Oxalate Formation Research Articles

Evaluation Of Antiurolithiatic Activity Of Methanolic Seed Extracts Of Persea Americana Against Calcium Oxalate Induced Urolithiasis In Rats

Objective: Persea Americana methanolic seed extracts are considered for the present study to access its efficacy, urolithiasis is inducedby administering the male rats with calcium oxalate.Methods: Calcium oxalate urolithiasis is induced in male rats by means of hyperoxaluria model by administering ethylene glycol of0.75% v/v, with 1% w/v ammonium chloride supplemented in drinking water for 3 days followed by 0.75% v/v of ethylene glycol for25 days. The PAMSE is administered to urolithiasis induced test group at dose of 150mg/kg respectively for 28 days.Results: As anticipated after 28 days the calcium oxalate is deposited significantly in the kidney which is associated with the increaseof Urinary oxalate, Urine calcium & magnesium levels, serum uric acid, creatinine in urolithiasis control groups. ACP, ALP, AST &ALT well known biochemical parameters are seen to be increased with decreased level of LDH assessed using kidney homogenate,copiously confirming the induction of urolithiasis , its promising to know that the PAMSE intubation to the test group daily decreasedthe quantity of formation of calcium oxalate and all the biochemical changes induced by urolithiasis is reverted.Conclusion: Results from this study shows that PAMSE is effective inhibitor of crystallization of calcium oxalate comparable to thestandard Cystone in dose dependent mode. Therefore indicating PAMSE’s significant antiurolithiatic activity.

PSXI-2 Circulating Mirnas as non-Invasive Biomarkers of Chronic Kidney Disease and Calcium Oxalate Uroliths in Felines

Abstract Chronic kidney disease (CKD), characterized by progressive loss of kidney function, is a major cause of mortality in cats. Another complication is the formation of calcium oxalate (CaOx) uroliths in the bladder and kidneys of cats, where inflammation has a role in its pathogenesis. MicroRNAs (miRNAs) are small non-coding RNAs which bind to the target mRNA to reduce its function. Depending on the target mRNA, they regulate transcription of several pro-inflammatory genes. We assessed the expression profiles of circulating miRNAs in blood, collected at the natural end-of-life in colony cats, in a retrospective study, in healthy (n=10; 5.9-16 yr), CaOx (n=10, 8.6-13.4 yr), and CKD (n=10; 8.3-15.4 yr). Circulating concentrations of creatinine, symmetric dimethylarginine, and blood urea nitrogen were significantly greater in CaOx and CKD cats compared with controls, indicating kidney dysfunction. Expression of miRNAs, measured by qRT-PCR, was analyzed using the ΔΔCt method and normalized to U6. There was a significant upregulation of miR-155 in CaOx stone formers compared with controls (p< 0.05). miR-155 is increased in the serum and urine of human patients with nephrolithiasis. miR-155 can also promote oxalate-induced renal oxidative stress by suppressing MGP expression. In humans, miR-155 concentrations are negatively correlated with cytokines including IL-1β, IL-6, and TNF-α, suggesting the involvement of inflammation in nephrolithiasis. However, miR-155 was downregulated in CKD compared with controls. miR-16 was also downregulated in CKD cats. Consistent with this, there is downregulation of both the miRNAs in human patients with Stage 4 CKD. Further, miRNAs downregulated in CaOx, but not in CKD, included miR-17, miR-19b, miR-27a, and miR-27b, whereas let-7a, miR-15a, miR-16, miR-29b, and miR-200a were downregulated only in CKD cats. Taken together, the profile of circulating miRNAs in CaOx and CKD cats may serve as important biomarkers in the initiation and progression of renal dysfunction in cats.

