Mineral Water Research Articles

Chrysin alleviates salt stress in tomato by physiological, biochemical, and genetic mechanisms

Soil salinity greatly reduces agricultural productivity, especially in dry and semi-arid regions, by interfering with physiological and biochemical processes. This research aimed to determine whether Chrysin (Chr) can mitigate the negative effects of salinity on growth parameters, antioxidant enzyme activity, and gene expression in tomato (Solanum lycopersicum L.) plants. Experiments were conducted in a semi-controlled greenhouse, with plants subjected to varying concentrations of sodium chloride (NaCl) (0 and 100 mM) and Chr (0, 0.1, 0.5, and 1.0 mM). Results revealed that salinity stress significantly reduced plant height, leaf area, and chlorophyll content while increasing hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline levels, indicating oxidative stress. Chr application alleviated these detrimental effects by enhancing the activity of antioxidant enzymes such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), thereby reducing reactive oxygen species (ROS) accumulation. Additionally, Chr treatments improved plant water status and mineral content under salt stress. Gene expression analysis showed that Chr positively regulated the transcription of salt tolerance-related genes, including HKT1-1, HKT1-2, and PIP1-2, which are associated with sodium ion transport and water balance. These findings suggest that Chr can be an effective biostimulant for enhancing salt tolerance in tomato plants by modulating physiological, biochemical, and genetic mechanisms. This study provides insights into Chr's potential as a sustainable solution for improving crop resilience to salinity in agricultural practices. Further research is recommended to optimize Chr concentrations for maximum efficacy.

Effectiveness of cocoa bean extract mouthwash against gingivitis in pregnant women in Aceh Besar

Background: Gingivitis and periodontitis are the most common dental support tissue problems in dentistry. Gingivitis is an inflammation of the gingiva due to the body's response to the accumulation of dental plaque bacteria in the form of Streptococcus mutans, Streptococcus sanguis, Actinomyces, and Spirochaeta on the surface of the teeth. Gingivitis and nutritional status in pregnant women are related to the risk of 8.75 times the birth of low-birth-weight babies (BBLR) and premature babies. Prevention of gingivitis can be done chemically through gargling with antibacterial mouthwash. Therefore, herbal ingredients are needed that can prevent plaque and control gingivitis. This study aims to determine the effectiveness of mouthwash of cocoa bean extract against gingivitis. Methods: This study used the post-test only control group design method. The study was conducted on pregnant women in Bayu Aceh Besar village with a total of 30 samples. The sample was divided into 3 groups that received different treatments. Group 1 was instructed to do a mouthwash with cocoa extract mouthwash while Group 2 with chlorhexidine, group 3 with mineral water. Each pregnant woman gargles for 30 seconds (20 ml) for 3 days. Results: Analysis of the gingival index before and after using cocoa seed extract mouthwash showed that this mouthwash was more effective in reducing the gingival index with a value of p=0.012 (p<0.05). Conclusions: Gargling with cocoa bean extract is more effective in reducing gingivitis. We recommend further studies to investigate the potential of cocoa bean extract for use in mouthwashes.

