Microbially induced calcium carbonate precipitation through CO2 sequestration via an engineered Bacillus subtilis.

BACKGROUND: Microbially induced calcium carbonate precipitation has been extensively researched for geoengineering applications as well as diverse uses within the built environment. Bacteria play a crucial role in producing calcium carbonate minerals, via enzymes including carbonic anhydrase-an enzyme with the capability to hydrolyse CO2, commonly employed in carbon capture systems. This study describes previously uncharacterised carbonic anhydrase enzyme sequences capable of sequestering CO2 and subsequentially generating CaCO3 biominerals and suggests a route to produce carbon negative cementitious materials for the construction industry. RESULTS: Here, Bacillus subtilis was engineered to recombinantly express previously uncharacterised carbonic anhydrase enzymes from Bacillus megaterium and used as a whole cell catalyst allowing this novel bacterium to sequester CO2 and convert it to calcium carbonate. A significant decrease in CO2 was observed from 3800 PPM to 820 PPM upon induction of carbonic anhydrase and minerals recovered from these experiments were identified as calcite and vaterite using X-ray diffraction. Further experiments mixed the use of this enzyme (as a cell free extract) with Sporosarcina pasteurii to increase mineral production whilst maintaining a comparable level of CO2 sequestration. CONCLUSION: Recombinantly produced carbonic anhydrase successfully sequestered CO2 and converted it into calcium carbonate minerals using an engineered microbial system. Through this approach, a process to manufacture cementitious materials with carbon sequestration ability could be developed.

Microbiologically induced calcite precipitation (MICP) in situ remediated heavy metal contamination in sludge nutrient soil.

Microbiologically induced calcite precipitation (MICP), as a newly developing bioremediation technology, could redeem heavy metal contamination in diverse scenarios. In this study, MICP bacterium Sporosarcina ureilytica ML-2 was employed to suppress the pollution of Pb, Cd and Zn in municipal sludge nutrient soil. After MICP remediation, the exchangeable Cd and Zn in sludge nutrient soil were correspondingly reduced by 31.02 % and 6.09 %, while the carbonate-bound Pb, Cd and Zn as well as the residual fractions were increased by 16.12 %, 6.63 %, 13.09 % and 6.10 %, 45.70 %, 3.86 %, respectively. In addition, the extractable Pb, Cd and Zn either by diethylenetriaminepentaacetic acid (DTPA) or toxicity characteristic leaching procedure (TCLP) in sludge nutrient soil were significantly reduced. These results demonstrated that the bio-calcite generated via MICP helped to immobilize heavy metals. Furthermore, MICP treatment improved the abundance of functional microorganisms related to urea cycle, while reduced the overall abundance of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs). This work confirmed the feasibility of MICP in remediation of heavy metal in sludge nutrient soil, which expanded the application field of MICP and provided a promising way for heavy metal pollution management.

Sporosarcina jeotgali sp. nov., Sporosarcina oncorhynchi sp. nov., and Sporosarcina trichiuri sp. nov., Isolated from Jeotgal, a Traditional Korean Fermented Seafood.

Three novel, Gram-stain-positive, obligate aerobic, catalase- and oxidase-positive bacterial strains, designated B2O-1T, T2O-4T, and 0.2-SM1T-5T, were isolated from jeotgal, a traditional Korean fermented seafood. Strains B2O-1T, T2O-4T, and 0.2-SM1T-5T exhibited distinct colony colors, characterized by pink, yellow, and red opaque circular colonies, respectively. Phylogenetic analysis revealed that three strains formed a paraphyletic clade within the genus Sporosarcina and shared < 99.0% similarity with Sporosarcina aquimarina KCTC 3840T and Sporosarcina saromensis KCTC 13119T in their 16S rRNA gene sequences. The three strains exhibiting Orthologous Average Nucleotide Identity values < 79.3% and digital DNA-DNA hybridization values < 23.1% within the genus Sporosarcina affirmed their distinctiveness. Strains B2O-1T, T2O-4T, and 0.2-SM1T-5T contained MK-7 as a sole respiratory menaquinone and A4α type peptidoglycan based on lysine with alanine, glutamic acid, and aspartic acid. The common polar lipids include diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. Strain T2O-4T contained one unidentified phospholipid, whereas strain 0.2-SM1T-5T contained two unidentified phospholipids. Cellular fatty acid profiles, with C15:0 anteiso as the major fatty acid, supported the affiliation of the three strains to the genus Sporosarcina. Based on the polyphasic characteristics, strains B2O-1T (= KCTC 43506T = JCM 36032T), T2O-4T (= KCTC 43489T = JCM 36031T), and 0.2-SM1T-5T (= KCTC 43519T = JCM 36034T) represent three novel species within the genus Sporosarcina, named Sporosarcina jeotgali sp. nov., Sporosarcina oncorhynchi sp. nov., and Sporosarcina trichiuri sp. nov., respectively.