Insight into Source and Evolution of Oxalic Acid: Characterization of Particulate Organic Diacids in a Mega-City, Shanghai from 2008 to 2020

Organic acids are important aerosol compositions with significant implications on particle formation, growth, acidity, phase state, and environmental impacts. Oxalic acid was found to be the most abundant particulate organic diacid in Shanghai during the study period, accounting for ~58% of the total dicarboxylic acids (C2–C10). Biomass burning (BB) explained a small but non-negligible fraction (less than 10%) of oxalate. Significant correlations between oxalate and sulfate indicated a potentially synergistic formation mechanism of oxalate and sulfate. In addition, meteorological factors such as ambient temperature and relative humidity were found to influence the formation of oxalate. Higher oxalate relative to inorganic particulate content was found in summer. Potential source contribution function analysis suggested that most of the oxalate observed in Shanghai was produced locally. The formation of oxalate was largely impacted by atmospheric oxidation capacity as indicated by its significant correlations with both secondary organic carbon (SOC) and sulfur oxidation ratio (SOR). The evolution of oxalate, oxalate/sulfate, oxalate/organic carbon were consistent with the emission trend of volatile organic carbons (VOCs) in recent years, indicating that oxalate may be derived from secondary oxidation of VOCs, which is further confirmed by a positive relationship between Ox and oxalate/VOCs over the study period. With a detailed characterization of oxalate in Shanghai, our study highlights the importance of regulating primary emissions, such as VOCs, as well as mitigation of atmospheric oxidation capacity in controlling air pollution in a coastal megacity.

Nephro-protective effect of Daphnetin in hyperoxaluria-induced rat renal injury via alterations of the gut microbiota.

It is well proved that hyperoxaluria induces the renal injury and finally causes the end stage kidney disease. Daphnetin (coumarin derivative) already confirmed renal protective effect in renal model, but hyperoxaluria protective effect still unexplore. The objective of this research was to scrutinize the renal protective effect of daphnetin against ethylene glycol (GC)-induced hyperoxaluria via altering the gut microbiota. GC (1% v/v) was used for the induction of hyperoxaluria in the rats and the rats were received the oral administration of daphnetin (5, 10 and 15 mg/kg). The body and renal weight were assessed. Urine, renal, inflammatory cytokines, antioxidant, inflammatory parameters, and gut microbiota were appraised. Daphnetin effectually improved the body weight and reduced the renal weight. Its also remarkably boosted the magnesium, calcium, citrate level and suppressed the level of uric acid and oxalate formation. Daphnetin significantly (p < .001) ameliorate the level of urinary kidney injury molecule 1 (KIM-1), blood urea nitrogen (BUN), urea, serum creatinine (Scr), neutrophil gelatinase-associated lipocalin (NGAL) and uric acid along with inflammatory cytokines and inflammatory mediators. Daphnetin considerably repressed the malonaldehyde (MDA) level, protein carbonyl and improved the level of glutathione reductase (GR), superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT). Daphnetin treatment considerably altered the microbial composition of different bacteria at phylum, genus and family level. Daphnetin significantly suppressed the Firmicutes relative abundance and boosted the Bacteroidetes relative abundance. Our result clearly indicated that daphnetin remarkably ameliorates the GC induced hyperoxaluria in rats via altering the oxidative stress, inflammatory reaction and gut microbiota. PRACTICAL APPLICATION: Nephrotoxicity is a serious health disease worldwide. We induce the renal toxicity in the experimental rats using the ethylene glycol and scrutinized the renal protective effect of daphnetin. Daphnetin considerably suppress the renal, urine parameters. For estimation the underlying mechanism, we estimated the gut microbiota in all group rats. Daphnetin remarkably altered the level of gut microbiota and suggesting the renal protective effect.

Fulvic Acid from Chestnut Forest as an Added Qualities to Spring Water: Isolation and Characterization from Fiuggi Waters

The aquifer of “mineral” water, historically known for its curative properties, is an identifying characteristic of the Anticolana valley. This area hosted a coppice chestnut forest for a long time. Under the forest, there is an important aquifer, historically renowned and widely recognized for preventing renal stone formation and or facilitating their expulsion. This mineral water pre- vents the formation of calcium oxalate and phosphate crystals in the kidney and promotes their dissolutions through soluble calcium complexes. The forest environment soil is particularly rich in humification products owing to the interaction of the rainwater–litter–soil system. The fulvic fraction is soluble in water under all pH conditions and enriches the water basin. We aimed to test these hypotheses and assess how the coppice chestnut forest is involved in fulvic acid production. Fulvic fractions isolated and purified from soil samples and mineral water (550 μg L−1) were analyzed by GC-MS, FTIR, and NMR. Data from different sources were compared, showing sufficient similarities to state that the fulvic acids isolated from the water come from the processes that take place between the stems and the chestnut litter. The chestnut forest provides enrichment to water quality, which is a distinctive piece of information in defining water enhancement strategies, establishing soil management and designating sustainable forest management.

