Microbial Reduction Research Articles

Evaluation of the efficacy of sonic activation in root canal cleaning with an endocator adenosine triphosphate tester: An in vitro study

Abstract Context: Evaluating the efficacy of sonic activation in root canal cleaning using an Endocator adenosine triphosphate (ATP) tester. Aim: The aim of this study was to assess the cleaning efficacy of needle irrigation and sonic activation by measuring ATP values and colony-forming units (CFUs) during root canal procedure. Settings and Design: The design of the study is an in vitro study. Materials and Methods: Eighty (n = 80) extracted mandibular molars were selected, and distal root canals were enlarged to F2 with ProTaper Gold rotary files. Canals were rinsed with 2 mL of 5.25% sodium hypochlorite (NaOCl), 2 mL of 17% ethylenediaminetetraacetic acid, and 2 mL of distilled water. Samples are sterilized, Enterococcus faecalis is inoculated and incubated at 37° for 4 weeks. Baseline ATP values and CFU are measured. Samples are divided into four groups of n = 20 and are irrigated. Group 1:2 mL of distilled water for 30 s. Group 2: 2 mL of distilled water activated with SmartLite Pro EndoActivator (SLP-EA) for 30 s. Group 3: 2 mL of 1% NaOCl for 30 s. Group 4: 2 mL of 1% NaOCl activated with SLP-EA for 30 s. The irrigation procedure was repeated for nine cycles. ATP values and CFU are recorded after each cycle. Friedman, Kruskal–Wallis, Wilcoxon, and Tukey’s post hoc tests are used for statistical evaluation. Results: A significant decrease in ATP values and CFU from baseline to residual level is observed in all groups (P ≤ 0.05). Microbial load reduction is significant in Group 4, followed by Groups 2 and 3. Conclusions: 1% NaOCl + SLP-EA showed better efficacy by recording lower ATP values and CFU.

Size-Dependent Reduction Kinetics of Iron Oxides in Single and Mixed Mineral Systems.

Iron(III) (oxyhydr)oxide minerals with varying particle sizes commonly coexist in natural environments and are susceptible to both chemical and microbial reduction, affecting the fate and mobility of trace elements, nutrients, and pollutants. The size-dependent reduction behavior of iron (oxyhydr)oxides in single and mixed mineral systems remains poorly understood. In this study, we used microbial and mediated electrochemical reduction approaches to investigate the reduction kinetics and extents of goethite and hematite. We found that small particles were preferentially reduced relative to their large counterparts in single and mixed mineral systems regardless of microbial or electrochemical treatments, which is attributed to the combined effect of higher thermodynamic favorability and greater surface availability. In mixed mineral systems, small particles were reduced slightly faster, whereas large particles were reduced notably slower and less extensively than solely predicted from single mineral systems. Specifically, when reduced alone, small particles showed Fe(III) reduction rate constants that were 1.5- to 3.6-fold higher than large particles, while when reduced together, the reduction rate constants for small particles were 6- to 21-fold higher than the rate constants for large particles. These collective findings provide new insights into the pivotal role of nanoparticulate iron (oxyhydr)oxides in environmental redox reactions.

Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models

Iron (Fe) reduction is one of the oldest microbial processes on Earth. After the atmosphere and ocean became oxygenated, this anaerobic process was relegated to niche anoxic environments. However, evidence of Fe reduction in oxic, partially saturated subsurface systems, such as soils and vadose zones, has been reported, with the common explanation being the formation of anoxic microsites that remain undetected by bulk measurements. To explore how microscale oxygen concentrations regulate microbial Fe reduction, we cultivated a facultative Fe-reducing bacterium using a microfluidic setup integrated with transparent planar oxygen sensors. Contrary to expectations, Fe reduction occurred under fully oxic conditions, without the formation of anoxic microsites. Our results suggest that microbially mediated Fe-reduction could be more widespread in oxic subsurface environments than previously assumed. Moreover, our mathematical modeling of oxygen dynamics around biomass-rich layers revealed that the onset of anoxia is mainly controlled by biomass spatial organization rather than the conventionally used water saturation index. This opens a new perspective on the proxies needed to predict anoxic microsite formation and Fe(III) reduction occurrence.