Taxonomic and genomic characterization of Sporosarcina cyprini sp. nov., moderately tolerant of Cr+6 and Cd+2 isolated from the gut of invasive fish Cyprinus carpio var. communis (Linn., 1758).

A Gram-stain-positive, motile, and rod-shaped bacterium, designated as strain MB25T, was isolated from the gut of Cyprinus carpio from the highly polluted river Yamuna, India. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain MB25T belonged to the genus Sporosarcina, sharing the highest sequence similarity with S. luteola Y1T (98.98%) and S. koreensis S-K12T (98.91%). Digital DNA-DNA hybridization and average nucleotide identity values of strain MB25T with strain Y1T and S-K12T were 18.9, 77.69, and 18.2, 76.80 respectively. Genome analysis of strain MB25T revealed its biotechnological properties such as tolerance to potent heavy metals, genes for the production of carbohydrate-active enzymes, antimicrobial compounds, and also degradation of aromatic compounds. The G + C content of strain MB25T genome was 45%. Growth observed at 10-40 °C (optimum, 28-30 °C), pH 6.0-8.5 (optimum pH 7.5-8.0); NaCl concentrations up to 6.0% (w/v). The dominant respiratory quinone was MK-7, cell wall peptidoglycan is of the A-4 type containing amino acids Lys-Glu and the major fatty acids are anteiso-C11:0 and iso-C15: 0. The major polar lipids of strain MB25T are diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. On the basis of phenotypic, chemotaxonomic, phylogenetic, and phylogenomic data, strain MB25T represents a novel species of the genus Sporosarcina, for which the name Sporosarcina cyprini sp. nov. is proposed. The type strain is MB25T (= MCC 4366 T = JCM 34521 T = CCM 9113 T).

Sporosarcina beigongshangi sp. nov., isolated from pit mud of Baijiu.

A Gram-positive, aerobic and short rod-shaped bacterium designated REN13T, was isolated from pit mud of Baijiu, in Sichuan province, China. Strain REN13T could grow at 10-50 â„ƒ, pH 6.0-9.0 and 0-2% (w/v) NaCl, with the optimal growth occurred at 28 â„ƒ, pH 7.0, and 2% (w/v) NaCl. 16S rRNA gene sequence analysis showed that strain REN13T was closely related to Sporosarcina globispora DSM 4T (98.6%). The DNA G + C content of strain REN13T was 41.1 mol %. DDH and ANI value between strain REN13T and S. globispora DSM 4T was 24.4% and 67.6%, respectively. The major fatty acids were iso-C15:0 and antesio-C15:0. The respiratory quinone was MK-7, and the polar lipids were phosphatidylethanolamine, phospholipids, phosphatidylglycerol and diphosphatidylglycerol. Based on the above polyphasic taxonomic analysis, strain REN13T represents a novel species of the genus Sporosarcina, for which the name Sporosarcina beigongshangi sp. nov. is proposed. The type strain is strain REN13T (= JCM 34409T = GDMCC 1.2151T).

Exploring the Cr(VI) removal mechanism of Sporosarcina saromensis M52 from a genomic perspective.

