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1.
Appl Microbiol Biotechnol ; 103(19): 7971-7982, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31486874

RESUMO

A nitrogen-starving isolation strategy was developed for the first time to screen bacteria with high calcium-precipitating activity (CPA) for bioremediation of damage in porous media. Meanwhile, a novel mini-tube method based on the detection of insoluble Ca2+ was established to evaluate the CPA of the isolates. A low-nitrogen-demanding strain B6, identified as Bacillus sp., was screened to exhibit the highest CPA (55 mM insoluble Ca2+). Furthermore, the effects of environmental factors and nutrient availability on B6-induced calcium precipitation were evaluated. The results show that nitrate and starch are the best nitrogen source and carbon source with optimal concentration being 4 and 2 g L-1, respectively. The suitable pH range for B6 to precipitate calcium is from 8.5 to 10.5. B6 can maintain the highest CPA at an initial spore concentration of 1.0 × 108 spores·mL-1. The optimal CaO2 dosage is 10 g L-1. Finally, the calcite precipitation is confirmed by ESEM, EDS, and XRD analysis.


Assuntos
Bacillus/metabolismo , Carbonato de Cálcio/metabolismo , Precipitação Química , Nitratos/metabolismo , Antiácidos , Bacillus/crescimento & desenvolvimento , Carbono/metabolismo , Meios de Cultura/química , Concentração de Íons de Hidrogênio , Nitrogênio/metabolismo , Amido/metabolismo
2.
Nat Commun ; 10(1): 3580, 2019 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395889

RESUMO

Ocean acidification is expected to negatively impact calcifying organisms, yet we lack understanding of their acclimation potential in the natural environment. Here we measured geochemical proxies (δ11B and B/Ca) in Porites astreoides corals that have been growing for their entire life under low aragonite saturation (Ωsw: 0.77-1.85). This allowed us to assess the ability of these corals to manipulate the chemical conditions at the site of calcification (Ωcf), and hence their potential to acclimate to changing Ωsw. We show that lifelong exposure to low Ωsw did not enable the corals to acclimate and reach similar Ωcf as corals grown under ambient conditions. The lower Ωcf at the site of calcification can explain a large proportion of the decreasing P. astreoides calcification rates at low Ωsw. The naturally elevated seawater dissolved inorganic carbon concentration at this study site shed light on how different carbonate chemistry parameters affect calcification conditions in corals.


Assuntos
Aclimatação , Antozoários/fisiologia , Calcificação Fisiológica , Carbonato de Cálcio/metabolismo , Fontes Hidrotermais/química , Animais , Antozoários/química , Carbonato de Cálcio/análise , Carbonato de Cálcio/química , Geografia , Concentração de Íons de Hidrogênio , Isótopos , México , Água do Mar/química
3.
Appl Microbiol Biotechnol ; 103(18): 7719-7727, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31363824

RESUMO

Rammed earth has been enjoying a renaissance as sustainable construction material with cement stabilized rammed earth (CSRE). At the same time, it is important to convert CSRE to be a stronger, durable, and environment-friendly building material. Bacterial application is established to improve cementitious materials; however, bioaugmentation is not widely acceptable by engineering communities. Hence, the present study is an attempt applying biostimulation approach to develop CSRE as sustainable construction material. Results showed that biostimulation improved the compressive strength of CSRE by 29.6% and resulted in 27.7% lower water absorption compared to control. The process leading to biocementation in improving CSRE was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope-energy dispersive spectrometer. Further, Illumina MiSeq sequencing was used to investigate changes in bacterial community structures after biostimulation that identified majority of ureolytic bacteria dominated by phylum Firmicutes and genus Sporosarcina playing role in biocementation. The results open a way applying biological principle that will be acceptable to a wide range of civil engineers.