Heating-Induced Redox Property Dynamics of Peat Soil Dissolved Organic Matter in a Simulated Peat Fire: Electron Exchange Capacity and Molecular Characteristics.

Peatlands store one-third of the world's soil organic carbon. Globally increased fires altered peat soil organic matter chemistry, yet the redox property and molecular dynamics of peat-dissolved organic matter (PDOM) during fires remain poorly characterized, limiting our understanding of postfire biogeochemical processes. Clarifying these dynamic changes is essential for effective peatland fire management. This study demonstrates temperature-dependent dynamic changes in the electron exchange capacity (EEC) of PDOM by simulating peat soil burning, significantly affecting microbial iron reduction. At low fire temperatures (200-250 °C), the EEC remains constant by releasing more phenolic moieties to enhance the electron-donating capacity (EDC). Higher temperatures (500 °C) diminish 90% of the EEC by consuming phenolic-quinone moieties. Pyrolytic PDOM (pyPDOM) contributes to 40% of the EEC of peat soil, with this contribution declining at higher temperatures. Phenolic-quinone moieties remain the primary redox-active moieties in pyPDOM. Fourier transform ion cyclotron resonance mass spectrometry analysis shows that postfire EDC depends more on phenolic types than abundance, with monophenol-like molecules (C < 12) being more significant than polyphenol-like (C ≥ 12). Quinone moieties in pyPDOM are associated with high-oxygen condensed aromatics, and their depletion reduces the electron-accepting capacity, weakening its electron shuttle effect in microbial iron reduction. Our findings enhance the understanding of the changes in PDOM redox properties during fires.

Microbial sulfate reduction regulated by relative sea level change in a Pleistocene – Holocene sedimentary record: Insights from Loch Duart, Scotland, UK

Microbial sulfate reduction regulated by relative sea level change in a Pleistocene – Holocene sedimentary record: Insights from Loch Duart, Scotland, UK

Control mechanism of Escherichia coli invasion by micro-nano bubbles in drinking water distribution system.

Sudden biological contamination in Drinking Water Distribution System (DWDS) significantly threatens the safety of drinking water, with E. coli invasions being particularly hazardous to human health. Traditional disinfection methods (i.e., chlorine, ultraviolet and ozone) provide partial microbial reduction. Micro-nano bubbles (MNBs) offer a promising alternative due to easy preparation, environmental friendliness, and generating ·OH in situ. This study explored the control mechanism of MNBs using different gas sources (i.e., nitrogen, air, oxygen, and ozone) on E. coli invasion in drinking water of the secondary water supply tanks. MNB characteristics, water quality changes, bacterial concentration, and microbial communities were evaluated. Results indicated that E. coli gradually became the dominant bacterium by promoting species interaction and influencing the process of microbial community construction, leading to a 6.25% increase in bacterial counts in water. MNBs generated via a dissolved gas release method exhibited particle sizes ranging from 500 to 800 nm and Zeta of -0.6 to -3.1 mV, and the bubble collapse effect generated a large amount of ·OH (0.11 ∼ 0.40mmol/L), which reduced bacterial abundance by 66.53% and microbial community richness, as revealed by decreases in the Chao (10.53%) and ACE (3.75%) indexes. The oxidative stress induced by ·OH inhibited protein transcription and energy production, which damaged DNA repair mechanisms. Thus, the relative abundance of Gammaproteobacteria, including E. coli as the dominant strain, decreased by 47.6%, leading to a balanced microbial community. Additionally, MNBs showed a complete reduction of bacteria, such as Caldisericia and Fusobacteria, thereby improving the drinking water safety and biological stability. This study highlights the potential of MNBs to address sudden exogenous biological pollution in DWDS, providing critical theoretical support to ensure the safety of drinking water quality.

Insights into the enhanced uranium reduction efficiency through extracellular polymeric substances from Desulfovibrio vulgaris UR1 induced by mediating materials.