Serious hexavalent chromium [Cr(VI)] pollution has continuously threatened ecological security and public health. Microorganism-assisted remediation technology has strong potential in the treatment of environmental Cr(VI) pollution due to its advantages of high efficiency, low cost, and low secondary pollution. Sporosarcina saromensis M52, a strain with strong Cr(VI) removal ability, isolated from coastal intertidal zone was used in this study. Scanning electron microscopy coupled with energy dispersive X-ray analysis indicated M52 was relatively stable under Cr(VI) stress and trace amount of Cr deposited on the cell surface. X-ray photoelectron spectroscopy and X-ray diffraction analyses exhibited M52 could reduce Cr(VI) into Cr(III). Fourier transform infrared spectroscopy showed the bacterial surface was mainly consisted of polysaccharides, phosphate groups, carboxyl groups, amide II (NH/CN) groups, alkyl groups, and hydroxyl groups, while functional groups involving in Cr(VI) bio-reduction were not detected. According to these characterization analyses, the removal of Cr(VI) was primarily depended on bio-reduction, instead of bio-adsorption by M52. Genome analyses further indicated the probable mechanisms of bio-reduction, including the active efflux of Cr(VI) by chromate transporter ChrA, enzymatic redox reactions mediated by reductases, DNA-repaired proteases ability to minimize the ROS damage, and the formation of specific cell components to minimize the biofilm injuries caused by Cr(VI). These studies provided a theoretical basis which was useful for Cr(VI) remediation, especially in terms of increasing its effectiveness. THE MAIN FINDING OF THE WORK: M52 realized the bioremediation of Cr(VI) majorly through bio-reduction, including Cr(VI) efflux, chromate reduction, DNA repair, and the formation of specific cell components, instead of bio-adsorption.

Improvement of Biomineralization of Sporosarcina pasteurii as Biocementing Material for Concrete Repair by Atmospheric and Room Temperature Plasma Mutagenesis and Response Surface Methodology.

Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45°C, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.

Transcriptome analyses reveal the utilization of nitrogen sources and related metabolic mechanisms of Sporosarcina pasteurii.

In recent years, Sporosarcina pasteurii (S. pasteurii) has become one of the most popular bacteria in microbially induced calcium carbonate precipitation (MICP). Various applications have been developed based on the efficient urease that can induce the precipitation of calcium carbonate. However, the metabolic mechanism related to biomineralization of S. pasteurii has not been clearly elucidated. The process of bacterial culture and biomineralization consumes a large amount of urea or ammonium salts, which are usually used as agricultural fertilizers, not to mention probable environmental pollutions caused by the excessive use of these raw materials. Therefore, it is urgent to reveal the mechanism of nitrogen utilization and metabolism of S. pasteurii. In this paper, we compared the growth and gene expression of S. pasteurii under three different culture conditions through transcriptome analyses. GO and KEGG analyses revealed that both ammonium and urea were direct nitrogen sources of S. pasteurii, and the bacteria could not grow normally in the absence of ammonium or urea. To the best of our knowledge, this paper is the first one to reveal the nitrogen utilization mechanism of S. pasteurii through transcriptome methods. Furthermore, the presence of ammonium might promote the synthesis of intracellular ATP and enhance the motility of the bacteria. There should be an ATP synthesis mechanism associated with urea hydrolysis catalyzed by urease in S. pasteurii.

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii.

BACKGROUND: The ureolytic bacterium Sporosarcina pasteurii is well-known for its capability of microbially induced calcite precipitation (MICP), representing a great potential in constructional engineering and material applications. However, the molecular mechanism for its biomineralization remains unresolved, as few studies were carried out. RESULTS: The addition of urea into the culture medium provided an alkaline environment that is suitable for S. pasteurii. As compared to S. pasteurii cultivated without urea, S. pasteurii grown with urea showed faster growth and urease production, better shape, more negative surface charge and higher biomineralization ability. To survive the unfavorable growth environment due to the absence of urea, S. pasteurii up-regulated the expression of genes involved in urease production, ATPase synthesis and flagella, possibly occupying resources that can be deployed for MICP. As compared to non-mineralizing bacteria, S. pasteurii exhibited more negative cell surface charge for binding calcium ions and more robust cell structure as nucleation sites. During MICP process, the genes for ATPase synthesis in S. pasteurii was up-regulated while genes for urease production were unchanged. Interestingly, genes involved in flagella were down-regulated during MICP, which might lead to poor mobility of S. pasteurii. Meanwhile, genes in fatty acid degradation pathway were inhibited to maintain the intact cell structure found in calcite precipitation. Both weak mobility and intact cell structure are advantageous for S. pasteurii to serve as nucleation sites during MICP. CONCLUSIONS: Four factors are demonstrated to benefit the super performance of S. pasteurii in MICP. First, the good correlation of biomass growth and urease production of S. pasteurii provides sufficient biomass and urease simultaneously for improved biomineralization. Second, the highly negative cell surface charge of S. pasteurii is good for binding calcium ions. Third, the robust cell structure and fourth, the weak mobility, are key for S. pasteurii to be nucleation sites during MICP.