Assuntos
Bactérias/metabolismo , Carbonato de Cálcio/metabolismo , Materiais de Construção/microbiologia , Consórcios Microbianos , Força Compressiva , Firmicutes/metabolismo , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Sporosarcina/metabolismo , Difração de Raios X
4.
Curr Microbiol ; 76(11): 1298-1305, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31428805

RESUMO

Geobacillus thermoglucosidasius NY05 catalyzes calcite single crystal formation at 60 °C by using acetate and calcium. Endospores are embedded at the central part of the calcite single crystal and carbon atoms in the calcite lattice are derived from acetate carbon. Here, we synthesized 21-mer antisense DNA oligonucleotides targeting sporulation transcription factor, acetate-CoA ligase, isocitrate lyase, and malate synthase G mRNAs and evaluated the effect of these oligonucleotides on calcite formation in G. thermoglucosidasius NY05. G. thermoglucosidasius NY05 cells containing antisense DNA oligonucleotides targeting sporulation transcription factor, acetate-CoA ligase, isocitrate lyase, and malate synthase G mRNAs had reduced calcite single crystal formation by 18.7, 50.6, 55.7, and 82.3%, respectively, compared with cells without antisense DNA oligonucleotides. These results support that calcite formation needs endospores as the nucleus to grow, and carbon dioxide generated from acetate, which is metabolized via the glyoxylate pathway and glucogenesis, is supplied to the crystal lattice.


Assuntos
Proteínas de Bactérias/genética , Carbonato de Cálcio/metabolismo , Inativação Gênica , Geobacillus/genética , Acetatos/metabolismo , Proteínas de Bactérias/metabolismo , Cálcio/metabolismo , Carbonato de Cálcio/química , Geobacillus/química , Geobacillus/metabolismo , Glioxilatos/metabolismo , Isocitrato Liase/genética , Isocitrato Liase/metabolismo , Malato Sintase/genética , Malato Sintase/metabolismo
5.
J Appl Microbiol ; 127(5): 1479-1489, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31301204

RESUMO

AIMS: Development of biomineralization technologies has largely focused on microbially induced carbonate precipitation (MICP) via Sporosarcina pasteurii ureolysis; however, as an obligate aerobe, the general utility of this organism is limited. Here, facultative and anaerobic haloalkaliphiles capable of ureolysis were enriched, identified and then compared to S. pasteurii regarding biomineralization activities. METHODS AND RESULTS: Anaerobic and facultative enrichments for haloalkaliphilic and ureolytic micro-organisms were established from sediment slurries collected at Soap Lake (WA). Optimal pH, temperature and salinity were determined for highly ureolytic enrichments, with dominant populations identified via a combination of high-throughput SSU rRNA gene sequencing, clone libraries and Sanger sequencing of isolates. The enrichment cultures consisted primarily of Sporosarcina- and Clostridium-like organisms. Ureolysis rates and direct cell counts in the enrichment cultures were comparable to the S. pasteurii (strain ATCC 11859) type strain. CONCLUSIONS: Ureolysis rates from both facultatively and anaerobically enriched haloalkaliphiles were either not statistically significantly different to, or statistically significantly higher than, the S. pasteurii (strain ATCC 11859) rates. Work here concludes that extreme environments can harbour highly ureolytic active bacteria with potential advantages for large scale applications, such as environments devoid of oxygen. SIGNIFICANCE AND IMPACT OF THE STUDY: The bacterial consortia and isolates obtained add to the possible suite of organisms available for MICP implementation, therefore potentially improving the economics and efficiency of commercial biomineralization.


Assuntos
Álcalis/metabolismo , Carbonato de Cálcio/metabolismo , Sporosarcina/metabolismo , Ureia/metabolismo , Anaerobiose , Bactérias/metabolismo , Carbonato de Cálcio/química , Sedimentos Geológicos/microbiologia , Consórcios Microbianos , Sporosarcina/genética , Sporosarcina/isolamento & purificação
6.
Geobiology ; 17(6): 676-690, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31347755

