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Journal ArticleDOI

Magnesium-induced biofilm development in Arthrobacter sp. SUK 1201 and removal of hexavalent chromium

22 Jun 2018-Soil and Sediment Contamination: An International Journal (Taylor & Francis)-Vol. 27, Iss: 5, pp 383-392
TL;DR: Both Scanning and Confocal Laser Scanning Microscopy revealed that biofilms formed under the induction of Mg(II) had characteristic higher cell densities, suggesting its possible implication in effective bioremediation of chromium polluted environments.
Abstract: This study reports the influence of Mg ions on the development and architecture of biofilms by a chromium resistant and reducing bacterium Arthrobacter sp. SUK 1201 and their utilization in the removal of toxic hexavalent chromium. Among the different metal ions tested, Mg(II) greatly influenced the biofilm growth in peptone yeast extract glucose medium. Both Scanning and Confocal Laser Scanning Microscopy revealed that biofilms formed under the induction of Mg(II) had characteristic higher cell densities. The cells remain embedded in thick porous layers of extracellular polymeric substances as evident from the fluorescein isothiocyanate labeled lectin concanavalin A and 4, 6- diamino-2-phenylindole staining. COMSTAT analysis also indicated maximum thickness and roughness coefficient of the biofilm grown in presence of Mg(II). Biofilms of Arthrobacter sp. SUK 1201 developed under such Mg (II) influenced condition showed complete removal of 0.5 mM Cr(VI) in mineral salts medium. The biofilm of this...
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TL;DR: A link between SprV and an ∼67-kDa protein in the culture supernatant of strain UA159 that was later confirmed as SMU.63 was established, and it was discovered that SprV downregulates the transcription and translation of SM U.63 in S. mutans.
Abstract: In Streptococcus mutans, SprV (SMU.2137) is a pleiotropic regulator that differentially regulates genes related to competence, mutacin production, biofilm formation, and the stress tolerance response, along with some other pathways. In this study, we established a link between SprV and an ∼67-kDa protein in the culture supernatant of strain UA159 that was later confirmed as SMU.63 by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis. We discovered that SprV downregulates the transcription and translation of SMU.63. We found that the seven amino acids from the C-terminal region of SprV were also crucial for the expression of SMU.63. Deletion of smu.63 led to increased sucrose-independent biofilm formation and competence. The sprV deletion also increased biofilm formation although this could be partially attributed to the downregulation of smu.63. In an smu.63 sprV double mutant, a synergistic effect was observed in biofilm formation in contrast to effects on competence development. We found that low or excess magnesium ion repressed sprV transcription that, in turn, affected the expression of smu.63. As expected, a magnesium ion-dependent effect of competence and biofilm formation was observed in the UA159 strain. We also replicated the results of SMU.63 expression and competence in S. mutans GS5 that encodes both SprV and SMU.63 homologs and found that the GS5 strain behaves similarly to the UA159 strain, indicating that SprV’s effect is strain independent. IMPORTANCE We previously identified a pleiotropic regulator, SprV, in Streptococcus mutans. This regulator appears to be highly conserved among streptococci. Here, we showed that SprV regulates the expression of a secreted protein encoded by SMU.63 in S. mutans. SMU.63 has been known to impact biofilm formation and genetic competence, two important characteristics that help in colonization of the organism. SMU.63 is also unique since it is known to form amyloid fiber. We found that SprV regulates the expression of SMU.63 at both the transcriptional and translational levels. We also found that the expression of SprV is regulated by magnesium ion concentration. Interestingly, both low and high magnesium ion concentrations affected biofilm formation and genetic competence. Since SMU.63 is also highly conserved among streptococci, we hypothesized that SprV will have a similar effect on its expression.

4 citations


Cites background from "Magnesium-induced biofilm developme..."

  • ..., both chromium (Cr) and nickel (Ni), in addition to Mg, can induce biofilm formation (51, 52)....

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Journal ArticleDOI
TL;DR: The present investigation was carried out to delineate the microbial diversity of rhizosphere soil using metagenomic approach, and Bacillus, Pseudomonas and Staphylococcus demonstrated abundant presence in this soil.