Electrocrystallization of Calcium Oxalate on Electrospun PCL Fibers Loaded with Phytic Acid as a Template.

Crystallization occurs widely in living organisms where different organs could associate with the calcification process, such as the formation of calcium oxalate (CaOx) calculi in the urinary tract. However, the pathogenesis and the role of an inhibitor in the pathological processes involved in urolithiasis is poorly understood. Therefore, the use of phytic acid (PA) as an inhibitor for the organic fibrillar matrix is a novel approach to inhibit the formation of pathological CaOx crystals. Herein, electrospun polymer fiber meshes of polycaprolactone (PCL) with random (R) and aligned (A) fiber orientations containing PA were prepared by electrospinning, and their role as a 3D organic template in in vitro CaOx crystallization was investigated. CaOx crystals were generated on conductive tin indium oxide (ITO)-modified glass with R-PCL and A-PCL fibers in the presence of PA through an electrocrystallization (EC) procedure. This study provides a simple electrochemical approach to evaluate the role of PA as an inhibitor in the nucleation of pathological CaOx crystals. The resulting CaOx crystals were analyzed by chrono-potentiometry, optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). We found that PA and the fiber orientations are key factors in the nucleation and crystal growth of CaOx, achieving the stabilization of healthy CaOx crystal and the inhibition of the pathological crystal form.

Vinegar reduced renal calcium oxalate stones by regulating acetate metabolism in gut microbiota and crystal adhesion in rats.

Urolithiasis is a common urologic disease. Higher consumption of vinegar was associated with a lower risk of urolithiasis. Recent studies reported that disorder of gut microbiota and injury of the tight junction of renal tubular epithelial cells were associated with the formation of renal calcium oxalate (CaOx) stones. We aimed to explore the mechanism of vinegar reduced renal CaOx stone formation by regulating gut microbiota and the tight junction of renal tubular epithelial cells. Thirty Sprague-Dawley rats were randomly allocated to control group, model group and vinegar group. Rats in control group got 2ml/kg of sterile water by gavage. Model group rats were additionally supplied with drinking water with 1% (v/v) ethylene glycol (EG) every day. Rats in vinegar group had 1% (v/v) EG in drinking water and were gavaged with 2ml/kg of vinegar (5% acetate) every day. Vinegar reduced renal CaOx crystals and urinary oxalate. Vinegar increased the relative abundances of Ruminococcus gauvreauii, Ruminococcus torques, Ruminococcus-2, Moryella, Enterococcus, Alistipes, and Parabacteroides in the gut microbiota. Blood acetate increased in vinegar group. The renal tight junction occludin protein decreased in the model group and increased in the vinegar group. Studies in vitro verified that acetate could reverse the decline in occludin expression induced by CaOx crystals and inhibit CaOx crystal adhesion to cells. Vinegar reduced renal CaOx stones by regulating gut microbiota and increasing blood acetate to restore renal tight junction and reduce CaOx crystal adhesion.

Identification of Human Alanine-Glyoxylate Aminotransferase Ligands as Pharmacological Chaperones for Variants Associated with Primary Hyperoxaluria Type 1.