RESUMO

Several species of cyanobacteria biomineralizing intracellular amorphous calcium carbonates (ACC) were recently discovered. However, the mechanisms involved in this biomineralization process and the determinants discriminating species forming intracellular ACC from those not forming intracellular ACC remain unknown. Recently, it was hypothesized that the intensity of Ca uptake (i.e., how much Ca was scavenged from the extracellular solution) might be a major parameter controlling the capability of a cyanobacterium to form intracellular ACC. Here, we tested this hypothesis by systematically measuring the Ca uptake by a set of 52 cyanobacterial strains cultured in the same growth medium. The results evidenced a dichotomy among cyanobacteria regarding Ca sequestration capabilities, with all strains forming intracellular ACC incorporating significantly more calcium than strains not forming ACC. Moreover, Ca provided at a concentration of 50 µM in BG-11 was shown to be limiting for the growth of some of the strains forming intracellular ACC, suggesting an overlooked quantitative role of Ca for these strains. All cyanobacteria forming intracellular ACC contained at least one gene coding for a mechanosensitive channel, which might be involved in Ca influx, as well as at least one gene coding for a Ca2+ /H+ exchanger and membrane proteins of the UPF0016 family, which might be involved in active Ca transport either from the cytosol to the extracellular solution or the cytosol toward an intracellular compartment. Overall, massive Ca sequestration may have an indirect role by allowing the formation of intracellular ACC. The latter may be beneficial to the growth of the cells as a storage of inorganic C and/or a buffer of intracellular pH. Moreover, high Ca scavenging by cyanobacteria biomineralizing intracellular ACC, a trait shared with endolithic cyanobacteria, suggests that these cyanobacteria should be considered as potentially significant geochemical reservoirs of Ca.


Assuntos
Carbonato de Cálcio/metabolismo , Cálcio/metabolismo , Cianobactérias/metabolismo , Cianobactérias/crescimento & desenvolvimento , Especificidade da Espécie
7.
PLoS One ; 14(6): e0218396, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31211807

RESUMO

Microbially induced calcium carbonate precipitation (MICP) is a potential method for improvement of soil. A laboratory study was conducted to investigate the influence of temperatures for soil improvement by MICP. The ureolytic activity experiments, MICP experiments in aqueous solution and sand column using Sporosarcina pasteurii were conducted at different temperatures(10, 15, 20, 25 and 30°C). The results showed there were microbially induced CaCO3 precipitation at all the temperatures from 10 to 30°C. The results of ureolytic activity experiments showed that the bacterial had higher ureolytic activity at high temperatures within the early 20 hours, however, the ureolytic activity at higher temperatures decreased more quickly than at lower temperatures. The results of MICP experiments in aqueous solution and sand column were consistent with tests of ureolytic activity. Within 20 to 50 hours of the start of the test, more CaCO3 precipitation was precipitated at higher temperature, subsequently, the precipitation rate of all experiments decreased, and the higher the temperature, the faster the precipitation rate dropped. The final precipitation amount of CaCO3 in aqueous solution and sand column tests at 10 °C was 92% and 37% higher than that at 30 °C. The maximum unconfined compressive strength of MICP treated sand column at 10 °C was 135% higher than that at 30 °C. The final treatment effect of MICP at lower temperature was better than that at high temperature within the temperature range studied. The reason for better treatment effect at lower temperatures was due to the longer retention time of ureolytic activity of bacteria at lower temperatures.


Assuntos
Carbonato de Cálcio/química , Microbiologia do Solo , Sporosarcina/metabolismo , Carbonato de Cálcio/metabolismo , Precipitação Química/efeitos dos fármacos , Sporosarcina/química , Temperatura Ambiente , Ureia/química , Ureia/metabolismo , Água/química
8.
Poult Sci ; 98(11): 5582-5589, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31198961