2 citations

01 Jan 2013
TL;DR: In this article, an indigenous chromium-resistant bacterial strain (A 8 ) was identified as Cellulosimicrobium sp. on the basis of morphological and biochemical characterization and 16S rRNA gene sequencing.
Abstract: Cr(VI) is a toxic metal that has carcinogenic and mutagenic effects on all living organisms. In order to study the contribution of microbes towards Cr(VI) reduction into the less toxic Cr(III) form, an indigenous chromium-resistant bacterial strain (A 8 ) was isolated from a tannery effluent. It was identified as Cellulosimicrobium sp. on the basis of morphological and biochemical characterization and 16S rRNA gene sequencing. It could tolerate up to 1800 µg mL -1 of K 2 CrO 4 and showed an optimum reduction (98.6%) of Cr(VI) at the concentration of 900 µg mL -1 aerobically. Cell-free enzyme assay exhibited the reduction of Cr(VI) in vitro. A total of 4 synthetic materials, sand, PVC, stone, and rubber tubing, were used as solid support to evaluate the ability of the isolated chromium-resistant bacterial strain for biofilm formation. In column experiments among bacterial film-coated materials, sand exhibited an excellent Cr(VI) reduction (96%), while PVC pipe, rubber tubing, and stone showed 94.5%, 90%, and 88.4% reduction potential of Cr(VI), respectively, after 96 h of incubation. Fluorescent microscopy also revealed that bacterial biofilm was distributed thoroughly on the surface of the sand particles. FTIR spectroscopy showed mainly the involvement of the glycerol units, polysaccharides, and C-N (alkyl) functional groups of the bacterial strain (A 8 ) in the reduction of Cr(VI).
Journal ArticleDOI
TL;DR: The study showed that the divalent cations magnesium and calcium increased biofilm formation compared with the monovalent cation, sodium, which did not have a significant effect on the initial stages ofBiofilm formation but appeared to influence the later stages of biofilm development.
Abstract: Abstract Listeria monocytogenes is a gram-positive foodborne pathogen that causes outbreaks of listeriosis associated with a diverse range of foods. L. monocytogenes forms biofilms as a strategy to enhance its survival in the environment. These biofilms then provide a source of contamination in processing plant environments. Cations like magnesium, calcium, and sodium are commonly found in the environment and are important to bacteria to maintain their homeostasis. It is, therefore, valuable to understand the relationship between these cations and biofilm formation. In this study, four isolates of L. monocytogenes from seafood processing environments were used to investigate the influence of magnesium, calcium, and sodium (1, 10, and 50 mM) on biofilms. The isolates selected were defined as being either a low biofilm former, a high biofilm former, an outbreak isolate, and a persistent isolate from the seafood industry. The study showed that the divalent cations magnesium and calcium increased biofilm formation compared with the monovalent cation, sodium. Fifty mM concentrations of the divalent cations significantly enhanced biofilm formation. The cations did not have a significant effect on the initial stages of biofilm formation but appeared to influence the later stages of biofilm development.
References
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Journal Article
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.

289,852 citations


"Magnesium-induced biofilm developme..." refers methods in this paper

  • ...The protein, DNA and RNA contents were estimated following Lowry et al. (1951), diphenylamine method (Burton et al. 1956) and orcinol method (Plummer et al. 1988) respectively....

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Journal ArticleDOI
TL;DR: In this article, a method was developed to determine submicro amounts of sugars and related substances using a phenol-sulfuric acid reaction, which is useful for the determination of the composition of polysaccharides and their methyl derivatives.
Abstract: Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color w-hen treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.

45,381 citations


"Magnesium-induced biofilm developme..." refers methods in this paper

  • ...The pellet was then dissolved in distilled water and quantified following the method of Dubois et al. (1956)....