Study of As-resistant bacteria from Nadia, India and a survey of two As resistance-related proteins.

The present investigation deals with the characterisation of three As-resistant bacteria, Bacillus aryabhattai strain VPS1, Bacillus licheniformis strain VPS6 and Sporosarcina thermotolerans strain VPS7 isolated from the rhizosphere of a contaminated paddy field in Chakdaha, Nadia, West Bengal, India. Two strains, VPS6 and VPS7 showed ureolytic activity, which can be used for microbial-induced calcite precipitation of As as a bioremediation option. However, As reduction and oxidation capacities were not reported in any of these bacteria. A phylogenetic tree of 16S ribosomal RNA gene sequences was constructed for all three bacterial isolates, including different species of As-resistant Bacillus and Sporosarcina. Furthermore, literature survey and genome mining were employed to explore the diversity of As resistance-related proteins, arsenite S-adenosylmethyltransferase (ArsM) and arsenical pump membrane protein (ArsB) among different bacteria, and the phylogenetic relatedness was studied to understand the distribution and evolution of their amino acid sequences. ArsB was predominantly present in a wide variety of bacteria (347 taxa); however, ArsM was reported in comparatively fewer isolates (109 taxa). There were a total of 60 similar taxa that contained both ArsM and ArsB. Both proteins were most abundantly present in phylum Proteobacteria. Overall, this investigation enumerates As-resistant bacteria to understand the As metabolism in the environment, and the phylogenetic analysis of As resistance-related proteins helps in understanding the functional relationship in different bacteria for their role in As mobility in the environment.

Facultative and anaerobic consortia of haloalkaliphilic ureolytic micro-organisms capable of precipitating calcium carbonate.

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.

Rational Control of Calcium Carbonate Precipitation by Engineered Escherichia coli.

Ureolytic bacteria ( e.g., Sporosarcina pasteurii) can produce calcium carbonate (CaCO3). Tailoring the size and shape of biogenic CaCO3 may increase the range of useful applications for these crystals. However, wild type Sporosarcina pasteurii is difficult to genetically engineer, limiting control of the organism and its crystal precipitates. Therefore, we designed, constructed, and compared different urease operons and expression levels for CaCO3 production in engineered Escherichia coli strains. We quantified urease expression and calcium uptake and characterized CaCO3 crystal phase and morphology for 13 engineered strains. There was a weak relationship between urease expression and crystal size, suggesting that genes surrounding the urease gene cluster affect crystal size. However, when evaluating strains with a wider range of urease expression levels, there was a negative relationship between urease activity and polycrystal size (e.g., larger crystals with lower activity). The resulting range of crystal morphologies created by the rationally designed strains demonstrates the potential for controlling biogenic CaCO3 precipitation.

Comparative genomics of cocci-shaped Sporosarcina strains with diverse spatial isolation.

BACKGROUND: Cocci-shaped Sporosarcina strains are currently one of the few known cocci-shaped spore-forming bacteria, yet we know very little about the genomics. The goal of this study is to utilize comparative genomics to investigate the diversity of cocci-shaped Sporosarcina strains that differ in their geographical isolation and show different nutritional requirements. RESULTS: For this study, we sequenced 28 genomes of cocci-shaped Sporosarcina strains isolated from 13 different locations around the world. We generated the first six complete genomes and methylomes utilizing PacBio sequencing, and an additional 22 draft genomes using Illumina sequencing. Genomic analysis revealed that cocci-shaped Sporosarcina strains contained an average genome of 3.3 Mb comprised of 3222 CDS, 54 tRNAs and 6 rRNAs, while only two strains contained plasmids. The cocci-shaped Sporosarcina genome on average contained 2.3 prophages and 15.6 IS elements, while methylome analysis supported the diversity of these strains as only one of 31 methylation motifs were shared under identical growth conditions. Analysis with a 90% identity cut-off revealed 221 core genes or ~ 7% of the genome, while a 30% identity cut-off generated a pan-genome of 8610 genes. The phylogenetic relationship of the cocci-shaped Sporosarcina strains based on either core genes, accessory genes or spore-related genes consistently resulted in the 29 strains being divided into eight clades. CONCLUSIONS: This study begins to unravel the phylogenetic relationship of cocci-shaped Sporosarcina strains, and the comparative genomics of these strains supports identification of several new species.

Sporosarcina terrae sp. nov., isolated from orchard soil.