RESUMO

Results from 3 experiments relating to the measurement of ileal calcium (Ca) digestibility in 4 different Ca sources for broiler chickens are presented herein. The first experiment was conducted to determine the effect of basal diet composition on the true Ca digestibility of limestone, meat and bone meal (MBM), monocalcium phosphate (MCP), and dicalcium phosphate (DCP). Eight experimental diets were developed based on 2 basal diets (corn-based or corn starch-based) with each of the 4 Ca sources. Two Ca-free diets representing both basal diets were used to determine the endogenous Ca losses. Each diet was randomly allotted to 6 replicate cages (6 birds per cage) and fed from 21 to 24 D post-hatch. Calcium digestibility of corn-based diet was higher (P < 0.05) than the corn starch-based purified diet. The average true Ca digestibility coefficients of limestone, MBM, MCP, and DCP were determined to be 0.51, 0.41, 0.43, and 0.32, respectively. The second experiment was conducted to examine the effect of indicator type on the apparent Ca digestibility of limestone. Two experimental diets with either titanium dioxide or acid insoluble ash (Celite) were developed. Each diet was randomly allotted to 6 replicate cages (8 birds per cage) and fed from 21 to 24 D post-hatch. Total tract Ca retention was also measured using the indicator ratios. Indicator type had no influence (P > 0.05) on the digestibility measurements. Ca retention determined using acid insoluble ash was higher (P < 0.05) compared to that determined using titanium dioxide. The third experiment was conducted to determine the effect of dietary adaptation length on apparent Ca digestibility of limestone. The experimental diet was offered from day 21 to 6 replicates (6 birds per cage) each for 24, 72, 120, or 168 h and the ileal digesta were collected. Calcium digestibility at 24 h was higher (P < 0.05), and increasing the adaptation length from 72 to 120 h had no effect (P > 0.05) on the digestibility.


Assuntos
Ração Animal/análise , Cálcio/fisiologia , Galinhas/fisiologia , Digestão/efeitos dos fármacos , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Carbonato de Cálcio/metabolismo , Dieta/veterinária , Íleo/fisiologia , Masculino , Distribuição Aleatória
9.
Int J Biol Macromol ; 135: 745-751, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31152837

RESUMO

Shell biomineralization is a process where inorganic minerals accumulate upon a chitinous scaffold under the control of multifunctional matrix proteins. In this study, we cloned a novel matrix protein gene from the mantle of Hyriopsis cumingii. The predicted protein, hichin, contains a chitin-binding domain and exhibited the highest expressional level in mantle tissue, with positive signals mainly detected in dorsal epithelial cells of the pallial mantle according to in situ hybridization, indicating its possible involvement in shell nacreous layer biomineralization. RNA interference showed that hichin suppression induced disordered self-assembly of the insoluble framework in the nacreous layer, and that the newly formed calcium carbonate crystals could not bind to organic frameworks. Furthermore, hichin was primarily responsible for building the framework during initial nacre deposition in pearl formation. Moreover, the chitin-binding domain of hichin also provided crystal morphology regulation in vitro crystallization assay. These results indicated that hichin is involved in the self-assembly of organic frameworks and morphological regulation in shell nacreous layer.


Assuntos
Exoesqueleto/crescimento & desenvolvimento , Carbonato de Cálcio/metabolismo , Quitina/metabolismo , Receptores de Superfície Celular/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Regulação da Expressão Gênica no Desenvolvimento , Nácar/metabolismo , Especificidade de Órgãos , RNA Mensageiro/genética , Receptores de Superfície Celular/química , Receptores de Superfície Celular/genética , Solubilidade , Unionidae
10.
Appl Microbiol Biotechnol ; 103(17): 7191-7202, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31250062

RESUMO

A low production rate for calcium carbonate with microbial solidification technology at low temperatures often restricts its application. For this reason, adding urea to the medium and the domestication of Bacillus megaterium at low temperature were proposed to produce more calcium carbonate based on an analysis of growth characteristics, urease activity, and the production rates for calcium carbonate under different conditions. Sand solidification tests were conducted to demonstrate improvements caused by the methods. The results showed that the higher the temperature, the faster the growth of Bacillus megaterium and the stronger the urease activity. Growth was fastest and urease activity strongest at a pH of 8. Adding urea to the medium and the domestication of B. megaterium at low temperature can both improve the production rate, effectively increasing calcium carbonate precipitation at low temperature. Combining the two methods resulted in greater improvement of the production rate for calcium carbonate. The two methods were also found to improve the effect of sand solidification. Therefore, our study provides a solid foundation for the actual engineering application of bio-cementation technology at low temperature.