Strategi Pemasaran Air Minum dalam Kemasan di Pondok Pesantren Riyadhus Samawi

In general, some of the community's drinking water needs can be sourced from well water and water that has been treated by the Regional Drinking Water Company (PDAM). However, the increasing demand for drinking water sometimes cannot be met by well water sources or water that has been treated by PDAM. Along with technological advances, accompanied by increasingly busy community activities today tend to choose a more practical way at a relatively low cost in meeting drinking water needs. One of the alternative ways to fulfill drinking water needs is by using mineral water products. Marketing is a process of preparing integrated communication that aims to provide information about goods or services in relation to human needs. The marketing carried out at the Riayadus Samawi Islamic Boarding School is still very simple, namely from word of mouth to the congregation. So that Yarisa Drinking Water has not been sold widely like bottled drinking water in general because the majority of consumers are still worshipers and the neighborhood around the cottage. The purpose of this community service is to contribute thoughts and training, especially to the manager of Yarisa drinking water regarding the importance of analyzing marketing strategies for a company in an effort to market its products so that these products can be accepted by the public and distributed widely. The PKM process carried out at the Riyadus Samawi Ludoyo Blitar Islamic Boarding School consists of three stages, including: first, problem identification with a study carried out by the PKM team, Yarisa drinking water managers, cottage administrators, cottage caregivers, and cottage owners to find out the quality and development of Yarisa drinking water marketing strategies. The second stage is the implementation of PKM by holding a seminar with the theme “Marketing Strategy for Bottled Drinking Water at Riyadus Samawi Islamic Boarding School” and attended by Yarisa drinking water managers and students and board members. The third stage is monitoring and evaluation of whether the bottled drinking water marketing strategy delivered by the PKM team has been implemented in Yarisa drinking water. The results of this PKM are socialization and assistance regarding bottled drinking water marketing strategies and making several marketing and motivational programs so that in the future Yarisa drinking water owned by Riyadus Samawi Islamic Boarding School can be marketed widely.

Quantitative analysis of sodium concentration in condiments, soft drinks and mineral water by external standard 23Na-qNMR.

Sodium is essential for human health, but excessive intake can lead to hypertension. Accurate sodium labeling in foods is critical due to increasing health awareness. This study investigated the use of 23Na nuclear magnetic resonance spectroscopy (NMR) for sodium quantification in condiments, soft drinks and mineral water. In this study, external standard quantitative 23Na-NMR was used to measure sodium concentrations. Key steps included sample preparation, 90° pulse width calibration, and linewidth evaluation. The results showed that 23Na-NMR can accurately quantify sodium concentrations over a wide range, with good agreement with ion electrode methods. The results demonstrated that 23Na-NMR is a reliable method for the quantification of sodium in various liquid foods.

Achieving Sustainability in the Management of Natural Resources Given to a Concession

The sustainable management of resources is part of the strategic objectives of the European economic policy for the transition from a linear to a circular economy. One of its aspects, at the national level, is the protection of deposits of underground wealth and mineral waters on the territory of the Republic of Bulgaria from depletion and improper exploitation. The purpose of the article is to present the main requirements for the users of this type of natural resources when granting concessions by the state, in order to determine whether there are mechanisms for achieving sustainability in their management. By studying the current legislation and analyzing data from the National Concession Register, the most frequently used practices for sustainable management of these valuable resources used for economic purposes are presented: establishment of environmental requirements; limiting the rights to extract and exploit the deposits to predetermined limits and volumes, for a certain period of time; requirements for preparation of work plans, reports and reporting documentation; delivery of the concession object in a condition suitable for subsequent operation; requirements for reclamation, enhanced administrative control, which covers the entire project cycle of realization of investments in the extraction of this type of resources, etc. As a result of the study, the article formulates recommendations for expanding the sustainability requirements and strengthening the control in their application. This will ensure a wider time horizon for their economic exploitation and will contribute to achieving one of the EU’s fundamental goals: to ensure suitable conditions for economic growth for future generations without resource dependence.

The relevance of biotic processes on modern tufa deposits, with an example from the Bonito region, Central-West Brazil

Abstract Tufas are freshwater carbonate rocks that form in continental environments through a combination of physical, chemical, and biological processes. This study investigates the role of microorganisms in the precipitation of Quaternary tufa deposits in the Serra da Bodoquena Formation, in the Bonito region. Two sites along the Mimoso River, named Taíka and Mimosa, characterized by the pool–barrage–cascade depositional subenvironment, were selected for this study. Four distinct facies were identified: stromatolitic boundstones, phytoherm boundstones of algae, phytoherm boundstones of bryophytes, and phytoclastic rudstones. These facies were observed in diverse hydrological settings, including fast-flowing waters, such as waterfalls and cascades, as well as slow-flowing areas, such as pools and dams. The δ18O depletion indicated a meteoric origin for the fluid involved in carbonate precipitation. The low δ13C values were attributed to photosynthetic processes and the contribution of light carbon-enriched groundwater. The presence of Oocardium stratum and calcified organic mucilage from extracellular polymeric substance (EPS) corroborates the significant role of microorganisms in tufa formation, particularly in stromatolitic boundstones and phytoherm boundstones of algae. Rapid CO2 degassing significantly contributes to mineralization in fast-flowing waters. Micro-CT results offer detailed insights into the relationship between mechanical processes and biological influences in shaping porosity characteristics. The findings of this study significantly enhance our understanding of the role of microorganisms in tufa formation, highlighting the complex interplay between biotic and abiotic processes in the development of different tufa facies. Moreover, the insights gained from this study provide valuable implications for interpreting tufa deposits worldwide.