Understanding the role of extracellular polymeric substances (EPS) in the microbial reduction of uranium accelerated by mediating materials is crucial for enhancing the bioremediation of uranium-contaminated wastewater. In this study, biochar- and magnetite-loaded Desulfovibrio vulgaris UR1 exhibited significantly higher uranium reduction efficiency, with increases of 1.52 and 1.44 times respectively within one day. After loading with mediating materials, the charge transfer resistance of EPS was reduced, facilitating the extracellular electron transfer process. The increase of redox components, such as aromatic compounds and flavins, in EPS explained the enhanced extracellular electron transfer capacity. Moreover, the higher α-helix content in extracellular proteins could promote electron hopping. Proteomics analysis showed that extracellular proteins involved in iron-sulfur cluster binding, oxidoreductase activity, and electron transfer were significantly up-regulated, which facilitated the rapid microbial reduction of uranium. These findings provide valuable insights into the in-depth development of bioremediation technology for uranium-contaminated wastewater.

Comparison of Filtration Processes Using Microfiltration, Ultrafiltration, Nanofiltration and Reverse Osmosis Methods on The Characteristics of Lemon Juice Functional Beverages At Pilot Scale

This study aims to determine the comparison of filtration processes using filtration membranes which include Microfiltration, Ultrafiltration, Nanofiltration and Reverse Osmosis on the characteristics of lemon juice functional drinks on a pilot scale, so that the stability of product results from the four different methods can be known. The best product quality parameters in this study include vitamin C content, total acid content, total soluble solids content, antioxidant activity, pH value, viscosity value, *b value (yellowish color), total microbial reduction, and hedonic quality test (aroma, taste, and aftertaste). So that a comparison of product characteristics can be obtained. The research conducted will go through three stages including the manufacture of control juice products as a comparison, the characteristics of products processed using membrane filtration machines and data processing using t tests conducted to find a comparison of the results of these products.The results of this study are the manufacture of lemon juice functional beverages using the filtration membrane method affects the vitamin C content, total acid content, total dissolved solids and antioxidant activity because the pore size of the membrane will decrease and the particles contained in the sample will be increasingly filtered and after being compared between each method, the highest results are obtained in the microfiltration method and the lowest is reverse osmosis. The manufacture of lemon juice functional beverages using the filtration membrane method affects the pH value, viscosity and color because the pore size of the microfiltration membrane to reverse osmosis is getting smaller so that it will decrease the pH value, viscosity and color. The manufacture of lemon juice functional beverages using the filtration membrane method affects the quality of the product, where in organoleptic testing the color attributes of the MF method produce lemon yellow beverage products. At the aroma attribute, the UF method produces a typical lemon-scented beverage product. At the taste attribute, the RO method produces a very sour beverage product typical of lemon. At the aftertaste attribute, the MF method produces very bitter beverage products.

Influences of fluctuating nutrient loadings on nitrate-reducing microorganisms in rivers.

Rivers serve important functions for human society and are significantly impacted by anthropogenic nutrient inputs (e.g. organic and sulfur compounds). Reduced organic and sulfur compounds influence the nitrogen cycle as they are electron donors of microbial nitrate reduction. Water pollution caused by individual nutrients and the mechanisms have been studied, but how the variation in multiple nutrient loadings influences nitrate-reducing microorganisms is less understood. Two sets of microcosms were established and exposed to nitrate, along with either acetate or thiosulfate, at different times. Nutrient concentrations responded to the loading pollutant. The nutrient loading order was more important in shaping microbial community structure and microbial interactions through the exchange of growth-required substances. This indicated that upstream or historical nutrient inflows impacted current nitrate reduction by changing the seeding microbial community, highlighting the importance of river connectivity. Based on metatranscriptome analysis, although the order and type of nutrient loadings were equally important in regulating global transcriptomes, transcripts of enzymes for key metabolisms (nitrate reduction, sulfur oxidation, etc.) more actively responded to the nutrient type. The regulation of a small set of genes was sufficient to make the transition, while most transcripts were not degraded and regenerated. These insights are important for understanding the varying pollution status of rivers and for developing effective solutions, such as remediation.

Efficacy of antimicrobial photodynamic therapy in endodontics of primary teeth: a scoping review.