A Gram-stain-positive, motile and rod-shaped bacterium, designated strain LZ2T, was isolated from a sample of orchard soil from Laizhou city, Shandong province, PR China. On the basis of 16S rRNA gene sequence analysis, strain LZ2T was closely related to members of the genus Sporosarcina, sharing highest levels of sequence similarity with Sporosarcina pasteurii NCIMB 8841T (98.8 %), Sporosarcina soli I80T (95.9 %). The value for the DNA-DNA relatedness between strain LZ2T and Sporosarcina pasteurii NCIMB 8841T was 39.8±1.7 %. Growth occurred at 10-44 °C (optimum, 30-35 °C), pH 5.0-11.0 (optimum pH 9.0-10.0); NaCl concentrations of up to 7.0 % (w/v) were tolerated. The dominant respiratory quinone was MK-7 and the G+C content was 39.2 mol%. The major fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The major polar lipids of strain LZ2T were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid. Based on phenotypic and chemotaxonomic characteristics, and phylogenetic data strain LZ2T represents a novel species of the genus Sporosarcina, for which the name Sporosarcina terrae sp. nov. (type strain LZ2T=KACC 18822T=MCCC 1K03174T) is proposed.

A bacterial acyl aminoacyl peptidase couples flexibility and stability as a result of cold adaptation.

Life in cold environments requires an overall increase in the flexibility of macromolecular and supramolecular structures to allow biological processes to take place at low temperature. Conformational flexibility supports high catalytic rates of enzymes in the cold but in several cases is also a cause of instability. The three-dimensional structure of the psychrophilic acyl aminoacyl peptidase from Sporosarcina psychrophila (SpAAP) reported in this paper highlights adaptive molecular changes resulting in a fine-tuned trade-off between flexibility and stability. In its functional form SpAAP is a dimer, and an increase in flexibility is achieved through loosening of intersubunit hydrophobic interactions. The release of subunits from the quaternary structure is hindered by an 'arm exchange' mechanism, in which a tiny structural element at the N terminus of one subunit inserts into the other subunit. Mutants lacking the 'arm' are monomeric, inactive and highly prone to aggregation. Another feature of SpAAP cold adaptation is the enlargement of the tunnel connecting the exterior of the protein with the active site. Such a wide channel might compensate for the reduced molecular motions occurring in the cold and allow easy and direct access of substrates to the catalytic site, rendering transient movements between domains unnecessary. Thus, cold-adapted SpAAP has developed a molecular strategy unique within this group of proteins: it is able to enhance the flexibility of each functional unit while still preserving sufficient stability. DATABASE: Structural data are available in the Protein Data Bank under the accession number 5L8S.

Truncation Derivatives of the S-Layer Protein of Sporosarcina ureae ATCC 13881 (SslA): Towards Elucidation of the Protein Domain Responsible for Self-Assembly.

The cell surface of Sporosarcina ureae ATCC 13881 is covered by an S-layer (SslA) consisting of identical protein subunits that assemble into lattices exhibiting square symmetry. In this work the self-assembly properties of the recombinant SslA were characterised with an emphasis on the identification of protein regions responsible for self-assembly. To this end, recombinant mature SslA (aa 31-1097) and three SslA truncation derivatives (one N-terminal, one C-terminal and one CN-terminal) were produced in a heterologous expression system, isolated, purified and their properties analysed by in vitro recrystallisation experiments on a functionalised silicon wafer. As a result, recombinant mature SslA self-assembled into crystalline monolayers with lattices resembling the one of the wild-type SslA. The study identifies the central protein domain consisting of amino acids 341-925 self-sufficient for self-assembly. Neither the first 341 amino acids nor the last 172 amino acids of the protein sequence are required to self-assemble into lattices.

Biosequestration of copper by bacteria isolated from an abandoned mine by using microbially induced calcite precipitation.

Abandoned mine sites are frequently polluted with high concentrations of heavy metals. In this study, 25 calcite-forming bacteria were newly isolated from the soil of an abandoned metal mine in Korea. Based on their urease activity, calcite production, and resistance to copper toxicity, four isolates were selected and further identified by 16S rRNA gene sequencing. Among the isolates, Sporosarcina soli B-22 was selected for subsequent copper biosequestration studies, using the sand impermeability test by production of calcite and extracellular polymeric substance. High removal rates (61.8%) of copper were obtained when the sand samples were analyzed using an inductively coupled plasma-optical emission spectrometer following 72 h of incubation. Scanning electron microscopy showed that the copper carbonate precipitates had a diameter of approximately 5-10 µm. X-ray diffraction further confirmed the presence of copper carbonate and calcium carbonate crystals.