Assuntos
Bacillus megaterium/crescimento & desenvolvimento , Bacillus megaterium/metabolismo , Biomineralização , Carbonato de Cálcio/metabolismo , Bacillus megaterium/enzimologia , Carbonato de Cálcio/química , Precipitação Química , Temperatura Baixa , Materiais de Construção/microbiologia , Meios de Cultura/química , Concentração de Íons de Hidrogênio , Ureia/análise , Ureia/metabolismo , Urease/metabolismo
11.
Bioprocess Biosyst Eng ; 42(8): 1333-1342, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31250105

RESUMO

This study investigated the factors influencing the simultaneous removal of Cd2+, NO3-N and hardness from water by the bacterial strain CN86. Optimum conditions were determined experimentally by varying the type of organic matter used, initial Cd2+ concentration, and pH. Under the optimum conditions, the maximum removal ratios of Cd2+, NO3-N and hardness were 100.00, 89.85 and 71.63%, respectively. The mechanism of Cd2+ removal is a combination of co-precipitation with calcium carbonate and pH. Further confirmation that Cd2+ can be removed by strain CN86 was provided by XRD and XPS analyses. Meteorological chromatography analysis showed that N2 was produced as an end product. These results demonstrate that the bacterial strain CN86 is a suitable candidate for simultaneously removing Cd2+, NO3-N, and hardness during in wastewater treatment.


Assuntos
Acinetobacter/crescimento & desenvolvimento , Cádmio/metabolismo , Desnitrificação , Nitratos/metabolismo , Águas Residuárias/microbiologia , Purificação da Água , Aerobiose , Cádmio/química , Carbonato de Cálcio/química , Carbonato de Cálcio/metabolismo , Nitratos/química
12.
Colloids Surf B Biointerfaces ; 181: 437-449, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31176116

RESUMO

Mesoporous vaterite CaCO3 crystals are nowadays one of the most popular vectors for loading of fragile biomolecules like proteins due to biocompatibility, high loading capacity, cost effective and simple loading procedures. However, recent studies reported the reduction of bioactivity for protein encapsulation into the crystals in water due to rather high alkaline pH of about 10.3 caused by the crystal hydrolysis. In this study we have investigated how to retain the bioactivity and control the release rate of the enzyme superoxide dismutase (SOD) loaded into the crystals via co-synthesis. SOD is widely used as an antioxidant in ophthalmology and its formulations with high protein content and activity as well as opportunities for a sustained release are highly desirable. Here we demonstrate that SOD co-synthesis can be done at pH 8.5 in a buffer without affecting crystal morphology. The synthesis in the buffer allows reaching the high loading efficiency of 93%, high SOD content (24 versus 15 w/w % for the synthesis in water), and order of magnitude higher activity compared to the synthesis in water. The enormous SOD concentration into crystals of 10-2 M is caused by the entrapment of SOD aggregates into the crystal pores. The SOD released from crystals at physiologically relevant ionic strength fully retains its bioactivity. As found by fitting the release profiles using zero-order and Baker-Lonsdale models, the SOD release mechanism is governed by both the SOD aggregate dissolution and by the diffusion of SOD molecules thorough the crystal pores. The latest process contributes more in case of the co-synthesis in the buffer because at higher pH (co-synthesis in water) the unfolded SOD molecules aggregate stronger. The release is bi-modal with a burst (ca 30%) followed by a sustained release and a complete release due to the recrystallization of vaterite crystals to non-porous calcite crystals. The mechanism of SOD loading into and release from the crystals as well as perspectives for the use of the crystals for SOD delivery in ophthalmology are discussed. We believe that together with a fundamental understanding of the vaterite-based protein encapsulation and protein release, this study will help to establish a power platform for a mild and effective encapsulation of fragile biomolecules like proteins at bio-friendly conditions.


Assuntos
Carbonato de Cálcio/metabolismo , Oftalmologia , Superóxido Dismutase/metabolismo , Carbonato de Cálcio/química , Cápsulas/química , Cápsulas/metabolismo , Cristalização , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Porosidade , Superóxido Dismutase/química , Propriedades de Superfície , Termodinâmica
13.
J Anim Sci ; 97(8): 3440-3450, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31111158