Life Cycle Assessment of Extraction of Cellulose from Date Palm Biomass Using Natural Deep Eutectic Solvent (NaDES) via Microwave-Assisted Process

This study investigates the extraction of cellulose from Saudi Arabia-based date palm biomass utilizing a natural deep eutectic solvent (NaDES) integrated with a microwave-assisted process. A comprehensive life cycle assessment (LCA) was conducted in accordance with the ISO 14040 standard, encompassing four key stages: goal and scope definition, life cycle inventory analysis (LCI), life cycle impact assessment (LCIA) and interpretation. The analysis was confined to a gate-to-gate boundary in which two impact assessment methods, namely, ReCiPe Midpoint (H) 2016 and ILCD 2011 Midpoint, were used to assess the environmental impacts. The OpenLCA software (version 2.1.1) with the European Life Cycle Database 3.2 (ELCD 3.2) was used in the study. The ReCiPe method identified impact categories such as fossil resource scarcity, terrestrial ecotoxicity, freshwater ecotoxicity, water consumption, human carcinogenic toxicity and marine ecotoxicity. Conversely, the ILCD method identified freshwater ecotoxicity, water resource depletion, mineral, fossil and resource depletion, human toxicity and cancer effects. The results indicate that freshwater ecotoxicity presents the most substantial environmental impact across both assessment methods, surpassing other categories. Fossil resource scarcity, even though originally appearing impactful, demonstrated a relatively lower normalized score compared to freshwater ecotoxicity. Terrestrial ecotoxicity and water consumption were found to be negligible in their impact. Our findings provide important insights into sustainable material science and waste management, affording potential applications for biomass utilization in the Gulf region.

High-intensity pulse magnetic therapy and drinking mineral water in rehabilitation treatment of patients with chronic pancreatitis at inpatient stage

BACKGROUND: Sanogenetic effects of physical factors, providing restoration of disturbed functions of the organism, are the basis for their inclusion in the standardised programme of restorative treatment of patients with chronic pancreatitis. AIM: To study the effectiveness of high-intensity pulse magnetic therapy and low-mineralized drinking mineral waters in the restorative treatment of patients with chronic pancreatitis at the inpatient stage. MATERIALS AND METHODS: There has been carried out an open-label, randomized, controlled, prospective study of 125 patients with chronic pancreatitis. The patients were divided into 3 groups using the simple randomization method. In the control group (n=40) the patients underwent restorative treatment in accordance with federal clinical guidelines; in the group of comparison (n=42) he patients were additionally prescribed low-mineralized drinking mineral water; in the main group (n=43) the patients had high-intensity pulse magnetic therapy in addition to the treatment of the group of comparison. The effectiveness of rehabilitation measures was monitored using a visual analogue scale, a carbolene test, a hospital scale of anxiety and depression. RESULTS: The statistical analysis showed that the inclusion of drinking mineral water and high-intensity pulse magnetic therapy contributed to a significant reduction of pain (p 0.01) and dyspeptic syndromes (p 0.01), an improvement in motor evacuation function of intestine (p 0.01), a decrease in enzymatic activity and the severity of anxiety-depressive manifestations (p 0.01). The effectiveness of the developed programmes of restorative treatment of the patients suffering from chronic pancreatitis was 87.8–92.5%, the standardized programme ― 78.5%. CONCLUSION: The inclusion of drinking mineral waters and high-intensity pulse magnetic therapy in the standardized program of restorative treatment of the patients suffering from chronic pancreatitis at the inpatient stage provides a significant restoration of pancreatic external secretory function.