The objective of this study was to identify, describe and synthesize the data published about the effectiveness of antimicrobial photodynamic therapy (aPDT) in the pulpectomy of primary teeth. A search was conducted in six electronic databases and the gray literature in June and July 2023, without restrictions on language or date of publication. The search strategy included indexed terms (MeSH terms) and your synonyms. Clinical trials, in vitro studies, case reports and retrospective studies that used photodynamic therapy in primary teeth pulpectomies were considered eligible. Among the 1,674 articles retrieved, 15 were included, published between 2014 and 2022, comprising six in vitro studies, five clinical trials, and four case reports. The sample consisted of children aged 2 to 8 years of both sexes, and included 1 to 62 teeth, mostly anterior. In two in vitro studies, the sample was taken from root canals. Most studies used a diode laser, methylene blue, and optical fiber. The pre-irradiation time ranged from 1 to 5min. All protocols demonstrated microbial reduction before and after using aPDT, with no statistical difference among the groups. Furthermore, six studies demonstrated treatment success. Despite the divergence in methodology and protocols, aPDT is an effective method for reducing microorganisms, and is a promising adjunct treatment in primary teeth pulpectomies.

Osmosonication parameters affect Salmonella Typhimurium and Lactobacillus rhamnosus reductions in solutions and fruit juices

Introduction. Sonication followed by storage in high osmotic pressure, referred to as osmosonication, can significantly reduce microbial loads in food products. Understanding the parameters that influence these reductions is essential. Objective. To evaluate the effect of osmosonication parameters on the reduction of Salmonella Typhimurium and Lactobacillus rhamnosus in model solutions and fruit juices. Materials and methods. This study was conducted at the Universidad de Costa Rica, San José, Costa Rica between January and December 2012. Completely randomized experiments were designed for both model solutions and fruit juices, with data analyzed using ANOVA. The parameters evaluated included amplitude (20, 25, 30, 35, and 40 %), sonication time (10, 20, and 30 minutes), percentage of pulsations time (90, 50, 10, and 0), pectin content (0, 0.5, and 1,0 %), and cellulose content (0, 0.15, and 0.30 %), pH (2.5; 3.5; 4.5; 5.5, and 6.5) or natural juice pulp content. Results. L. rhamnosus demonstrated greater resistant to osmosonication treatments compared to S. Typhimurium. Microbial reductions increased with higher sonication times and amplitudes. The percentage of pulsations time did not significantly influence bacterial reductions. Lower pH values resulted in reduced bacterial resistance to osmosonication. Neither pectin nor cellulose content significantly affected the resistance of either microorganism to osmosonication. Similar treatments applied to fruit juices (blackberry, pineapple, apple, and coconut water) showed that microbial reductions for both bacteria were influenced by the type of juice, likely due to varying pH levels. These effects was also bacteria-dependent. Pulp content affected bacterial resistance to osmosonication, with the impact varying by bacterial species. Conclusions. Osmosonication parameters such as amplitude, time, pH, and the pulp content influence the reduction of Salmonella Typhimurium and Lactobacillus rhamnosus in model solutions and fruit juices.

Efficacy of Antimicrobial Dry Fog in Improving the Environmental Microbial Burden in an Inpatient Ward.

Background/Objectives: In healthcare environments with high microbial loads, effective infection control measures are critical for reducing airborne and surface contamination. One of the novel modalities in the achievement of these goals is the use of antimicrobial mists, such as droplets, in the form of dry fog. Although the usage of dry fog in the disinfection of contained healthcare microenvironments is well known, the effect of such a system in terms of a meaningful reduction in the microbial burden in an open inpatient ward is unclear. Our objective was to assess the impact of scheduled dry fogging on microbial reduction in such settings. Methods: We collected air and surface samples from rooms receiving daily, biweekly, or no fogging (controls) over six months, establishing the baseline contamination and evaluating the reduction trends in treated rooms. The "reduction effect" was measured by tracking microbial isolation trends before and after treatment, while the "degree of reduction" assessed differences across rooms with varied disinfection schedules. Results: The results indicate that scheduled dry fogging significantly reduced microbial loads in treated rooms, especially with daily disinfection (SE = 64.484, p = 0.002). The airborne contamination in treated rooms showed a strong downward trend over time (SE = 19.192, p < 0.001). Surface contamination remained challenging due to frequent recontamination; however, treated rooms exhibited a consistent reduction in microbial presence (SE = 2.002, p = 0.010), confirming dry fogging's role as a valuable adjunct to routine cleaning. Conclusions: In conclusion, this study highlights that dry fogging effectively reduces microbial loads in open, high-traffic healthcare environments, supporting its use as part of a multimodal infection control strategy.