Primary hyperoxaluria type I (PH1) is a rare kidney disease due to the deficit of alanine:glyoxylate aminotransferase (AGT), a pyridoxal-5′-phosphate-dependent enzyme responsible for liver glyoxylate detoxification, which in turn prevents oxalate formation and precipitation as kidney stones. Many PH1-associated missense mutations cause AGT misfolding. Therefore, the use of pharmacological chaperones (PCs), small molecules that promote correct folding, represents a useful therapeutic option. To identify ligands acting as PCs for AGT, we first performed a small screening of commercially available compounds. We tested each molecule by a dual approach aimed at defining the inhibition potency on purified proteins and the chaperone activity in cells expressing a misfolded variant associated with PH1. We then performed a chemical optimization campaign and tested the resulting synthetic molecules using the same approach. Overall, the results allowed us to identify a promising hit compound for AGT and draw conclusions about the requirements for optimal PC activity.

Formation and growth of cerium (III) oxalate nanocrystals by liquid-cell transmission electron microscopy

Using rare earth elements as analogs for actinide series elements enables studying the chemistry of these radioactive materials without the inherent risks. A fundamental understanding of the nucleation and growth of actinide oxalates is crucial for processing nuclear waste. Using in-situ liquid cell TEM (LC-TEM), we show particle attachment processes occurring during the nucleation and growth of cerium oxalate. The early stages of the observed non-classical growth mechanisms have important implications for particle evolution and predictions of final particle morphology. We observed particle formation via monomer-by-monomer addition or the particle aggregation pathway depending on the selected precursor concentration. At the highest precursor concentration at a high dose rate, we observed particle alignment in a branch structure is due to the interfacial instability. It was demonstrated that in-situ LC-TEM is an invaluable tool in studying the cerium oxalate formation and ultimately a path to understanding actinide chemistry.

Production of AB5 materials from spent Ni-MH batteries with further tests of hydrogen storage suitability

A novel approach for the reuse of rare earth (REE) elements generated during hydrometallurgical processing of Ni-MH batteries as alternative sources is provided to valorize Ni-MH batteries wastes. The production of AB5-based alloys from spent Ni-MH waste was thoroughly investigated. The REE elements were recovered as a mixture in oxalate form and annealed at 900 °C to obtain a single-phase REEs oxide REE2O3. Citrate gel and glycine nitrate processes followed by the Ca reduction process under H2 atmosphere were used to produce the AB5 alloys. The alloys were successfully produced, and their crystal structure and morphology have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with supporting energy-dispersive X-ray (EDS) analysis. Nanoparticles with a size of 173±3 nm and 150±8 nm were observed using transmission electron microscopy (TEM) for CG and GNP alloys. Studied samples were subjected to hydrogenation, and the structural changes were depicted.

OXALATE-CALCIUM RATIOS OF COMMON CEREALS CONSUMED IN EASTERN NIGERIA

The importance of Oxalate content of an individual plant in limiting total dietary calcium availability is of significance when the ratio oxalic to calcium (oxa:cal.) is greater than one. Food with oxal: cal ratio greater than two, have no utilizable calcium and contain excess oxalate while foodstuff with oxal:cal. of about one provides little calcium but do not inhibit the utilization of calcium provided by other products. The study analysed three commonly consumed cereals of oxalic acids and calcium by rigorous classical quantitative method of precipitation/titration and atomic absorption spectrophotometry, respectively. The result should oxal:cal. ratios&gt;1 for all the cereals indicating that the cereals have no utilizable calcium, thus contain excess oxalate which not only complex the calcium contained in the food but also that derived from other food sources eaten together with it. This can result in deficiency of such an essential mineral as calcium in the body and even render the body prone to bone diseases and possibility of developing kidney stones due to calcium oxalate formation (calcium oxalate being the most common component of kidney stone).

Using Light and Electrons to Bend Carbon Dioxide: Developing and Understanding Catalysts for CO2 Conversion to Fuels and Feedstocks.

