Effect of urea concentration on microbial Ca precipitation (original) (raw)
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Biogeosciences, 2014
Microbial-induced CaCO 3 precipitation (MICP) is an innovative technique that harnesses bacterial activity for the modification of the physical properties of soils. Since stimulation of MICP by urea hydrolysis in natural soils is likely to be affected by interactions between ureolytic and non-ureolytic bacteria, we designed an experiment to examine the interactions between ureolytic and non-ureolytic bacteria and the effect of these interactions on MICP. An artificial groundwater-based rich medium was inoculated with two model species of bacteria, the ureolytic species Sporosarcina pasteurii and the non-ureolytic species Bacillus subtilis. The control treatment was inoculated with a pure culture of S. pasteurii. The following parameters were monitored during the course of the experiment: optical density, pH, the evolution of ammonium, dissolved calcium and dissolved inorganic carbon. The results showed that dissolved calcium was precipitated as CaCO 3 faster in the mixed culture than in the control, despite less favorable chemical conditions in the mixed culture, i.e., lower pH and lower CO 2− 3 concentration. B. subtilis exhibited a considerably higher growth rate than S. pasteurii, resulting in higher density of bacterial cells in the mixed culture. We suggest that the presence of the non-ureolytic bacterial species, B. subtilis, accelerated the MICP process, via the supply of nucleation sites in the form of non-ureolytic bacterial cells.
Journal of Microbiological Methods, 2013
Two bacterial strains, Pseudomonas aeruginosa MJK1 and Escherichia coli MJK2, were constructed that both express green fluorescent protein (GFP) and carry out ureolysis. These two novel model organisms are useful for studying bacterial carbonate mineral precipitation processes and specifically ureolysis-driven microbially induced calcium carbonate precipitation (MICP). The strains were constructed by adding plasmid-borne ure-ase genes (ureABC, ureD and ureFG) to the strains P. aeruginosa AH298 and E. coli AF504gfp, both of which already carried unstable GFP derivatives. The ureolytic activities of the two new strains were compared to the common, non-GFP expressing, model organism Sporosarcina pasteurii in planktonic culture under standard laboratory growth conditions. It was found that the engineered strains exhibited a lower ureolysis rate per cell but were able to grow faster and to a higher population density under the conditions of this study. Both engineered strains were successfully grown as biofilms in capillary flow cell reactors and ureolysis-induced calcium carbonate mineral precipitation was observed microscopically. The undisturbed spatiotem-poral distribution of biomass and calcium carbonate minerals were successfully resolved in 3D using confocal laser scanning microscopy. Observations of this nature were not possible previously because no obligate urease producer that expresses GFP had been available. Future observations using these organisms will allow researchers to further improve engineered application of MICP as well as study natural mineralization processes in model systems. Microbially induced calcium carbonate precipitation (MICP) is an important process in many engineered and natural systems including: geologic carbon sequestration, radionuclide remediation, soil stabilization and permeability manipulation (
Strain-Specific Ureolytic Microbial Calcium Carbonate Precipitation
Applied and Environmental Microbiology, 2003
During a study of ureolytic microbial calcium carbonate (CaCO 3 ) precipitation by bacterial isolates collected from different environmental samples, morphological differences were observed in the large CaCO 3 crystal aggregates precipitated within bacterial colonies grown on agar. Based on these differences, 12 isolates were selected for further study. We hypothesized that the striking differences in crystal morphology were the result of different microbial species or, alternatively, differences in the functional attributes of the isolates selected. Sequencing of 16S rRNA genes showed that all of the isolates were phylogenetically closely related to the Bacillus sphaericus group. Urease gene diversity among the isolates was examined by using a novel application of PCR-denaturing gradient gel electrophoresis (DGGE). This approach revealed significant differences between the isolates. Moreover, for several isolates, multiple bands appeared on the DGGE gels, suggesting the apparent presence of different urease genes in these isolates. The substrate affinities (K m ) and maximum hydrolysis rates (V max ) of crude enzyme extracts differed considerably for the different strains. For certain isolates, the urease activity increased up to 10-fold in the presence of 30 mM calcium, and apparently this contributed to the characteristic crystal formation by these isolates. We show that strain-specific calcification occurred during ureolytic microbial carbonate precipitation. The specificity was mainly due to differences in urease expression and the response to calcium.
Microorganisms
Microbiologically induced CaCO3 precipitation (MICP) is a well-known bio-based solution with application in environmental, geotechnical, and civil engineering. The significance of the MICP has increased explorations of process efficiency and specificity via natural bacterial isolates. In this study, comprehensive profiling of five soil ureolytic Bacillus strains was performed through a newly formed procedure that involved six steps from selection and identification, through kinetic study, to the characterization of the obtained precipitates, for the first time. To shorten the whole selection procedure of 43 bioagents with the MICP potential, Standard Score Analysis was performed and five selected bacteria were identified as Bacillus muralis, B. lentus, B. simplex, B. firmus, and B. licheniformis by the MALDI-TOF mass spectrometry. Despite following the targeted activity, kinetic studies were included important aspects of ureolysis and the MICP such as cell concentration, pH profilin...