Nitrous oxide is the main product during nitrate reduction by a novel lithoautotrophic iron(II)-oxidizing culture from an organic-rich paddy soil.

Microbial nitrate reduction coupled to iron(II) oxidation (NRFeOx) occurs in paddy soils due to high levels of dissolved iron(II) and regular application of nitrogen fertilizer. However, to date, there is no lithoautotrophic NRFeOx isolate or enrichment culture available from this soil environment. Thus, resulting impacts on greenhouse gas emissions during nitrate reduction (i.e., nitrous oxide [N2O]) and on toxic metalloid (i.e., arsenic) mobility can hardly be investigated. We enriched a lithoautotrophic NRFeOx culture, culture HP (Huilongpu paddy, named after its origin), from a paddy soil (Huilongpu Town, China), which was dominated by Gallionella (71%). The culture reduced 0.45 to 0.63 mM nitrate and oxidized 1.76 to 2.31 mM iron(II) within 4 days leading to N2O as the main N-product (62%-88% N2O-N of total reduced NO3--N). Nitrite was present as an intermediate at a maximum of 0.16 ± 0.1 mM. Cells were associated with, but mostly not encrusted by, poorly crystalline iron(III) minerals (ferrihydrite). Culture HP performed best below an iron(II) threshold of 2.5-3.5 mM and in a pH range of 6.50-7.05. In the presence of 100 µM arsenite, only 0%-18% of iron(II) was oxidized. Due to low iron(II) oxidation, arsenite was not immobilized. However, the proportion of N2O-N of total reduced NO3--N decreased from 77% to 30%. Our results indicate that lithoautotrophic NRFeOx occurs even in organic-rich paddy soils, resulting in denitrification and subsequent N2O emissions. The obtained novel enrichment culture allows us to study the impact of lithoautotrophic NRFeOx on arsenic mobility and N2O emissions in paddy soils.IMPORTANCEPaddy soils are naturally rich in iron(II) and regularly experience nitrogen inputs due to fertilization. Nitrogen fertilization increases nitrous oxide emissions as it is an intermediate product during nitrate reduction. Microorganisms can live using nitrate and iron(II) as electron acceptor and donor, respectively, but mostly require an organic co-substrate. By contrast, microorganisms that only rely on nitrate, iron(II), and CO2 could inhabit carbon-limited ecological niches. So far, no isolate or consortium of lithoautotrophic iron(II)-oxidizing, nitrate-reducing microorganisms has been obtained from paddy soil. Here, we describe a lithoautotrophic enrichment culture, dominated by a typical iron(II)-oxidizer (Gallionella), that oxidized iron(II) and reduced nitrate to nitrous oxide, negatively impacting greenhouse gas dynamics. High arsenic concentrations were toxic to the culture but decreased the proportion of nitrous oxide of the total reduced nitrate. Our results suggest that autotrophic nitrate reduction coupled with iron(II) oxidation is a relevant, previously overlooked process in paddy soils.

A Meta-Analysis on the Antimicrobial Effectiveness of Ozonated Water Treatments for Fresh Produce Washing-Effect of Ozonation Methods.

Due to the lack of a pathogen-killing process, foodborne outbreaks from contaminated fresh produce have been increasing worldwide. Hence, it is increasingly recognized that the washing step with sanitizers is important to control microbial contamination. Ozonated water is suggested as a substitute for chlorine-based sanitizers, addressing concerns about the effectiveness and environmental impact of chlorine-based sanitizers. However, using ozone as a sanitizer in the fresh produce washing process is still challenging because of its unstable and inconsistent antimicrobial effectiveness under various testing conditions. A meta-analysis was focused on the comparison of antimicrobial effectiveness between different ozonation methods commonly adopted in laboratory settings, including stationary pre-ozonated water, agitated pre-ozonated water, and sparging. The meta-analysis showed that the sparging method results in the highest microbial log reduction compared to other methods. We further developed meta-regression models based on three ozonation methods to identify key processing variables influencing the antimicrobial effectiveness of ozonated water. Attempts were made to link key processing variables to ozone stability and the mass transport phenomena involved in the washing process. This research will contribute to designing and developing a washing process to increase fresh produce safety by identifying key factors in each ozonation method and facilitate interlaboratory comparison studies.