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Journal ArticleDOI
K. Burton1
TL;DR: The present study arose from the observation that a more intense colour was sometimes produced if, instead of being heated at 1000 for 10 min., the reaction mixture was allowed to stand overnight at room temperature.
Abstract: Of the colour reactions available for the determination and identification of deoxyribonucleic acid (DNA), the reaction with diphenylamine in a mixture of acetic and sulphuric acids at 1000 (Dische, 1930) has been perhaps the most widely used. The present study arose from the observation that a more intense colour was sometimes produced if, instead of being heated at 1000 for 10 min., the reaction mixture was allowed to stand overnight at room temperature. As a result of this observation the procedure has been modified, principally by adding acetaldehyde to the reagents and by allowing the solution to stand for about 17 hr. at 30° instead of heating it at 1000. The modified method is 3-5 times as sensitive as Dische's original procedure, and several substances which interfere in the original method do not do so in the modified procedure. Some observations on the mechanism of the reaction have been made; in particular it was discovered that there is a liberation of inorganic orthophosphate from DNA during the early stages of the reaction. This finding has a bearing on the structure of DNA. The modified method has already been used in an investigation of nucleic acid metabolism during bacteriophage multiplication (Burton, 1955).

13,649 citations

Journal ArticleDOI
TL;DR: The functions, properties and constituents of the EPS matrix that make biofilms the most successful forms of life on earth are described.
Abstract: The microorganisms in biofilms live in a self-produced matrix of hydrated extracellular polymeric substances (EPS) that form their immediate environment. EPS are mainly polysaccharides, proteins, nucleic acids and lipids; they provide the mechanical stability of biofilms, mediate their adhesion to surfaces and form a cohesive, three-dimensional polymer network that interconnects and transiently immobilizes biofilm cells. In addition, the biofilm matrix acts as an external digestive system by keeping extracellular enzymes close to the cells, enabling them to metabolize dissolved, colloidal and solid biopolymers. Here we describe the functions, properties and constituents of the EPS matrix that make biofilms the most successful forms of life on earth.

7,041 citations


"Magnesium-induced biofilm developme..." refers background or methods in this paper

  • ...Chemically, the matrix is constituted of proteins, glycoproteins, polysaccharides, lipids, phospholipids, humic acids and nucleic acids (Flemming and Wingender 2010) depending on the microbial species and the environmental conditions....

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  • ...The biofilm EPS was extracted by warm water treatment (Flemming and Wingender 2010)....

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Journal ArticleDOI
TL;DR: Analysis of biofilms of P. aureofaciens growing on 0.03 mM, 0.1 mM or 0.5 mM citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration, whereas surface to volume ratio increased with higher citrate concentrations.
Abstract: The structural organization of four microbial communities was analysed by a novel computer program, COMSTAT, which comprises ten features for quantifying three-dimensional biofilm image stacks. Monospecies biofilms of each of the four bacteria, Pseudomonas putida, P. aureofaciens, P. fluorescens and P. aeruginosa, tagged with the green fluorescent protein (GFP) were grown in flow chambers with a defined minimal medium as substrate. Analysis by the COMSTAT program of four variables describing biofilm structure ‐ mean thickness, roughness, substratum coverage and surface to volume ratio ‐ showed that the four Pseudomonas strains represent different modes of biofilm growth. P. putida had a unique developmental pattern starting with single cells on the substratum growing into micro-colonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form micro-colonies. Finally, the biofilm structures of P. fluorescens had a phenotype intermediate between those of P. putida and P. aureofaciens. Analysis of biofilms of P. aureofaciens growing on 0<03 mM, 0< 1m M or 0< 5m M citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration. Moreover, biofilm roughness increased with lower citrate concentrations, whereas surface to volume ratio increased with higher citrate concentrations.

1,952 citations


"Magnesium-induced biofilm developme..." refers methods in this paper

  • ...Different biofilm parameters including total biomass, roughness coefficient, average surface area, area to biomass ratio and biofilm thickness were analyzed from the CSLM images using COMSTAT software....

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  • ...Biofilm parameters including average thickness, maximum thickness, total biomass, average surface area of biomass in each image stack, surface to biovolume ratio and roughness coefficient of the image stacks were analyzed using COMSTAT (Heydorn et al. 2000) and quantified....

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