Search Results (56)

Microbially induced carbonate precipitation (MICP) offers an eco-friendly approach to stabilize porous materials. This study evaluates its feasibility for protecting agricultural drainage ditch slopes through laboratory tests. Liquid experiments assessed calcium carbonate (CaCO₃) precipitation rates under varying bacteria–cementation solution ratios (BCR), cementation solution concentrations (1–2 mol/L), and urease inhibitor (NBPT) contents (0–0.3%). Soil experiments further analyzed the effects of solidified layer thickness (4 cm vs. 8 cm) and curing cycles on soil stabilization. The results showed that CaCO₃ precipitation peaked at a BCR of 4:5 and declined when NBPT exceeded 0.1%. Optimal parameters (0.1% NBPT, 1 mol/L cementation solution, BCR 4:5) were applied to soil tests, revealing that multi-cycle treatments enhanced soil water retention and CaCO₃ content (up to 7.6%) and reduced disintegration rates (by 70%) and permeability (by 83%). A 4 cm solidified layer achieved higher Ca²⁺ utilization, while an 8 cm layer matched or exceeded 4 cm performance with shorter curing. Calcite crystals dominated CaCO₃ formation. Crucially, reagent dosage should approximate four times the target layer’s requirement to ensure efficacy. These findings demonstrate that MICP, when optimized, effectively stabilizes ditch slopes using minimal reagents, providing a sustainable strategy for agricultural soil conservation. Full article

Trehalose, a disaccharide consisting of two D-glucose molecules, is present in a variety of organisms, including bacteria, yeast, fungi, insects, and plants. In plants, it functions as a source of energy and carbon, and in yeast and plants, it serves as a signaling molecule, influencing metabolic pathways and growth regulation. Additionally, it plays a role in protecting proteins and cell membranes from stress-induced damage. This study aims to assess the optimal level of trehalose supplementation in the diets of layer hens aged 34 to 49 weeks, addressing the limited existing literature on its effects on productivity. Experimental diets, designed in accordance with nutritional recommendations, were formulated to contain six different levels of trehalose (0, 0.05, 0.10, 0.30, 0.60, and 1.00%). The study was conducted over five 21-day periods, during which various performance parameters were evaluated. The results indicated that trehalose supplementation at levels of 0.05%, 0.10%, and 0.30% led to increased feed intake (FI) compared to the 1.00% level (p < 0.05). Furthermore, the highest trehalose level (1.00%) significantly reduced the feed conversion ratio by egg mass (FCRem) compared to both the control group and the other supplementation levels; however, the feed conversion ratio by dry matter (FCRDz) remained consistent across all treatments. The levels of 0.05%, 0.10%, and 0.30% exhibited superior FCREm and FCRDz compared to the 1.00% level. Egg weight (EW) was higher in the trehalose-supplemented groups compared to the control group. Additionally, the 1.00% trehalose treatment was found to be the most effective in terms of relative weights of shells (RWS), and egg mass (EM) was higher at all trehalose levels compared to the control group. The antioxidant status, as measured by malondialdehyde (MDA) levels, indicated that supplementation with 0.30% and 0.60% trehalose had a protective effect against oxidative stress, although the 1.00% level resulted in increased MDA levels. Total weight (TW) was highest in the 0.30% treatment group, and bone strength (BS) improved in the groups supplemented with 0.10% and 1.00% trehalose. Other parameters, including lipid content (L), dry matter (DM), phosphorus (P), and calcium (Ca), did not show any significant differences among the treatment groups. In conclusion, supplementation with 1.00% trehalose enhances feed efficiency, egg weight, and quality, with minimal impact on lipid peroxidation, while potentially providing benefits for gut health and egg quality. Full article