Our global society generates an unwieldy amount of CO2 per unit time. Therefore, the capture of this greenhouse gas must involve a diverse set of strategies. One solution to this problem is the conversion of CO2 into a more useful chemical species. Again, a multiplicity of syntheses and products will be necessary. No matter how elegant the chemistry is, commercial markets often have little use for a small set of compounds made in tremendous yield. Following this reasoning, the Bocarsly Research Group seeks to develop new electrochemical and photochemical processes that may be of utility in the conversion of CO2 to organic compounds. We focus on investigating proton-coupled charge transfer mechanisms that produce both C1 and carbon-carbon bonded products (C2+).In early work, we considered the reduction of CO2 to formate at electrocatalytic indium and tin electrodes. These studies demonstrated the key role of surface oxides in catalyzing the reduction of CO2. This work generated efficient systems for the formation of formate and paved the way to studies using non-copper, intermetallic electrocatalysts for the generation of C2+ species. Most notable is the efficient formation of oxalate at an oxidized Cr3Ga electrode. Oxalate has recently been suggested as a potential nonfossil, alternate organic feedstock.Separately, we have focused on the electrocatalytic effects of pyridine on the reduction of CO2 in aqueous electrolyte. These studies demonstrated that electrodes that normally yield a low hydrogen overpotential (Pd and Pt) show suppressed H2 evolution and strongly enhanced activity for CO2 reduction in the presence of pyridinium. Methanol was observed to form in high Faradaic yield at low overpotential using this system. The 6-electron, 6-proton reduction of CO2 in the presence of pyridinium was intriguing, and significant effort was placed on understanding the mechanism of this reaction both on metal electrodes and on semiconducting photocathodes. P-GaP electrodes were found to provide exceptional behavior for the formation of methanol using only light as the energy source.The pyridinium studies highlighted the role of protons in the overall reduction of CO2, stimulating our interest in the chemistry of MnBr(bpy)(CO)3 and related compounds. This complex was reported to electrochemically reduce CO2 to CO. We saw these reports as an opportunity to study the detailed nature of the proton-coupled electron transfer (PCET) mechanism associated with CO2 reduction. Our investigation of this system revealed the role of hydrogen-bonding in CO2 reduction and pointed the way for the construction of a photochemical process for CO generation using a [(bpy)(CO)3Mn(CN)Mn(bpy)(CO)3]+ photocatalyst.Based on our studies to date, it appears likely that heterogeneous systems can be assembled to convert CO2 into products that are "beyond C2 products." This may open up new practical chemistry in the area of fossil-based replacements for both synthesis and fuels. Systems with pragmatic efficiencies are close to reality. Electrochemical reactors using heterogeneous electrocatalysts show the stability and product selectivity needed to generate industrial opportunities. Continued growth of mechanistic understanding is expected to facilitate the chemical design of cogent systems for the taming of CO2.

Formation of carbonate and oxalate species on a Cobalt-modified Fe3O4(111) surface: Comparison of DFT+U, hybrid functionals, and the random phase approximation

We discuss the formation of carbonate, CO32-, and the thermodynamically competing formation of a planar oxalate, C2O42-, species in a Co-modified (111) surface of magnetite. The structure corresponds to a Cooct2-Fetet1-terminated (111)-(1 × 1) surface of Fe3O4. It appears that the conversion of CO2 into oxalate involves host-guest-type of interactions due to the cup-like morphology of the surface. As our system of interest is known to be challenging for electronic structure methods in terms of accuracy, we compare GGA-PBE(+U) results with results obtained using the computationally more costly and supposedly more accurate HSE hybrid functional, as well as the random phase approximation (RPA). While PBE+U and HSE predict thermodynamically competing species, RPA predicts C2O42- to be substantially more stable than two individual carbonate species on the surface. We discuss infra-red vibrational bands and suggest scanning tunneling microscopy to directly prove the formation of this surface oxalate species, because of characteristic and readily recognizable butterfly-like images.

Revisiting Reduction of CO2 to Oxalate with First-Row Transition Metals: Irreproducibility, Ambiguous Analysis, and Conflicting Reactivity.

