Structure and carbohydrate analysis of the exopolysaccharide capsule of <i>Pseudomonas putida</i> G7

Kachlany, Scott C.; Levery, Steven B.; Kim, John S.; Reuhs, Bradley L.; Lion, Leonard W.; Ghiorse, William C.

doi:10.1046/j.1462-2920.2001.00248.x

Cited by 113 publications

(65 citation statements)

References 54 publications

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“…2B); this was supported by scanning electron microscopy (SEM) analysis of biofilm cells on the filters which showed cells associated with rope-like structures, consistent with SEM analysis of mesophilic biofilms (Fig. 2C) (22,24,40).…”

Section: Resultssupporting

confidence: 74%

Transcriptional Analysis of Biofilm Formation Processes in the Anaerobic, Hyperthermophilic BacteriumThermotoga maritima

Pysz

Conners

Montero

et al. 2004

Appl Environ Microbiol

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Thermotoga maritima, a fermentative, anaerobic, hyperthermophilic bacterium, was found to attach to bioreactor glass walls, nylon mesh, and polycarbonate filters during chemostat cultivation on maltose-based media at 80°C. A whole-genome cDNA microarray was used to examine differential expression patterns between biofilm and planktonic populations. Mixed-model statistical analysis revealed differential expression (twofold or more) of 114 open reading frames in sessile cells (6% of the genome), over a third of which were initially annotated as hypothetical proteins in the T. maritima genome. Among the previously annotated genes in the T. maritima genome, which showed expression changes during biofilm growth, were several that corresponded to biofilm formation genes identified in mesophilic bacteria (i.e., Pseudomonas species, Escherichia coli, and Staphylococcus epidermidis). Most notably, T. maritima biofilm-bound cells exhibited increased transcription of genes involved in iron and sulfur transport, as well as in biosynthesis of cysteine, thiamine, NAD, and isoprenoid side chains of quinones. These findings were all consistent with the up-regulation of iron-sulfur cluster assembly and repair functions in biofilm cells. Significant up-regulation of several ␤-specific glycosidases was also noted in biofilm cells, despite the fact that maltose was the primary carbon source fed to the chemostat. The reasons for increased ␤-glycosidase levels are unclear but are likely related to the processing of biofilm-based polysaccharides. In addition to revealing insights into the phenotype of sessile T. maritima communities, the methodology developed here can be extended to study other anaerobic biofilm formation processes as well as to examine aspects of microbial ecology in hydrothermal environments.

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Section: Resultssupporting

confidence: 74%

Transcriptional Analysis of Biofilm Formation Processes in the Anaerobic, Hyperthermophilic BacteriumThermotoga maritima

Pysz

Conners

Montero

et al. 2004

Appl Environ Microbiol

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“…The stringy rope features observed in the SEM images ( Fig. 2A and B) indicate the presence of a biofilm that has been desiccated during sample preparation (25). The TEM results suggest that the Mn precipitate is closely associated with the cells and is composed of small, wafer-shaped particles (Fig.…”

Section: Bacterial Growth and Mn Oxidationmentioning

confidence: 94%

Spatially Resolved Characterization of Biogenic Manganese Oxide Production within a Bacterial Biofilm