Microbial-induced calcium carbonate precipitation is an efficient and environmentally friendly soil stabilization technology. To explore the mineralization performance of carbonate precipitation, this study selects three factors, including the type of cementing solution (TCS), the cementing solution concentration (CSC), and the ratio of bacteria to cementing solution (B/C ratio), to investigate their effects on microbial mineralization. This study reveals the influence of each factor on the amount and rate of carbonate precipitation and analyzes the changes in the characteristics of carbonate precipitation crystals, such as the crystal diameter. The experimental results show that (1) the mineralization effect of magnesium ions and calcium ions results in higher precipitation amounts and rates than copper ions, with less environmental pollution. The concentration of the grout solution is positively correlated with the precipitation amount and negatively correlated with the precipitation rate, while the B/C ratio shows the opposite trend. (2) The crystal diameter of CaCO₃ between crystals reduces as the B/C ratio decreases and the CSC increases. (3) The characteristics of MgCO₃ crystals are mainly affected by the CSC. Both excessively high and low concentrations lead to an increase in crystal diameter. (4) The characteristics of CuCO₃ crystals are relatively stable, with smaller crystal particles maintained at around 1 μm. This study can provide a reference for the reinforcement of different types of soils, offering optimal reinforcement solutions based on the required crystal size, carbonate generation amount, and generation rate. It reduces resource waste and unnecessary chemical use, providing a theoretical foundation for sustainable soil remediation and ecological construction. Full article

Corn, as a raw material supplying energy, plays an important role in animal husbandry. But in recent years, problems related to insufficient energy supply from corn have attracted increasing attention. Therefore, it is highly important to develop new energy-supplying materials to replace corn in animal diets. To study the feasibility of replacing corn with fermented corn straw in ruminants, 16 Yichang white goats were divided into two groups: those kept on a grain-based diet with dry corn straw (DS) and those fed a grain-based diet with fermented corn straw (FS). Corn in the FS group was replaced with fermented corn straw at a ratio of 1.3:1. By increasing the surface area (p = 0.035) and width (p = 0.024) of the rumen epithelial papillae of Yichang white goats, the absolute enzyme activity of carboxymethyl cellulase and the relative enzyme activity of microcrystalline cellulase in the rumen contents increased with fermented corn straw, and the rumen digestibility of cellulose and the whole intestinal apparent digestibility of CP, CF, NDF, ADF, cellulose and hemicellulose increased. The timely removal of excess calcium through feces and urine prevented liver and kidney damage, improved the heart index and liver index, and sustained goat health. Due to an increase in the abundance of beneficial bacteria such as f-Lachnospiraceae and c_Bacilli in the rumen fluid and colon contents, the abundance of potentially harmful bacteria such as s_Turicibacter decreased. Through the rumen pentose phosphate pathway, carbon metabolism, the AMPK signaling pathway, pathways of neurodegeneration, multiple diseases pathways, vitamin b6 metabolism in the colon, the biosynthesis of nucleotide sugars, and the cysteine and methionine metabolism pathways, rumen fermentation and metabolism are regulated in the goat body, promoting animal health. In this study, we systematically evaluated the effects of replacing corn with fermented corn straw on the carcass index, organ index, calcium and phosphorus contents in tissues, serum biochemical parameters, nutrient digestibility, rumen epithelium and intestinal development, rumen fermentation, and microbial enzyme activity of the rumen contents of Yichang white goats. By combining these approaches with microbial 16S amplicon analysis of rumen fluid and colon contents, along with nontargeted metabolome analysis, we demonstrated the feasibility of substituting corn with fermented corn straw in ruminant feed, providing a new approach for the substitution of energy-supplying feed materials. Full article