Dentition Type as a Determinant of Microbial Load Reduction by Antimicrobial Photodynamic Therapy in Deep Dentin Caries: A Systematic Review and Meta-analysis.

Antimicrobial photodynamic therapy (aPDT) is a protocol proposed for reduction of bacterial load in deep dentin caries in primary and permanent dentitions. However, considering the difference in the morphology of dentinal tubules in primary and permanent teeth, the effect of this treatment may be different on the two dentition types. This systematic review and meta-analysis aimed to assess the effect of type of dentition as a determinant of microbial load reduction by aPDT in deep dentin caries. An electronic search was conducted in Scopus, Web of Science, Cochrane, Medline, and Embase databases, from the first record until April 30, 2022. After article screening by three reviewers, seven studies were included in this meta-analysis. The mean log of Streptococcus mutans (S. mutans) count, Lactobacillus spp. count, and the entire bacteria in the cavity before and after aPDT was calculated with 95% confidence interval (CI), and compared between the two groups of primary and permanent teeth by the random effect model. The I2 test was applied to assess the heterogeneity of the findings. Publication bias was evaluated by visual examination of the funnel-plot symmetry. Of 7 retrieved articles, analysis of 3 studies on permanent teeth showed that aPDT caused a significant reduction in total bacterial count in the cavity [SMD: 0.64, 95% CI:(0.31, 0.96), p= 0.0001), S. mutans count [SMD: 0.92, 95% CI:(0.58, 1.25), p< 0.0001], and Lactobacillus spp. [SMD: 1.1, 95% CI:(0.76, 1.45), p< 0.00001)]. Analysis of the remaining 4 studies on primary teeth indicated that aPDT had a significant effect only on S. mutans count [SMD: 0.60, 95% CI:(0.23, 0.97), p= 0.001), and its effect on total bacterial count of the cavity [SMD: 0. 90, 95% CI:(-0.02, 1.82), p= 0.05] and Lactobacillus spp. [SMD: 0.18, 95% CI:(-0.29, 0.64), p= 0.45)] was not significant. The results showed that aPDT could serve as an effective adjunct for reduction of microbial load in permanent teeth.

Comparative Evaluation of Novel Automated Irrigation Devices with Side-Vented Needle Irrigation on Bacterial CFU Counts in Nonvital Teeth

ABSTRACT Background: Syringe needle irrigation is used frequently to deliver root canal disinfectants. However, conventional syringe needle irrigation has its potential drawbacks. The current study, hence, aimed at assessing the real-time benefit of using conventional needle irrigation as compared to a novel automated irrigation device in patients undergoing root canal treatment. Methods: It is a prospective study where 45 patients with single-rooted teeth were allocated into three groups according to the respective test disinfection technique used for disinfection: group I: novel automated irrigation device, group II: open-ended flat needle irrigation, and group III: side-vented needle irrigation. Pre- and postoperative culture samples were obtained and transferred immediately for microbial analysis. Results: A difference was noted among the groups (P &lt; 0.05) in the antimicrobial efficacy of aerobic and anaerobic bacteria. Conclusion: The novel automated irrigation device was better than syringe needle irrigation in microbial reduction.

First microscale data on depth profiles of microbial N₂O reduction, O2 availability, and pore networks inside contrasting single soil aggregates

First microscale data on depth profiles of microbial N₂O reduction, O2 availability, and pore networks inside contrasting single soil aggregates