Construction of higher C≥2 compounds from CO2 constitutes an attractive transformation inspired by nature’s strategy to build carbohydrates. However, controlled C–C bond formation from carbon dioxide using environmentally benign reductants remains a major challenge. In this respect, reductive dimerization of CO2 to oxalate represents an important model reaction enabling investigations on the mechanism of this simplest CO2 coupling reaction. Herein, we present common pitfalls encountered in CO2 reduction, especially its reductive coupling, based on established protocols for the conversion of CO2 into oxalate. Moreover, we provide an example to systematically assess these reactions. Based on our work, we highlight the importance of utilizing suitable orthogonal analytical methods and raise awareness of oxidative reactions that can likewise result in the formation of oxalate without incorporation of CO2. These results allow for the determination of key parameters, which can be used for tailoring of prospective catalytic systems and will promote the advancement of the entire field.

Atmospheric Chemistry of Oxalate: Insight Into the Role of Relative Humidity and Aerosol Acidity From High‐Resolution Observation

AbstractOxalate is the product of the precursors that can eventually be oxidized into oxalate by atmospheric oxidants (O3, etc.) and then redistributed to the particle phase, which has an impact on acid rain, and even the climate. However, we are still unclear about the influence of typical atmospheric oxidants in different phases with different RH and pH on oxalates. Here, we analyzed the effects of typical oxidants at RH ≤ 30%, 30% &lt; RH ≤ 80% of the atmosphere on oxalates in atmospheric particulates based on high‐resolution online observation in Nanjing: the chemical processes of O3, OX (=O3 + NO2), and Cl− in different RH all have an important influence on the oxalate level, especially at 30% &lt; RH ≤ 80% with high humidity have greater influence. NO2 only affects the particulate oxalate at RH ≤ 30%; HONO shows a greater effect at RH ≤ 30%, and 30% &lt; RH ≤ 80% in winter and summer, the atmospheric oxidants that dust participates in have little effect. At the same time, we also found the difference between the influence of pH on atmospheric oxalate in winter and summer at RH &gt; 80%, among which high pH is beneficial to the formation of oxalate in summer, while in winter has a greater influence on oxalate at RH ≤ 30%. These results help us to systematically understand the influence and distribution of oxalate in the atmosphere by RH, pH, and typical atmospheric oxidants.

Abiotic Formation of Calcium Oxalate under UV Irradiation and Implications for Biomarker Detection on Mars.

A major objective in the exploration of Mars is to test the hypothesis that the planet has ever hosted life. Biogenic compounds, especially biominerals, are believed to serve as biomarkers in Raman-assisted remote sensing missions. However, the prerequisite for the development of these minerals as biomarkers is the uniqueness of their biogenesis. Herein, tetragonal bipyramidal weddellite, a type of calcium oxalate, is successfully achieved by UV-photolyzing pyruvic acid (PA). The as-prepared products are identified and characterized by micro-Raman spectroscopy and field emission scanning electron microscopy. Persistent mineralization of weddellite is observed with altering key experimental parameters, including pH, Ca2+ and PA concentrations. In particular, the initial concentration of PA can significantly influence the morphology of weddellite crystal. Oxalate acid is commonly of biological origin; thus calcium oxalate is considered to be a biomarker. However, our results reveal that calcium oxalate can be harvested by a UV photolysis pathway. Moreover, prebiotic sources of organics (e.g., PA, glycine, alanine, and aspartic acid) have been proven to be available through abiotic pathways. Therefore, our results may provide a new abiotic pathway of calcium oxalate formation. Considering that calcium oxalate minerals have been taken as biosignatures for the origin and early evolution of life on Earth and astrobiological investigations, its formation and accumulation by the photolysis of abiological organic compounds should be taken into account.

Calcium oxalate crystallization in synthetic urinary medium: the impact of resorcinares and calixarenes

The impact of macrocycles on calcium oxalate formation. Calcium oxalate is a major component of kidney stones, an ailment that affects many people globally.

Association between hyperlipidemia and calcium oxalate lower urinary tract uroliths in dogs.