In the early Cambrian period, a severe greenhouse effect subjected the Gondwanan continents to accelerated erosion, enriching oceanic waters with essential nutrients, including phosphate, silicon, calcium, magnesium, iron, and trace elements. The nutrient flux, sourced from the volcanic composition of west Gondwana, was recorded as sequences of nodular phosphoritic limestones intercalated with chlorite-rich silts, containing ferrous phyllosilicates such as chamosite and chlorite. The abundant and diverse fossil record within these deposits corroborates that the ion supply facilitated robust biogeochemical and nutrient cycling, promoting elevated biological productivity and biodiversity. This paper investigates the early Cambrian nutrient fluxes from the Gondwanan continental region, focusing on the formation of phosphoritic and ferrous facies and the diversity of the fossil record. We estimate and model the biogeochemical cycling within a unique early Cambrian ecosystem located in South Spain, characterized by calcimicrobial reefs interspersed with archaeocyathids that settled atop a tectonically elevated volcano-sedimentary platform. The configuration enclosed a shallow marine lagoon nourished by riverine contributions including ferric and phosphatic complexes. Geochemical analyses revealed varying concentrations of iron (0.14–3.23 wt%), phosphate (0.1–20.0 wt%), and silica (0.27–69.0 wt%) across different facies, with distinct patterns between reef core and lagoonal deposits. Using the Geochemist’s Workbench software and field observations, we estimated that continental andesite weathering rates were approximately 23 times higher than the rates predicted through modeling, delivering, at least, annual fluxes of 0.286 g·cm⁻²·yr⁻¹ for Fe and 0.0146 g·cm⁻²·yr⁻¹ for PO₄³⁻ into the lagoon. The abundant and diverse fossil assemblage, comprising over 20 distinct taxonomic groups dominated by mollusks and small shelly fossils, indicates that this nutrient influx facilitated robust biogeochemical cycling and elevated biological productivity. A carbon budget analysis revealed that while the system produced an estimated 1.49·10¹⁵ g of C over its million-year existence, only about 0.01% was preserved in the rock record. Sulfate-reducing and iron-reducing chemoheterotrophic bacteria played essential roles in organic carbon recycling, with sulfate reduction serving as the dominant degradation pathway, processing approximately 1.55·10¹¹ g of C compared to the 5.94·10⁸ g of C through iron reduction. A stoichiometric analysis based on Redfield ratios suggested significant deviations in the C:P ratios between the different facies and metabolic pathways, ranging from 0.12 to 161.83, reflecting the complex patterns of organic matter preservation and degradation. The formation of phosphorites and ferrous phyllosilicates was primarily controlled by suboxic conditions in the lagoon, where microbial iron reduction destabilized Fe(III)-bearing oxyhydroxide complexes, releasing scavenged phosphate. This analysis of nutrient cycling in the Las Ermitas reef–lagoon system demonstrates how intensified continental weathering and enhanced nutrient fluxes during the early Cambrian created favorable conditions for the development of complex marine ecosystems. The quantified nutrient concentrations, weathering rates, and metabolic patterns established here provide a baseline data for future research addressing the biogeochemical conditions that facilitated the Cambrian explosion and offering new insights into the co-evolution of Earth’s geochemical cycles and early animal communities. Full article

Background/Objectives: Periodontitis is an inflammatory disease induced by bacteria in dental plaque that can activate the host’s immune-inflammatory response and invade the bloodstream. We hypothesized that a higher periodontal inflamed surface area (PISA) is associated with higher levels of inflammatory biomarkers, lower levels of antioxidants, and mitochondrial DNA copy number (mtDNAcn). Methods: Using periodontal parameters, we calculated the PISA score, measured the levels of inflammatory biomarkers and antioxidants in the serum, and took buccal swabs for mtDNA and nuclear DNA (nDNA) extraction. Results: Higher PISA was associated with higher CRP levels, higher leukocyte, neutrophil, and erythrocyte counts, and lower magnesium-to-calcium ratio, but not with mtDNAcn. A higher number of deep pockets was associated with higher leukocytes and neutrophil counts and higher uric acid levels. Conclusions: The PISA score might be an appropriate parameter to assess the inflammatory burden of periodontitis, but not to assess mitochondrial dysfunction after mtDNA isolation from buccal swabs. Full article