RESUMO

Two experiments were conducted to test the hypothesis that standardized total tract digestibility (STTD) of Ca and the response to microbial phytase is constant among different sources of Ca carbonate and that the STTD of Ca is constant among different sources of dicalcium phosphate (DCP) when fed to growing pigs. In Exp. 1, 80 pigs (initial BW: 19.0 ± 1.9 kg) were randomly allotted to 10 diets and 2 blocks with 4 pigs per diet in each block. Four sources of Ca carbonate were used, and each source was included in a diet without microbial phytase and a diet with microbial phytase (500 units/kg diet). Two Ca-free diets without or with microbial phytase were also formulated. Feed allowance was 2.7 times the maintenance energy requirement for ME and daily feed allotments were divided into 2 equal meals. The initial 4 d of each period were considered the adaptation period to the diets followed by 4 d of fecal collection using the marker-to-marker procedure. Pigs fed diets containing exogenous phytase had lower (P < 0.05) basal endogenous loss of Ca compared with pigs fed diets containing no phytase. There were no interactions between phytase and source of Ca carbonate. Values for STTD of Ca were greater (P < 0.05) for diets containing microbial phytase (77.3% to 85.4%) compared with diets without exogenous phytase (70.6% to 75.2%), and values for STTD of Ca differed (P < 0.05) among the 4 sources of Ca carbonate. In Exp. 2, 40 pigs (initial BW: 14.9 ± 1.3 kg) were allotted to a completely randomized design with 5 diets and 8 replicate pigs per diet. A basal diet in which all Ca was supplied by Ca carbonate was formulated. Three diets were formulated by adding 3 sources of DCP to the basal diet and a Ca-free diet was also used. Feeding and collection methods were as described for Exp. 1. Results indicated that values for STTD of Ca and ATTD of P were not different among diets, indicating that under the conditions of this experiment, the digestibility of Ca and P in DCP appears to be constant regardless of origin of DCP. In conclusion, use of microbial phytase reduces the basal endogenous loss of Ca and increases Ca digestibility in Ca carbonate. The STTD of Ca varies among sources of Ca carbonate, regardless of phytase inclusion, but that appears not to be the case for the STTD of Ca in different sources of DCP.


Assuntos
6-Fitase/farmacologia , Ração Animal/análise , Carbonato de Cálcio/metabolismo , Cálcio na Dieta/metabolismo , Suínos/metabolismo , Animais , Proteínas de Bactérias/farmacologia , Fosfatos de Cálcio/metabolismo , Dieta/veterinária , Digestão/efeitos dos fármacos , Fezes/microbiologia , Feminino , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/microbiologia , Masculino , Fósforo na Dieta/metabolismo , Distribuição Aleatória , Suínos/microbiologia
14.
Appl Microbiol Biotechnol ; 103(12): 4693-4708, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31076835

RESUMO

Biodeposition of minerals is a widespread phenomenon in the biological world and is mediated by bacteria, fungi, protists, and plants. Calcium carbonate is one of those minerals that naturally precipitate as a by-product of microbial metabolic activities. Over recent years, microbially induced calcium carbonate precipitation (MICP) has been proposed as a potent solution to address many environmental and engineering issues. However, for being a viable alternative to conventional techniques as well as being financially and industrially competitive, various challenges need to be overcome. In this review, the detailed metabolic pathways, including ammonification of amino acids, dissimilatory reduction of nitrate, and urea degradation (ureolysis), along with the potent bacteria and the favorable conditions for precipitation of calcium carbonate, are explained. Moreover, this review highlights the potential environmental and engineering applications of MICP, including restoration of stones and concrete, improvement of soil properties, sand consolidation, bioremediation of contaminants, and carbon dioxide sequestration. The key research and development questions necessary for near future large-scale applications of this innovative technology are also discussed.


Assuntos
Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Carbonato de Cálcio/metabolismo , Dióxido de Carbono/metabolismo , Precipitação Química , Aminoácidos/metabolismo , Biodegradação Ambiental , Microbiologia Ambiental , Redes e Vias Metabólicas , Solo/química , Ureia/metabolismo
15.
Nat Commun ; 10(1): 2318, 2019 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-31127116