Does the karst spring improve fish abiotic habitat in mountain streams?

Mountain streams constitute challenging habitat for many fish species due to rapid and variable flow, cool temperature, and limited food resources. Groundwaters recharge by karst spring may however mitigate harsh habit conditions of mountain streams providing niches for different fish species. This study aims to assess the suitability of mountain streams, replenished by karst springs, for various fish species like alpine bullhead, European grayling, brown and brook trout. The study was conducted in the Chochołowski Stream in the Western Tatra Mountains, Poland. The assessment of abiotic habitat is based on different characteristics of hydrological and thermal regimes as well as water chemical composition investigated between 01.09.2012 and 31.09.2014. The findings reveal that: 1) downstream variability of habitat abiotic conditions (such as water temperature, flow, water chemical composition) may affect the distribution of fish species, 2) karst springs contribute up to 100% of the stream’s recharge during periods of winter low flow, 3) karstic groundwater reduces the variability and amplitudes of stream water temperature and weaken the periodicity in water temperature associated with daily course of air temperature and solar radiation, 4) groundwaters prevent stream freezing in winter and moderate summer temperatures, 5) increasing mineralisation of water below the spring recharge may positively affect fish distribution. The findings underscore the importance of karst springs in modifying the abiotic conditions of fish habitat in mountain streams.

Radical Scavenging Capacity and In Vitro Cytoprotective Effects of Great Salt Lake-Derived Processed Mineral Water.

The Great Salt Lake, located in Utah, USA, is a saltwater lake with no outlet and is surrounded by vast mountains and salt deserts. We aimed to use Great Salt Lake-derived processed mineral water (hereafter termed as GSL-MW) for maintaining oral health. Therefore, we examined its radical scavenging activity as an antioxidant and its cytoprotective effect on human gingival fibroblasts (hGFs). The scavenging activity against O2•- radicals was determined by an electron spin resonance (ESR)-spin trapping technique using two kinds of O2•- generation systems; however, we could not reach any concrete conclusion because of the interference caused by GSL-MW in both systems. Detection of ·OH radicals using the ESR-spin trapping technique and kinetic analyses using double-reciprocal plots (corresponding to Lineweaver-Burk plots that are used to represent enzyme kinetics) revealed that GSL-MW has the ability to scavenge ·OH radicals. GSL-MW also showed a weak 2,2-diphenyl-1-picrylhydrazyl (DPPH; a stable radical)-scavenging activity. Regarding the cytoprotective effects, subconfluent hGFs pretreated with 10× and 100× dilutions of GSL-MW for 3 min and then exposed to harsh environmental conditions, such as pure water or 100 μM H2O2 for 3 min, showed enhanced cell viability rate. Moreover, 10× and 100× dilutions of GSL-MW reduced oxidative damage in confluent hGFs exposed to 12.5 and 25 mM H2O2. Our findings show that GSL-MW has antioxidant potential and cytoprotective effects on hGFs, suggesting that GSL-MW can be used to maintain oral health.

Elimination of malachite green by modified Fenton like process. Application of Box Behnken design

<p style="line-height:200%;text-align:justify;"><span style="line-height:200%;" lang="EN-US">The aim of this work was to investigate an advanced oxidation process for removing malachite green from aqueous solutions using a modified Fenton-like process. An experimental Box-Behnken design was applied to determine the optimal conditions by examining the effects of catalyst concentration ([Fe<sup>2+</sup>]), oxidant concentration ([K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>]), and stirring speed. The analysis of variance (ANOVA) indicated that oxidant concentration was the most significant factor, with a p-value of 0.001, while catalyst concentration, the quadratic term of the oxidant, and the interaction between catalyst concentration and stirring speed were also significant. The optimal conditions for maximum dye removal were found to be a catalyst concentration of 3.5 ppm, an oxidant concentration of 3.07 ppm, and a stirring speed of 200 rpm, achieving a theoretical degradation yield of 100% and an experimental yield of 98%. This agreement validates the model and the importance of the optimized parameters. Additionally, degradation kinetics studies in various natural waters revealed that oxidation efficiency followed this order: Distilled water (98%) > Seawater ≈ Industrial water (88.97%) > Source water (85.57%) > Mineral water (80.52%).</span></p>