Background: Effective management of primary apical periodontitis depends on understanding the dynamic interactions within the root canal microbiome. This study aimed to investigate the effect of sequential antimicrobial phases on the root canal microbiome during a two-visit treatment approach, with a focus on calcium hydroxide medication. Methods: Samples were collected from three teeth across four treatment phases: initial infection (S1), after chemomechanical preparation (S2), after intracanal medication (S3), and after a final flush (S4). DNA was extracted, and the V3–V4 regions of the 16S rRNA gene were sequenced using Illumina MiSeq. Sequencing data were analyzed with QIIME 2, and differentially abundant taxa were identified using linear discriminant analysis effect size (LEfSe). Results: While microbial community composition did not differ significantly between phases, the Firmicutes/Bacteroidetes ratio decreased after the antimicrobial stages. LEfSe analysis revealed higher abundances of Lactobacillales, Arthrobacter, and Veillonella in the untreated (CMP) group. Bifidobacterium longum was relatively more abundant in the intracanal medication (ICM) phase, and Dorea formicigenerans was more abundant in the final-flush (FF) phase. Conclusions: Although calcium hydroxide treatment did not induce statistically significant changes in overall root canal microbial composition, trends such as a reduction in the Firmicutes/Bacteroidetes ratio and a relative increase in Bifidobacterium longum numbers suggest potential ecological shifts. The observed relative increase in Bifidobacterium longum numbers may represent a hypothesis-driven observation reflecting indirect ecological effects rather than direct pH modulation. While visual patterns (e.g., PCA clustering) were observed, they lacked statistical support. Further studies with larger sample sizes are needed to validate these observations and assess the potential role of beneficial bacteria in root canal treatments. Full article

The porous particles prepared from composited calcium–ortho-phosphate (biphasic), Thai silk fibroin, gelatin, and alginate, with an organic to inorganic component ratio of 15.5:84.5, were tested for their abilities to control the release of the commercialized antibiotic solutions, clindamycin phosphate (CDP) and amikacin sulfate (AMK). The in vitro biodegradability tests complying to the ISO 10993-13:2010 standard showed that the particles degraded <20 wt% within 56 days. The drugs were loaded through a simple adsorption, with the maximum loading of injection-graded drug solution of 43.41 wt% for CDP, and 39.08 wt% for AMK. The release profiles from dissolution tests of the drug-loaded particles varied based on the adsorption methods used. The drug-loaded particles (without a drying step) released the drug immediately, while the drying process after the drug loading resulted in the sustained-release capability of the particles. The model-fitting of drug release profiles showed the release driven by diffusion with the first-ordered kinetic after the initial burst release. The released CDF and AMK from particles could sustain the inhibition of Gram-positive bacteria and Gram-negative bacteria, respectively, for at least 72 h. These results indicated the potential of these composited particles as controlled-release carriers for CDP and AMK. Full article

Bacterial chondronecrosis with osteomyelitis (BCO) lameness is a major welfare issue for broiler production worldwide affecting approximately 1.5% of broilers over 42 days old. Excessive body weight gain causes mechanical stress on long bones, leading to micro-fractures. This condition induces a bacterial infection of fractures, resulting in bone necrosis and eventual BCO lameness. Increasing gut integrity and supporting Calcium metabolism contribute to the optimal bone structure and subsequently reduce BCO lameness. Probiotics thus provide an excellent strategy for alleviating BCO due to the improvement of intestinal integrity and barrier function. Accordingly, the present study investigated the lameness reduction through the feed supplementation of a selected probiotic. Broiler chickens were assigned to three treatments, including a control litter group (FL), a PoultryStar^®Bro probiotic fed group (BRO), and a control wire-flooring group (CW) designed to induce BCO lameness. The probiotic significantly decreased lameness by 46% compared to the control group (p < 0.05). The most predominant bacteria identified from the BCO lesions were Staphylococcus cohnii and Staphylococcus lentus. Moreover, significant increments of tight junction gene expression in jejunum and ileum, plus numerical improvements of body weight gain (BW; +360 g) and feed conversion ratio (FCR; −12 pts) were observed in BRO-supplemented birds. Full article