RESUMO

Since Pasteur first successfully separated right-handed and left-handed tartrate crystals in 1848, the understanding of how homochirality is achieved from enantiomeric mixtures has long been incomplete. Here, we report on a chirality dominance effect where organized, three-dimensional homochiral suprastructures of the biomineral calcium carbonate (vaterite) can be induced from a mixed nonracemic amino acid system. Right-handed (counterclockwise) homochiral vaterite helicoids are induced when the amino acid L-Asp is in the majority, whereas left-handed (clockwise) homochiral morphology is induced when D-Asp is in the majority. Unexpectedly, the Asp that incorporates into the homochiral vaterite helicoids maintains the same enantiomer ratio as that of the initial growth solution, thus showing chirality transfer without chirality amplification. Changes in the degree of chirality of the vaterite helicoids are postulated to result from the extent of majority enantiomer assembly on the mineral surface. These mechanistic insights potentially have major implications for high-level advanced materials synthesis.


Assuntos
Asparagina/metabolismo , Carbonato de Cálcio/química , Conformação Molecular , Asparagina/química , Carbonato de Cálcio/metabolismo , Estereoisomerismo
16.
PLoS One ; 14(5): e0210231, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31063495

RESUMO

Human driven changes such as increases in oceanic CO2, global warming, petroleum hydrocarbons and heavy metals may negatively affect the ability of marine calcifiers to build their skeletons/shells, especially in polar regions. We examine spatio-temporal variability of skeletal Mg-calcite in shallow water Antarctic marine invertebrates using bryozoan and spirorbids as models in a recruitment experiment of settlement tiles in East Antarctica. Mineralogies were determined for 754 specimens belonging to six bryozoan species (four cheilostome and two cyclostome species) and two spirorbid species from around Casey Station. Intra- and interspecific variability in wt% MgCO3 in calcite among most species was the largest source of variation overall. Therefore, the skeletal Mg-calcite in these taxa seem to be mainly biologically controlled. However, significant spatial variability was also found in wt% MgCO3 in calcite, possibly reflecting local environment variation from sources such as freshwater input and contaminated sediments. Species with high-Mg calcite skeletons (e.g. Beania erecta) could be particularly sensitive to multiple stressors under predictions for near-future global ocean chemistry changes such as increasing temperature, ocean acidification and pollution.


Assuntos
Organismos Aquáticos/metabolismo , Carbonato de Cálcio/metabolismo , Magnésio/metabolismo , Esqueleto/metabolismo , Regiões Antárticas , Geografia , Análise Espaço-Temporal
17.
BMJ Case Rep ; 12(4)2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30948398

RESUMO

A 35-year-old woman presented to the surgical clinic complaining of right hypochondrial pain for 4 days. Abdominal examination revealed tenderness on deep palpation in the right hypochonrdium, with no palpable organs or masses. The patient had repeated attacks of the same pain that mandated repeated admissions to the emergency hospital and treated conservatively. The white blood cell count was 13 000 cells/µL. Ultrasound examination of the abdomen showed thick-walled gall bladder, thick bile, with no visible stones and acalculous cholecystitis was the diagnosis. Decision done for laparoscopic cholecystectomy. After removal of the gall bladder and opening the bladder, a thick milky contents was found to fill the gall bladder with no stones. The diagnosis of limy bile syndrome then done. Histopathological examination of the gall bladder showed features of chronic cholecystitis with no malignancy. The patient discharged on the third postoperative day with no complications.


Assuntos
Colecistite Acalculosa/etiologia , Bile/química , Carbonato de Cálcio/metabolismo , Colecistite Aguda/etiologia , Doenças do Ducto Colédoco/metabolismo , Adulto , Doenças do Ducto Colédoco/complicações , Feminino , Humanos , Síndrome
18.
Curr Med Sci ; 39(2): 337-342, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31016531

RESUMO

Calcium carbonates are commonly administered as supplements for conditions of calcium deficiency. We report here pharmacokinetic characteristics of a novel formulation, calcium carbonate compound granules (CCCGs), forming complexes of calcium carbonate and calcium citrate in water. CCCGs were compared to a kind of commonly-used calcium carbonate D3 preparation (CC) in the market in 5-week-old mice that had been treated with omeprazole, to suppress gastric acid secretion, and in untreated control mice. The results showed that: (1) CCCGs had better water solubility than CC in vitro; (2) In control mice, calcium absorption rates after CCCGs administration were comparable to those after CC administration; (3) Inhibition of gastric acid secretion did not affect calcium absorption after CCCGs, but moderately decreased it after CC; (4) The presence of phytic acid or tannin did not affect calcium absorption rates after CCCGs but did for CC; and (5) In normal mice, CCCGs did not inhibit gastric emptying and intestinal propulsion, and did not alter the gastrointestinal hormones. The results suggest that CCCGs may be therapeutically advantageous over more commonly used calcium supplement formulations, particularly for adolescents, because of their stable calcium absorption characteristics and their relatively favorable adverse effect profile.