Complete genome sequence of the Sporosarcina psychrophila DSM 6497, a psychrophilic Bacillus strain that mediates the calcium carbonate precipitation.

Sporosarcina psychrophila DSM 6497 is a gram positive, spore-formation psychrophilic bacterial strain, widely distributed in terrestrial and aquatic environments. Here we report its complete sequence including one circular chromosome of 4674191bp with a GC content of 40.3%. Genes encoding urease are predicted in the genome, which provide insight information on the microbiologically mediated urea hydrolysis process. This urea hydrolysis can further lead to an increase of carbonate anion and alkalinity in the environment, which promotes the microbiologically induced carbonate precipitation with various applications, such as the bioremediation of calcium rich wastewater and bio-reservation of architectural patrimony.

Bioremediation of Hexavalent Chromium Pollution by Sporosarcina saromensis M52 Isolated from Offshore Sediments in Xiamen, China.

OBJECTIVE: Cr(VI) removal from industrial effluents and sediments has attracted the attention of environmental researchers. In the present study, we aimed to isolate bacteria for Cr(VI) bioremediation from sediment samples and to optimize parameters of biodegradation. METHODS: Strains with the ability to tolerate Cr(VI) were obtained by serial dilution and spread plate methods and characterized by morphology, 16S rDNA identification, and phylogenetic analysis. Cr(VI) was determined using the 1,5-diphenylcarbazide method, and the optimum pH and temperature for degradation were studied using a multiple-factor mixed experimental design. Statistical analysis methods were used to analyze the results. RESULTS: Fifty-five strains were obtained, and one strain (Sporosarcina saromensis M52; patent application number: 201410819443.3) having the ability to tolerate 500 mg Cr(VI)/L was selected to optimize the degradation conditions. M52 was found be able to efficiently remove 50-200 mg Cr(VI)/L in 24 h, achieving the highest removal efficiency at pH 7.0-8.5 and 35 °C. Moreover, M52 could completely degrade 100 mg Cr(VI)/L at pH 8.0 and 35 °C in 24 h. The mechanism involved in the reduction of Cr(VI) was considered to be bioreduction rather than absorption. CONCLUSION: The strong degradation ability of S. saromensis M52 and its advantageous functional characteristics support the potential use of this organism for bioremediation of heavy metal pollution.

Extracellular synthesis of silver and gold nanoparticles by Sporosarcina koreensis DC4 and their biological applications.

The present study highlights the microbial synthesis of silver and gold nanoparticles by Sporosarcina koreensis DC4 strain, in an efficient way. The synthesized nanoparticles were characterized by ultraviolet-visible spectrophotometry, which displayed maximum absorbance at 424nm and 531nm for silver and gold nanoparticles, respectively. The spherical shape of nanoparticles was characterized by field emission transmission electron microscopy. The energy dispersive X-ray spectroscopy and elemental mapping were displayed the purity and maximum elemental distribution of silver and gold elements in the respective nanoproducts. The X-ray diffraction spectroscopy results demonstrate the crystalline nature of synthesized nanoparticles. The particle size analysis demonstrate the nanoparticles distribution with respect to intensity, volume and number of nanoparticles. For biological applications, the silver nanoparticles have been explored in terms of MIC and MBC against pathogenic microorganisms such as Vibrio parahaemolyticus, Escherichia coli, Salmonella enterica, Bacillus anthracis, Bacillus cereus and Staphylococcus aureus. Moreover, the silver nanoparticles in combination with commercial antibiotics, such as vancomycin, rifampicin, oleandomycin, penicillin G, novobiocin, and lincomycin have been explored for the enhancement of antibacterial activity and the obtained results showed that 3µg concentration of silver nanoparticles sufficiently enhance the antimicrobial efficacy of commercial antibiotics against pathogenic microorganism. Furthermore, the silver nanoparticles potential has been reconnoitered for the biofilm inhibition by S. aureus, Pseudomonas aeruginosa and E. coli and the results revealed sufficient activity at 6µg concentration. In addition, gold nanoparticles have been applied for catalytic activity, for the reduction of 4-nitrophenol to 4-aminophenol using sodium borohydride and positive results were attained.