Alkali-activated slag (AAS) materials are one of the most promising sustainable construction composites. These novel materials are highly characterized by their improved mechanical and durability properties. Nevertheless, the high shrinkage rate hinders their full-scale applications. The low Ca/Si ratio, complex hydration process, and fine pore microstructure are the main causes of the reported shrinkage behavior. This study introduces Bacillus subtilis culture for healing the cracking behavior. The enzymatic action leads to precipitating calcium carbonate crystals that fill AAS cracks and pores. Incorporating calcium oxide has been recommended in multiple studies. The main purpose of adding calcium oxide is to enhance the engineering properties of AAS and provide more calcium ions for the biochemical reactions induced by the added bacteria. However, inconsistent findings about the influence of calcium oxide have been reported. This research provides further insights into the effect of calcium oxide (CaO) on the performance of microbial self-healing efficiency in AAS composite. The results highlight that incorporating calcium oxide as 7% of the binder partial replacement has an impact on the engineering properties of bio-AAS materials. The study recommends correlating the percentage of free calcium ions within the AAS mixture with the microbial activity. Full article

Microbial mineralization of calcium–magnesium carbonate has been a hot research topic in the fields of geomicrobiology and engineering geology in the past decades. However, the formation and phase transition mechanism of calcium–magnesium carbonate polymorphs at different Mg/Ca ratios still need to be explored. In this study, microbial induced carbonate mineralization experiments were carried out for 50 days in culture medium with Mg/Ca molar ratios of 0, 1.5, and 3 under the action of Curvibacter sp. HJ-1. The roles of bacteria and the Mg/Ca ratio on the mineral formation and phase transition were investigated. Experimental results show that (1) strain HJ-1 could induce vaterite, aragonite, and magnesium calcite formation in culture media with different Mg/Ca molar ratios. The increased stability of the metastable phase suggests that bacterial extracellular secretions and Mg²⁺ ions inhibit the carbonate phase-transition process. (2) The morphology of bacteriological carbonate minerals and the formation mechanism of spherical minerals were different in Mg-free and Mg-containing media. (3) The increased Mg/Ca ratio in the culture medium has an influence on the formation and transformation of calcium–magnesium carbonate by controlling the metabolism of Curvibacter sp. HJ-1 and the activity of bacterial secretion. Full article

Antibacterial hydrogel wound dressings hold great potential in eliminating bacteria and accelerating the healing process. However, it remains a challenge to fabricate hydrogel wound dressings that simultaneously exhibit excellent mechanical and photothermal antibacterial properties. Here we report the development of polydopamine-functionalized graphene oxide (rGO@PDA)/calcium alginate (CA)/Polypyrrole (PPy) cotton fabric-reinforced hydrogels (abbreviated as rGO@PDA/CA/PPy FHs) for tackling bacterial infections. The mechanical properties of hydrogels were greatly enhanced by cotton fabric reinforcement and an interpenetrating structure, while excellent broad-spectrum photothermal antibacterial properties based on the photothermal effect were obtained by incorporating PPy and rGO@PDA. Results indicated that rGO@PDA/CA/PPy FHs exhibited superior tensile strength in both the warp (289 ± 62.1 N) and weft directions (142 ± 23.0 N), similarly to cotton fabric. By incorporating PPy and rGO@PDA, the swelling ratio was significantly decreased from 673.5% to 236.6%, while photothermal conversion performance was significantly enhanced with a temperature elevated to 45.0 °C. Due to the synergistic photothermal properties of rGO@PDA and PPy, rGO@PDA/CA/PPy FHs exhibited excellent bacteria-eliminating efficiency for S. aureus (0.57%) and E. coli (3.58%) after exposure to NIR for 20 min. We believe that the design of fabric-reinforced hydrogels could serve as a guideline for developing hydrogel wound dressings with improved mechanical properties and broad-spectrum photothermal antibacterial properties for infected-wound treatment. Full article