Assuntos
Carbonato de Cálcio/metabolismo , Ácido Gástrico/metabolismo , Animais , Cálcio na Dieta/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL
19.
Fish Shellfish Immunol ; 89: 437-447, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30980916

RESUMO

Proteinase inhibitors with the ability to inhibit specific proteinases are usually closely connected with the immune system. Interestingly, proteinase inhibitors are also a common ingredient in the organic matrix of mollusk shells. However, the molecular mechanism that underlies the role of proteinase inhibitors in immune system and shell mineralization is poorly known. In this study, a Kunitz serine proteinase inhibitor (HcKuPI) was isolated from the mussel Hyriopsis cumingii. HcKuPI was specifically expressed in dorsal epithelial cells of the mantle pallium and HcKuPI dsRNA injection caused an irregular surface and disordered deposition on the aragonite tablets of the nacreous layer. These results indicated that HcKuPI plays a vital role in shell nacreous layer biomineralization. Moreover, the expression pattern of HcKuPI during LPS challenge and pearl formation indicated its involvement in the antimicrobial process during pearl sac formation and nacre tablets accumulation during pearl formation. In the in vitro calcium carbonate crystallization assay, the addition of GST-HcKuPI increased the precipitation rate of calcium carbonate and induced the crystal overgrowth of calcium carbonate. Taken together, these results indicate that HcKuPI is involved in antimicrobial process during pearl formation, and participates in calcium carbonate deposition acceleration and morphological regulation of the crystals during nacreous layer formation. These findings extend our knowledge of the role of proteinase inhibitors in immune system and shell biomineralization.


Assuntos
Antibacterianos/metabolismo , Carbonato de Cálcio/metabolismo , Nácar/metabolismo , Inibidores de Proteases , Unionidae/genética , Unionidae/imunologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Inibidores de Proteases/química , Inibidores de Proteases/metabolismo , Unionidae/metabolismo
20.
Sci Total Environ ; 672: 722-731, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30974362

RESUMO

Microbial induced carbonate precipitation (MICP) is a natural bio-mediated process, which has been explored for soil stabilization and heavy metals immobilization in soil and groundwater. Previous studies have shown that MICP is capable of immobilizing various heavy metals including lead (Pb). However, most studies focus merely on the immobilization of heavy metals with relatively low concentration. This study: (1) presents results of an investigation into the toxic effects of Pb on bacterial activity and immobilization efficiency within a wide range of Pb concentrations; and (2) identifies controlling biotic and abiotic factors of Pb immobilization by MICP. In the first series of tests, bacterial strains (Sporosarcina pasteurii) are inoculated into nutrient solutions containing 0-50 mM Pb(NO3)2 and incubated at 30 °C. Biochemical parameters are measured over time, which include pH, electrical conductivity, urease activity, and viable cell number. In the second series of tests, grown bacterial strains are mixed with urea, calcium salts and Pb(NO3)2 in solution. Viable cell number, produced ammonium concentration, aqueous Pb concentration of the mixed solution, and total precipitation mass are measured. The results show that the presence of Pb has marginal effect on bacterial growth and associated urease activity at Pb concentration < 30 mM. The calcium source and initial bacteria concentration are found to remarkably influence Pb immobilization efficiency in terms of Pb removal percentage. Supplementary geochemical simulation results indicate that the Pb immobilization mechanisms includes abiotic precipitation, biotic precipitation and bio-sorption.


Assuntos
Bactérias/efeitos dos fármacos , Chumbo/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Bactérias/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Carbonato de Cálcio/metabolismo , Água Subterrânea , Metais Pesados , Solo
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