing hops Cascade and Northern Brewer. Regarding the physicochemical characteristics, adding this cacao derivative did not affect craft beer and conformed to the ranges of the NTE INEN 2262 standard. Thus, this research proposes an alternative use for cocoa mucilage, contributing to waste reduction and broadening its potential applications. Full article

Spent mushroom substrate (SMS) is the residual biomass generated after harvesting the fruitbodies of edible fungi. It is produced in large quantities and contains abundant nutrients. Plant growth-promoting rhizobacteria (PGPR) are a group of plant-associated microorganisms known for their ability to enhance plant growth, improve disease resistance, and boost soil quality. In this study, three PGPR strains with the highest plant growth-promoting potential were selected based on their ability to grow effectively in SMS extract. The SMS substrates were mixed with PGPR solutions and sterile water to establish a batch culture system. The mixture was initially incubated at 28 °C for 3 days, followed by continuous aerobic decomposition in a ventilated environment for 180 days. Based on the quality analysis of the PGPR-treated SMS, the 54-day treatment for transplanting blueberry seedlings was selected. The PGPR-treated substrates showed significantly higher TN, HN, and AP than controls (p < 0.05), suggesting a potential role of PGPR in enhancing nutrient availability. Alpha diversity index analysis revealed significant differences in microbial diversity between the PGPR-treated substrates and the control. Furthermore, the PGPR-treated substrates significantly influenced plant growth characteristics, soil nutrient content, and rhizosphere microbial diversity. Enhanced plant growth characteristics were strongly correlated with increased soil nutrient levels, suggesting a potential link between rhizospheric microbial communities and plant growth performance. This study provides a novel approach and experimental framework for the utilization of SMS and the development of PGPR-based biofertilizers, offering valuable insights into sustainable agricultural practices. Full article

Chile, one of the top global wine producers, produces a significant quantity of grape pomace waste, composed primarily of peels and seeds, of which their management includes many environmental challenges. Composting offers a sustainable waste management solution, converting organic waste into a rich nutrient and beneficial microorganisms for soil amendment. This study compared traditional turning and static forced aeration composting systems using a mix of grape pomace (70 m³), wheat straw (15 m³), and manure (15 m³). The results show no significant differences in the final compost chemical quality between the two systems. Nevertheless, forced aeration (T1) influenced the bacterial community, particularly during the thermophilic stage, leading to a major differentiation compared to traditional composting (T0). Similar Shannon index values for bacterial diversity across stages suggest that both composting methods support comparable levels of bacterial diversity. However, the fungal communities exhibited more variability, likely due to the differences in temperature and aeration conditions between the windrows, which are known to affect fungal growth and activity. While both composting methods met the Chilean regulatory standards and achieved high-quality compost, the forced aeration system demonstrated advantages in temperature control, microbial diversity, and pathogen suppression, suggesting its potential for more efficient composting in similar agricultural contexts. Full article