Toner¹,

Fakra

Villalobos

et al. 2005

Appl Environ Microbiol

135

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Pseudomonas putida strain MnB1, a biofilm-forming bacterial culture, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of aqueous Mn ؉2 [Mn ؉2(aq) ] by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm, using scanning transmission X-ray microscopy (STXM) combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Mn L 2,3 absorption edges. Subsamples were collected from growth flasks containing 0.1 and 1 mM total Mn at 16, 24, 36, and 48 h after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at a 40-nm resolution. Manganese NEX-AFS spectra were extracted from X-ray energy sequences of STXM images (stacks) and fit with linear combinations of well-characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III), and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn ؉2 (aq) was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission X-ray microscopy is a promising tool for advancing the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.The chemistry of many aqueous environments is dictated by reactions that occur at the interface between the aqueous solution phase and the solid mineral and organic phases (43). It is at this interface that microorganisms also accumulate (4, 14). Microorganisms are known to form layered communities (biofilms) characterized by production of extracellular polymers, in which the physical and chemical conditions may differ greatly from those of the bulk solution. Within the biofilm setting, microorganisms carry out dissolution and precipitation of minerals, exerting direct influence on the cycling of trace and contaminant metals alike (18,51).In particular, the precipitation of manganese (Mn) in soils, sediments, and water columns is primarily driven by microbial activity (11,18,33). Although conditions are thermodynamically favorable for the oxidation of aqueous Mn ϩ2 [Mn ϩ2 (aq) ] in the presence of dissolved oxygen, the homogeneous (reaction involving only solution-phase reactants) kinetics of oxidation are slow (32). Rates of Mn oxidation observed in natural waters are often too high to be attributed to homogeneous or surface-mediated reactions (32). Microbial processes are thought to control the precipitation and dissolution of Mn oxides in many natural systems, and Mn-oxidizing microorganisms have been isolated ...

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“…Extracellular polymeric substances produced by many microorganisms are of particular relevance to the bioremediation process because of their involvement in fl occulation and binding of metal ions from solutions [56,57]. The use of isolated biopolymers in biosorption phenomenon seems to be more economical, effective and safe alternative to chemical methods such as precipitation, coagulation, ion exchange, electrochemical and membrane processes.…”

Section: Interactions Of Eps With Heavy Metalsmentioning

confidence: 99%

Microbial extracellular polymeric substances: central elements in heavy metal bioremediation

2008

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Extracellular polymeric substances (EPS) of microbial origin are a complex mixture of biopolymers comprising polysaccharides, proteins, nucleic acids, uronic acids, humic substances, lipids, etc. Bacterial secretions, shedding of cell surface materials, cell lysates and adsorption of organic constituents from the environment result in EPS formation in a wide variety of free-living bacteria as well as microbial aggregates like biofi lms, biofl ocs and biogranules. Irrespective of origin, EPS may be loosely attached to the cell surface or bacteria may be embedded in EPS. Compositional variation exists amongst EPS extracted from pure bacterial cultures and heterogeneous microbial communities which are regulated by the organic and inorganic constituents of the microenvironment. Functionally, EPS aid in cell-to-cell aggregation, adhesion to substratum, formation of fl ocs, protection from dessication and resistance to harmful exogenous materials. In addition, exopolymers serve as biosorbing agents by accumulating nutrients from the surrounding environment and also play a crucial role in biosorption of heavy metals. Being polyanionic in nature, EPS forms complexes with metal cations resulting in metal immobilization within the exopolymeric matrix. These complexes generally result from electrostatic interactions between the metal ligands and negatively charged components of biopolymers. Moreover, enzymatic activities in EPS also assist detoxifi cation of heavy metals by transformation and subsequent precipitation in the polymeric mass. Although the core mechanism for metal binding and / or transformation using microbial exopolymer remains identical, the existence and complexity of EPS from pure bacterial cultures, biofi lms, biogranules and activated sludge systems differ signifi cantly, which in turn affects the EPS -metal interactions. This paper presents the features of EPS from various sources with a view to establish their role as central elements in bioremediation of heavy metals.

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Structure and carbohydrate analysis of the exopolysaccharide capsule of Pseudomonas putida G7

Cited by 113 publications

References 54 publications

Transcriptional Analysis of Biofilm Formation Processes in the Anaerobic, Hyperthermophilic BacteriumThermotoga maritima

Transcriptional Analysis of Biofilm Formation Processes in the Anaerobic, Hyperthermophilic BacteriumThermotoga maritima

Spatially Resolved Characterization of Biogenic Manganese Oxide Production within a Bacterial Biofilm

Microbial extracellular polymeric substances: central elements in heavy metal bioremediation

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