Control of arsenic methylation in paddy soils by iron nanoparticles

Rice, as the most essential food grain, is frequently exposed to high concentrations of arsenic. Among the arsenic species, dimethylarsenate (DMAs(V)) is preferentially translocated from paddy soils to rice grains, posing serious threats to food safety and yield. Herein, we report an efficient strategy for DMAs(V) mitigation in paddy soils with nanoscale Zero-Valent Iron (nZVI). Species and concentrations of arsenic in paddy porewater were monitored during a 28-d soil-water incubation. Effects of nZVI dose towards microbial sulfate reduction and methane generation potential in paddy soils, which are crucial for arsenic methylation and demethylation, were analyzed via metagenomic sequencing. Results demonstrated that the maximal DMAs(V) concentration in paddy porewater decreased from 0.37 to 0.04 μM in arsenic-contaminated paddy soils with nZVI dose increasing from 0 to 5.0 g/kg. Accordingly, the maximal concentration of inorganic arsenite (iAs(III)), which is the precursor of DMAs(V), decreased from 1.39 to 0.23 μM. Furthermore, the application of nZVI reshaped the structure of microbial community in paddy soils. Specifically, the relative abundance of δ-proteobacteria involved in sulfate reduction, which is crucial for iAs(III) methylation, waned from 7.62 % to 3.17 %, while that of Methanomicrobia for DMAs(V) demethylation and methanogenesis proliferated from 7.03 % to 13.62 %, with nZVI dose increasing from 0 to 5.0 g/kg. Via simultaneous inhibition of DMAs(V) formation and acceleration of DMAs(V) transformation, nZVI efficiently controls the accumulation of DMAs(V) in paddy porewater. In conclusion, these findings prove the efficient performance for DMAs(V) mitigation with nZVI and uncover its underlying mechanisms.

Investigating the effect of combined radiofrequency cold plasma (RF-CP) treatment on techno-functional attributes of Cashewnut

In the realm of food safety, dried foods often find themselves on the favourable side of the risk spectrum, enjoying the reputation of being relatively safer. However, dried food products are reportedly contaminated by microorganism beyond permissible limits, thus, depleting their quality, shelf-life, etc. and pose a threat to the consumers. This study aims to explore the effect of radiofrequency low-pressure cold plasma (RF-CP) processing on cashew nuts, using four gas combinations: Nitrogen (N2), Argon (Ar), N2+O2, and Ar+O2. Dried cashew nut kernels underwent RF-CP treatment at six different power options (60, 90, 120, 150, 180, and 210 W), at four distinct time (5, 10, 15, and 20 min). Following the treatment, the samples underwent proximate analysis, microbial load reduction, sensory analysis, peroxide value, and texture analysis. The findings exhibited a direct relationship between plasma power and treatment duration, indicating that an escalation in both parameters induced proportional enhancement in the reduction rate of microbes, with a maximum reduction of over 99% in total plate count, yeast and mould count at 120 W for 20 min and 150 W for 15 min for N2+O2 and Ar+O2 gas combinations, respectively. No statistically significant difference was observed in the sensory, nutritional, and peroxide value between the treated and untreated samples (p > 0.05). However, the moisture content of treated sample decreased, and firmness increased with an increase of power and RF-CP exposure time. This research demonstrates the feasibility of using RF-CP to decontaminate cashews by inactivating microbes, extending shelf life, and altering surface properties, which may enhance texture and appearance. However, it may also induce oxidative changes in lipids and proteins, potentially affecting flavor, nutritional quality, and allergenicity. It is an emerging and alternative to high-temperature processing for disinfecting products like nuts, spices, aromatic plants, and other delicate and luxurious foods.

Extracellular electron transfer-dependent bioremediation of uranium-contaminated groundwater: Advancements and challenges.

Efficient and sustainable remediation of uranium-contaminated groundwater is critical for groundwater safety and the sustainable development of nuclear energy, particularly in the context of global carbon neutrality goals. This review explores the potential of microbial reduction processes that utilize extracellular electron transfer (EET) to convert soluble uranium (U(VI)) into its insoluble form (U(IV)), presenting a promising approach to groundwater remediation. The review first outlines the key processes and factors influencing the effectiveness of dissimilatory metal-reducing bacteria (DMRB), such as Geobacter and Shewanella, during uranium bioremediation and recovery. The cutting-edge progress on the molecular mechanism of EET-driven U(VI) reduction mediated by c-type cytochromes, conductive pili, and electron mediators, is critically reviewed. Additionally, advanced strategies such as optimizing electron transfer, leveraging synthetic biology approach, and integration with machine learning are discussed to enhance the efficiency of EET-driven processes. The review also considers the integration of EET processes into practical engineering applications, highlighting the need for optimization and innovation in bioremediation technologies. By providing a comprehensive overview of current progress and challenges, this review aims to inspire novel research and practical advancements in the field of uranium-contaminated groundwater remediation.