Study of cellulose nanocrystals -enhanced natural gas foam performance and profile control & oil displacement mechanism

ABSTRACT To address the poor performance of conventional natural gas foam flooding in the tight conglomerate reservoirs of the Mahu region in Xinjiang, a high-activity green material, cellulose nanocrystals (CNC), was introduced to improve foam performance based on a conventional AOS+SDS foam system. However, the impact of CNC on the performance of the conventional foam system and the synergistic effects between CNC and surfactants are not yet clear. Therefore, this study evaluates the improvement effects of CNC on foam performance from both macroscopic and microscopic perspectives by analyzing the foam composite index and the synergistic effects between CNC and surfactants. The study also investigates the factors affecting foam performance and uses a planar visualization model to evaluate the enhanced gas foam flooding effects from a microscopic mechanism perspective. The results indicate that CNC increases the foam composite index by 26,850 mL·min on a macroscopic level. Microscopically, it makes the foam more compact, thickens the foam liquid film by 0.1 mm, improves the wettability reversal by 10%, and reduces the oil-water interfacial tension by 0.26 mN/m. After mixing 1 vol% crude oil, the foam volume and half-life decrease by 12% and 4%, respectively. At reservoir temperature and pressure, the foam volume decreases by 12.7% and 10.5%, but the half-life increases by 4 hours and 3.7 hours, respectively. At formation water mineralization conditions, the foam volume and half-life decrease by 6.6% and 1.7 hours, respectively. In summary, it still has good performance under reservoir conditions. The visualization model demonstrates from a microscopic perspective that the foam system has good gas shutoff capability. After foam flooding, the gas sweep efficiency increases by 54.12%, and the foam flooding and subsequent gas flooding improve the crude oil recovery by 20.32%.

Importance of Clay Swelling on the Efficacy of Cyclic Steam Stimulation in the East Moldabek Formation in Kazakhstan

Both steam and hot water flooding of high-viscosity oils in the presence of swelling clays are difficult methods for producing oil efficiently because of potential formation permeability reduction. This paper pertains to heavy oil recovery from the East Moldabek formation where the oil API gravity is about 22 and is inundated with swelling clays. To achieve this, we used the IntersectTM reservoir simulator to compare oil recovery economics using both hot water and steam injection as a function of steam cycle duration, temperature, and steam dryness. We also studied clay swelling in the East Moldabek formation where clay poses a significant challenge due to its impact on permeability reduction. In this research, we developed an equation based on experimental data to establish a relationship between water mineralization and permeability in the East Moldabek formation. The equation provides valuable insight on how to mitigate clay swelling which is crucial for enhancing oil recovery efficiency—especially in sandstone reservoirs. Our modeling studies provide the recovery efficiencies for salinities of the hot water EOR versus cyclic steam EOR methods in a formation containing swelling clays. Specifically, the reduction in formation permeability as a function of the distilled water fraction is the controlling parameter in hot water or steam flooding—when the formation water mixture becomes less saline, oil recovery decreases. Our research shows that clay swelling can significantly impact cyclic steam stimulation outcomes, potentially reducing its effectiveness, while hot water flooding may offer a more cost-effective and operationally feasible solution in formations where clay swelling is a concern. Economic analysis reveals the potential for achieving an optimal favorable condition for hot water injection. Therefore, this paper provides a guideline on how to conduct thermal oil recovery for heavy oils in fields with high clay content such as the East Moldabek deposit.