BackgroundMetabolic syndrome is associated with formation of calcium oxalate (CaOx) uroliths in humans.ObjectivesTo investigate the association between obesity and hyperlipidemia with CaOx lower urinary tract uroliths in client‐owned dogs.AnimalsDogs with (n = 55, U [uroliths]‐dogs) and without (n = 39, UF [uroliths‐free]‐dogs) CaOx lower urinary tract uroliths.MethodsCase‐control study. U‐dogs were retrospectively enrolled and compared to UF‐dogs. Body condition score (BCS; 1‐9 scoring scale), serum triglyceride (TG) and total cholesterol (CH) concentrations and glycemia (after >12‐hour food withholding) were recorded in both groups.ResultsOn univariate logistic regression, when excluding Miniature Schnauzers, odds of having uroliths increased by a factor of 3.32 (95% CI 1.38‐11.12) for each mmol/L of TG (P = .027), of 39 (95% CI 9.27‐293.22) for each mmol/L of glycemia (P < .0001), and of 2.43 (95% CI 1.45‐4.45) per unit of BCS (P = .002). In multivariable models, the effect of TG was retained when all breeds were included for analysis and odds of having uroliths increased by a factor of 4.34 per mmol/L of TG (95% CI 1.45‐19.99; P = .02).Conclusions and Clinical ImportanceSerum lipid screening in dogs diagnosed with CaOx uroliths might be recommended to improve their medical staging and management.

Copper oxalate formation by lichens and fungi

The present work focuses on the revealing the patterns of copper oxalates formation under the influence of lichens and fungi by combination of the results of field studies and model experiments. These findings create the scientific basis for the potential microbial technology applications (ore enrichment, monuments conservation, environment bioremediation, etc.). Copper oxalate moolooite Cu(C2O4)·H2O was discovered in saxicolous lichen Lecidea inops on the weathered chalcopyrite ore of Voronov Bor deposit (Central Karelia, Russia). Bioinspired syntheses of moolooite and wheatleyite Na2Cu(C2O4)2 2H2O with the participation of the microscopic fungi Aspergillus niger (active producer of oxalic acid) were carried out on weathered Cu-ore from the Voronov Bor deposit. It was shown that morphology of moolooite crystals is controlled both by the underlying rock and by the species composition of microorganisms. Iron ions (sourced from the underlying rock) in the crystallization medium inhibits the moolooite formation. The observed intensive dissolution of moolooite crystals are well explained by washing effect of the intratalline solutions which depends on repeatedly dehydration / rehydration cycles in the lichens. Joint interpretation of original and published data shows that moolooite along with other cooper oxalates are biominerals.

Microbial Volatile Organic Compound (VOC)-Driven Dissolution and Surface Modification of Phosphorus-Containing Soil Minerals for Plant Nutrition: An Indirect Route for VOC-Based Plant-Microbe Communications.

We investigated the ability of microbial volatile organic compounds (MVOCs) emitted by Bacillus megaterium (a well-known MVOC producer) to modify the dissolution kinetics and surface of hydroxyapatite, a natural soil mineral. Facilitated phosphate release was induced by the airborne MVOCs in a time-dependent manner. Use of each standard chemical of the MVOCs then revealed that acetic and oxalic acids are crucial for the phenomenon. In addition, the ability of such MVOCs to engineer the apatite surfaces was evidenced by FT-IR spectra showing the COO- band variation with incubation time and the prolonged acceleration of phosphate release during the negligible acidification of the hydroxyapatite-containing solutions. The formation of calcium oxalate was revealed through SEM-EDS and XRD analyses, suggesting that MVOC oxalic acid interacts with calcium ions, leading to the precipitation of calcium oxalate, thus preventing the recrystallization of calcium phosphates. Gel- and soil-based plant cultivation tests employing Arabidopsis thaliana and solid calcium phosphates (i.e., nano- and microsized hydroxyapatites and calcium phosphate dibasic) demonstrated that these MVOC mechanisms facilitate plant growth by ensuring the prolonged supply of plant-available phosphate. The relationship between the growth enhancement and the particle size of the calcium phosphates also substantiated the MVOC sorption onto soil minerals related to plant growth. Given that most previous studies have assumed that MVOCs are a molecular lexicon directly detected by the dedicated sensing machinery of plants, our approach provides a new mechanistic view of the presence of abiotic mediators in the interaction between plants and microbes via MVOCs.