Calcium Carbonate Precipitation by Urease and Carbonic Anhydrase Positive Bacteria
Pamukkale University Journal of Engineering Sciences
In present study, CaCO3 precipitation was examined in two ureolytic bacteria. Bacillus aerius U2 and Sporosarcina pasteurii ATCC 6453 were used as test organisms. The determination of urease and carbonic anhydrase enzyme activities were also determined. For further confirmation of the calcium carbonate mineral type produced by bacteria, XRD, SEM and EDX analysis were done. Strain U2 produced calcite and vaterite. In S. pasteurii ATCC 6453, only vaterite was found. The enzyme activity studies showed that both urease and carbonic anhydrase activities was 2-50-fold higher in S. pasteurii ATCC 6453 than B. aerius U2. Although, S. pasteurii ATCC 6453 was better option for microbial calcium carbonate precipitation (MCP) at higher temperature, by B. aerius U2 at lower temperature (<30 °C) is made possible to employ in the most geotechnical applications. Bu çalışmada, iki üreolitik bakteride CaCO3 çökelimi araştırılmıştır. Test organizması olarak Bacillus aerius U2 ve Sporosarcina pasteurii ATCC 6453 türleri kullanılmıştır. Bunların yanında, bakterilerin üreaz ve karbonik anhidraz enzim aktiviteleri de tespit edilmiştir. Bakteriler tarafından üretilen kalsiyum karbonatın mineral tipi konformasyonu için XRD, SEM ve EDX analizleri gerçekleştirilmiştir. B. aerius U2 suşu kalsit ve vaterit üretmiştir. S. pasteurii ATCC 6453 suşunda sadece vaterit bulunmuştur. Enzim aktivitesi çalışmalarının sonuçlarına göre S. pasteurii ATCC 6453, B. aerius U2'den 2-50 kat daha fazla aktivite göstermiştir. Yüksek sıcaklıklarda kalsiyum karbonat çökelimi için S. pasteurii ATCC 6453 türü tercih edilebilirken, daha geniş iklim bölgelerini kapsayan düşük sıcaklıklarda(<30 °C) B. aerius U2 türünün kullanım potansiyeli bulunmaktadır.
Defence life science journal, 2022
The current study was designed to isolate and characterize urease-producing bacteria and to assess their ability to precipitate calcium carbonate. Total eight bacteria were isolated from dung-rich soil samples collected from Dakor, Gujarat. Out of these, two bacterial strains designated as DGDK-3 and DGDK-4 were found to produce a considerable level of urease in the initial screening on the urea agar medium. Based on morphological and physiological tests and more specifically by 16S rRNA gene sequencing analysis, these bacteria were identified as Quasibacillus sp. Strain DGDK-3 and Bacillus sp. Strain DGDK-4. The strains DGDK-3 and DGDK-4 showed 25 IU/ml and 89 IU/ ml urease activity, respectively. Also, the efficacy of both strains was tested for calcium carbonate precipitation. Results showed that both the isolates were competent to precipitate a significant level of calcium carbonate. The current work demonstrated that urease-producing bacteria can be utilised in bio-cementationas a crack sealing agent and as a natural stabilizing agent.
Advances in Materials Science and Engineering, 2015
Calcium carbonate is a widely used raw material by many industries. It can be precipitated through microbial process within soil pores as cementitious bonding agent between grains for geotechnical applications. It is called microbially induced calcium carbonate precipitation (MICP). Designing an appropriate biogrout material for injection into soil is essential for controlling the amount, type, time, and place of the biocement production within pores. For this purpose, understanding the active reactions and the kinetics of bacterial growth and urea hydrolysis is necessary. A conductometric method and spectrophotometry were used in this study to, respectively, monitor the urea hydrolysis reaction progress and bacterial growth inS. pasteurii-inoculated urea-NB-NH4Cl solution at different level of the environmental factors that are initial cell concentration, urea concentration, and temperature. Variation in conductivity of the solution versus logarithmic scale of time was depicted as ...
Carbon isotope fractionation during calcium carbonate precipitation induced by ureolytic bacteria
Geochimica et Cosmochimica Acta, 2012
et aux énergies alternatives, Direction des sciences de la matière, IRaMis/SIS2M/LAPA, a b s t r a c t Stable carbon isotopic fractionation during calcium carbonate precipitation induced by urease-catalysed hydrolysis of urea was experimentally investigated in artificial water at a constant temperature of 30°C. Carbon isotope fractionation during urea hydrolysis follows a Rayleigh distillation trend characterized by a 13 C-enrichment factor of −20 to −22‰. CaCO 3 precipitate is up to 17.9‰ 13 C-depleted relative to the urea substrate (−48.9±0.07‰). Initial CaCO 3 precipitate forms close to isotopic equilibrium with dissolved inorganic carbon. Subsequent precipitation occurs at −2 to −3‰ offset from isotopic equilibrium, suggesting that the initial δ 13 C value of CaCO 3 is reset through dissolution followed by reprecipitation with urease molecules playing a role in offsetting the δ 13 C value of CaCO 3 from isotopic equilibrium. Potentially, this isotopic systematics may provide a tool for the diagnosis of ureolytically-formed carbonate cements used as sealing agent. Moreover, it may serve as a basis to develop a carbon isotope tool for the quantification of ureolytically-induced CO 2 sequestration. Finally, it suggests carbon isotope disequilibrium as a hallmark of past enzymatic activity in ancient microbial carbonate formation.