Flora and vegetation in the Lake Arbakalir and the spring Charsky Goryachy Klyuch (Charskaya Basin, Transbaikalia)

As a result of comprehensive researches in the Lake Arbakalir and the Spring Charsky Goryachi klyuch during the growing season in 2021, the physical and chemical parameters of water, species and phytocenotic diversity of vegetation were studied. 56 taxa from 7 divisions of which 31 species belong to flowering plants, 22 species to macroalgae, one species in each to bryophytes, horsetails and lycophytes were identified in the flora of water bodies. Two species are included in the Red Book, both at the federal and regional levels. Two species are classified as relict. The structure of the flora contains species of three ecotypes, of which 38 species (67.9 %) belong to true aquatic plants. 18 associations from 12 formations were identified in the syntaxonomic structure of aquatic and coastal aquatic vegetation. Based on factor analysis, the main factors influencing the distribution of phytocenoses are water temperature, pH, mineralization, and main cation, anion and nutrient contents.

Isolation of Bacillus altitudinis 5-DSW with Protease Activity from Deep-Sea Mineral Water and Preparation of Functional Active Peptide Fractions from Chia Seeds.

In this study, we successfully isolated Bacillus strains with high protease activity from deep-sea mineral water in Korea and used them to obtain functional peptide fractions from chia seeds. The obtained Bacillus strains showed a high similarity of 99% with B. altitude with a long rod type (named B. altitudinis 5-DSW) and high protease activity at 40 °C, and 70% of the activity remained even at 70 °C. The defatted chia seed protein (15-50 kDa) was treated with crude protease from B. altitudinis 5-DSW and digested into small peptides below 20 kDa. The obtained chia seed peptides showed 3 times and 1.5 times higher antioxidant activity in DPPH and ABT radical scavenging assays, respectively. Moreover, chia seed peptides showed enhanced AChE inhibitory activity with an IC50 value of 14.48 ± 0.88 μg/mL and BChE inhibition activity with an IC50 value of 10.90 ± 0.80 μg/mL. Our results indicate that the newly isolated B. altitudinis 5-DSW and chia seed protein hydrolysates have potential applications in biotechnology and functional food development, enhancing the nutritional quality and value-added utilization of chia byproducts.

Harnessing the Power of Natural Mineral Waters in Bread Formulations: Effects on Chemical, Physical, and Physicochemical Properties

Harnessing the Power of Natural Mineral Waters in Bread Formulations: Effects on Chemical, Physical, and Physicochemical Properties

Anti-Inflammatory Effect of Deep-Sea Mineral Water on LPS-Induced Inflammation in Raw 264.7 Murine Macrophage Cells and Zebrafish Larvae

Deep-sea mineral water (DSW) consists of different compositions and properties. The composition can be varied in different seas all around the world. However, previous studies have investigated that DSW is a potential candidate that can be used to prevent different inflammatory diseases. Even though inflammation is an important protective mechanism in an animal, excessive inflammation causes organ failure and ultimate death. Therefore, the present study was carried out to investigate the anti-inflammatory effect of DSW extracted from the South Korean Sea to unveil its potential as an anti-inflammatory drug. To perform this, first, we have compared the cytotoxic effect of DSW on RAW 264.7 murine macrophage cells with NaCl and normal-sea water (NSW). Results reveal that DSW enhances cell survival while other treatments negatively affect cell survival. Furthermore, we have investigated that DSW reduces the LPS-induced cell apoptosis compared to the NaCl- and NSW-treated cells. Moreover, DSW has the ability to suppress the pro-inflammatory cytokine transcription (TNF-α, IL-1β, and IL-6) and NO production upon LPS treatment. In-vivo survival assay in zebrafish larvae shows a more than 50% survival rate in 10, 20, 30, 40, or 50% concentrations of DSW-treated larvae compared to NaCl- or NSW-treated larvae. Further investigations unveiled that DSW can negatively regulate the neutrophil and macrophage recruitment to the inflammatory site, which was induced by fin-fold amputation in zebrafish larvae and pro-inflammatory cytokine (tnf-α, il-1β, and il-6) secretion. Taken together, the present study concluded that DSW may have the ability to act as an anti-inflammatory drug to suppress excessive inflammation and subsequent consequences.