Calcium phosphate (CaP) particles immobilizing antibacterial agents have the potential to be used as dental disinfectants. In this study, we fabricated CaP particles with immobilized ciprofloxacin (CF), a commonly prescribed antibacterial agent, via a coprecipitation process using a supersaturated CaP solution. As the aging time in the coprecipitation process increased from 2 to 24 h, the CaP phase in the resulting particles transformed from amorphous to low-crystalline hydroxyapatite, and their Ca/P elemental ratio, yield, and CF content increased. Despite the higher CF content, the particles aged for 24 h displayed a slower release of CF in a physiological salt solution, most likely owing to their crystallized matrix (less soluble hydroxyapatite), than those aged for 2 h, whose matrix was amorphous CaP. Both particles exhibited antibacterial and antibiofilm activities along with an acid-neutralizing effect against the major oral bacteria, Streptococcus mutans, Porphyromonas gingivalis, and Actinomyces naeslundii, in a dose-dependent manner, although their dose–response relationship was slightly different. The aging time in the coprecipitation process was identified as a governing factor affecting the physicochemical properties of the resulting CF-immobilized CaP particles and their functionality as a dental disinfectant. Full article

In recent years, polyelectrolytes have been successfully used as an alternative to non-collagenous proteins to promote interfibrillar biomineralization, to reproduce the spatial intercalation of mineral phases among collagen fibrils, and to design bioinspired scaffolds for hard tissue regeneration. Herein, hybrid nanofibers were fabricated via electrospinning, by using a mixture of Poly ɛ-caprolactone (PCL) and cationic cellulose derivatives, i.e., cellulose-bearing imidazolium tosylate (CIMD). The obtained fibers were self-assembled with Sodium Alginate (SA) by polyelectrolyte interactions with CIMD onto the fiber surface and, then, treated with simulated body fluid (SBF) to promote the precipitation of calcium phosphate (CaP) deposits. FTIR analysis confirmed the presence of SA and CaP, while SEM equipped with EDX analysis mapped the calcium phosphate constituent elements, estimating an average Ca/P ratio of about 1.33—falling in the range of biological apatites. Moreover, in vitro studies have confirmed the good response of mesenchymal cells (hMSCs) on biomineralized samples, since day 3, with a significant improvement in the presence of SA, due to the interaction of SA with CaP deposits. More interestingly, after a decay of metabolic activity on day 7, a relevant increase in cell proliferation can be recognized, in agreement with the beginning of the differentiation phase, confirmed by ALP results. Antibacterial tests performed by using different bacteria populations confirmed that nanofibers with an SA-CIMD complex show an optimal inhibitory response against S. mutans, S. aureus, and E. coli, with no significant decay due to the effect of CaP, in comparison with non-biomineralized controls. All these data suggest a promising use of these biomineralized fibers as bioinspired membranes with efficient antimicrobial and osteoconductive cues suitable to support bone healing/regeneration. Full article

To explore the effects of the introduction order of calcium sources and the bacteria-to-calcium ratio on the microbially induced calcium carbonate precipitation (MICP) product CaCO₃ and to achieve the regulation of CaCO₃ crystal morphology, the mineralisation products of MICP were compared after combining bacteria and calcium at ratios of 1/9, 2/9, 3/9, 4/9, 5/9, and 6/9. A bacterial solution was combined with a urea solution in two calcium addition modes: calcium-first and calcium-later modes. Finally, under the calcium-first addition method, the output of high-purity vaterite-type CaCO₃ was achieved at bacteria-to-calcium ratios of 2/9 and 3/9; under the calcium-later addition method, the output of calcite-type CaCO₃ could be stabilised, and the change in the bacteria-to-calcium ratio did not have much effect on its crystalline shape. Full article