A first-principles study of the effects of temperature on the atomic and electronic structures of Mg-montmorillonite with H2O molecule adsorption

The interaction between water and soft rock rich in clay minerals is one of the main factors causing damage in soft rock tunnel engineering. The effects of temperature on the atomic structure and water absorption capacities of clay minerals cannot be ignored. In the present study, the influence of temperature on the microstructure of Mg-montmorillonite and the thermal stability of the Mg-montmorillonite (010) surface were calculated based on density functional theory. Furthermore, the adsorption properties of H2O molecules within different coverages (0 < Θ ≤ 1.0 ML) on the (010) surface were investigated in the temperature range of 0–900 K. First, the volume of Mg-montmorillonite expanded significantly with increasing temperature along the z-axis direction. The surface energy of the Mg-montmorillonite (010) surface decreased with increasing temperature, indicating that the high temperature weakened the interatomic interactions on the surface. Moreover, the calculations demonstrated that H2O molecules could still be stably adsorbed on the Mg-montmorillonite (010) surface at different temperatures, and the order of stable adsorption configurations for a single H2O molecule was hollow > bridge > interlayer bridge > top sites. With increasing coverage of H2O molecules, the adsorption energies increased for the top sites, while decreased for the bridge, hollow, and interlayer bridge sites at high temperature. In addition, the changes in atomic structure and electronic characteristics during water absorption were further explored by calculating the ICOHP, PDOS, and lattice relaxation.

Passivation of metal sulfides by a marine bacterium for acid mine drainage control

Acid mine drainage originates from metal sulfides oxidation, which results in acidic metal-rich leachate. In this study, a novel and environmentally friendly approach was demonstrated to passivate pyrite and lead-zinc tailings, respectively. The key to this approach is to develop biofilms of the marine bacterium Qipengyuania flava S1. Biofilms can induce biomineralization, thereby isolating metal sulfides from air and water. The stability and biological toxicity of the bio-passivation layers were evaluated by leaching bio-passivated pyrite or tailings in initially acidic H2O2 solutions with shaking for 180 days and then cultivating Brassica chinensis and Allium cepa with the leachates. Our results showed that after passivation, the amount of iron released by pyrite decreased by at least 99.2 ± 0.2 (in wt%). For lead-zinc tailings after passivation, the released metal ions (Fe+Al+Pb+Zn) decreased by at least 52.0 ± 3.2 (in wt%). The bio-passivation layers also maintained the pH of the leachate in the range of 7.5–8.0. Before bio-passivation, compared with mineral water, the pyrite leachate significantly inhibited the growth of the two plants, and the tailings leachate significantly inhibited the growth of A. cepa, whereas the bio-passivated pyrite or tailings leachate did not show any inhibitory effect.

Aquatic environment drives the emergence of cell wall-deficient dormant forms in Listeria

Stressed bacteria can enter a dormant viable but non-culturable (VBNC) state. VBNC pathogens pose an increased health risk as they are undetectable by growth-based techniques and can wake up back into a virulent state. Although widespread in bacteria, the mechanisms governing this phenotypic switch remain elusive. Here, we investigate the VBNC state transition in the human pathogen Listeria monocytogenes. We show that bacteria starved in mineral water become VBNC by converting into osmotically stable cell wall-deficient coccoid forms, a phenomenon that occurs in other Listeria species. We reveal the bacterial stress response regulator SigB and the autolysin NamA as major actors of VBNC state transition. We lastly show that VBNC Listeria revert to a walled and virulent state after passage in chicken embryos. Our study provides more detail on the VBNC state transition mechanisms, revealing wall-free bacteria naturally arising in aquatic environments as a potential survival strategy in hypoosmotic and oligotrophic conditions.