Microenvironments of pH in biofilms grown on dissolving silicate surfaces

Liermann, Laura J.; Barnes, Arthur K.; Kalinowski, Birgitta E.; Zhou, Xiangyang; Brantley, Susan L.

doi:10.1016/s0009-2541(00)00202-3

Cited by 83 publications

(42 citation statements)

References 32 publications

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“…This amount is much higher in the case of mixed liquor sludge (Figure 6), although the quantity of the sludge solids was lower compared to the case of solid sludge experiment (Figure 7). This corroborates the explanation given above that the centrifugation possibly destroys the bacterial cell wall and releases acid groups from the inner cells of the sludge to the solution (Liermann et al, 2000). …”

Section: Acid-base Behavior and Determination Of Suspension Chargesupporting

confidence: 91%

“…This is almost one unit of pH lower than the pzc value determined for the mixed liquor. This difference between the pzc value of the solid and MLSS can be explained by the fact that centrifugation possibly destroys the bacterial cell wall and releases acid groups from the inner cell to the solution (Liermann et al, 2000). This is in accordance with the fact that dead cells exhibit lower values of iep, and thus pzc.…”

Section: Potentiometric Mass Titration Of Activated Sludgesupporting

confidence: 62%

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The use of Potentiometric Mass Titration (PMT) technique for determining the acid-base behavior of activated sludge

2015

Global NEST Journal

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Activated sludge is a biological floc composed of microorganisms, organics, and inorganics and plays an important role in wastewater treatment. The pH of an activated sludge suspension determines the acid -base behavior and the charge of the microorganisms in water. In the present study, the determination of acid -base behavior of activated sludge was performed using microelectrophoresis and Potentiometric Mass Titrations (PMT). For activated sludge that is a complicated biological system, direct microelectrophoresis is not a suitable method for the determination of its ζ-potential. This method leads to a variety of isoelectric point (iep) values due to the presence of different microorganisms in activated sludge. On the contrary, the PMT method used for the first time for activated sludge can provide the overall point of zero charge (pzc) value that is 8.2. In addition, a simple methodology is proposed for the quantitative determination of the overall solid charge as a function of solution pH, which requires only (a) the titration curves of an electrolyte suspension and of the blank electrolyte solution and (b) the calculation of the H + ions consumed for the above titration curves.

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Section: Acid-base Behavior and Determination Of Suspension Chargesupporting

confidence: 91%

Section: Potentiometric Mass Titration Of Activated Sludgesupporting

confidence: 62%

The use of Potentiometric Mass Titration (PMT) technique for determining the acid-base behavior of activated sludge

2015

Global NEST Journal

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“…Indirectly, they affect weathering rates by complexing ions in solution, thus lowering the solution saturation rate (34). The production of organic acid anions by bacterial strains was related to the weathering of hornblende (35) and the mobilization of metals from carbonates and oxides (13). In the present study, oxalate production seems to have an important role in the solubilization of Mn and Ni.…”

Section: Discussionsupporting

confidence: 52%

Bacterially Induced Weathering of Ultramafic Rock and Its Implications for Phytoextraction

Becerra-Castro

Kidd

Kuffner

et al. 2013

Appl Environ Microbiol

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The bioavailability of metals in soil is often cited as a limiting factor of phytoextraction (or phytomining). Bacterial metabolites, such as organic acids, siderophores, or biosurfactants, have been shown to mobilize metals, and their use to improve metal extraction has been proposed. In this study, the weathering capacities of, and Ni mobilization by, bacterial strains were evaluated. Minimal medium containing ground ultramafic rock was inoculated with either of two Arthrobacter strains: LA44 (indole acetic acid [IAA] producer) or SBA82 (siderophore producer, PO 4 solubilizer, and IAA producer). Trace elements and organic compounds were determined in aliquots taken at different time intervals after inoculation. Trace metal fractionation was carried out on the remaining rock at the end of the experiment. The results suggest that the strains act upon different mineral phases. LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides, and this appeared to be related to oxalate production. SBA82 also leads to release of Ni and Mn, albeit to a much lower extent. In this case, the concurrent mobilization of Fe and Si indicates preferential weathering of Fe oxides and serpentine minerals, possibly related to the siderophore production capacity of the strain. The same bacterial strains were tested in a soil-plant system: the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain. At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots. Ni yield was significantly enhanced in plants inoculated with LA44. These results suggest that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants.

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“…The nutrient content of mineral surfaces drives the attachment (Bennett et 62 al., 1996a;Brisou, 1995;Madigan et al, 2000). In fact, in environments depleted in one or more 63 among crystals, preferential dissolution of inclusions or along crystal grain boundaries), glass 135 planchets were synthesized with a composition similar to the Fe-silicate mineral hornblende 136 (Liermann et al, 2000a) …”

Section: Surface Colonization 51mentioning

confidence: 99%

Etch pit formation on iron silicate surfaces during siderophore-promoted dissolution

2007

Self Cite

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Understanding the effects of microbiota on mineral alteration requires the ability to recognize evidence of bacteria-promoted dissolution on mineral surfaces. Although siderophores are known to promote mineral dissolution, their effects on mineral surfaces are not well known. We have utilized atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Mirau vertical scanning interferometry (VSI) to investigate surfaces after incubation with the siderophore desferrioxamine-B mesylate (DFAM) and under colonies of bacteria. Iron-silicate glass planchets chemically similar to hornblende were incubated in buffered growth medium with siderophore-producing bacteria (Bacillus sp.) for 46 days with parallel abiotic experiments conducted with and without 240 μM DFAM, with and without 0.01 g/l of microbially produced extracellular polysaccharides (EPS, alginate or xanthan gum). Some glass planchets were protected by dialysis tubing from direct contact with the EPS. Weekly sampling and analysis of all filtered sample solutions showed negligible Fe and Al release in the control experiments and significant release of Fe and Al in the presence of DFAM, with negligible changes in pH. Concentration of Fe in the filtered solutions after incubation with bacteria was below detection, consistent with uptake of Fe by cells. Release of Fe, Al, and Si in control, xanthan-only, and alginate-only experiments was negligible. Release of these elements was enhanced in all experiments containing DFAM, and greatest in alginate + DFAM experiments. AFM and VSI analyses reveal widespread, small etch pits and greater root mean squared roughness on siderophore-exposed surfaces and fewer, localized, larger etch pits on bacteria-exposed surfaces. This is the first documented case of etch pit development during siderophore-promoted dissolution. Roughness was not affected by growth medium or alginate or xanthan gum alone. The roughness trends among samples correlate with trends in Fe depletion documented by XPS. Enhanced dissolution and roughness cannot be attributed to direct contact with EPS because no significant chemical or physical differences were observed between surfaces directly exposed to EPS and those protected by dialysis tubing. Acetate released from the EPS may have enhanced the siderophore-promoted dissolution. Siderophores produced by Bacillus sp. may be responsible for some of the 'biopits.' The difference in size and distribution of the biopits may be related to colonization. AFM and VSI analyses reveal widespread, small etch pits and greater root mean squared 36 roughness on siderophore-exposed surfaces and fewer, localized, larger etch pits on bacteria-37 exposed surfaces. This is the first documented case of etch pit development during siderophore-38 promoted dissolution. Roughness was not affected by the growth medium, alginate, or xanthan 39 gum alone. The roughness trends among samples correlate with trends in Fe depletion 40 2 documented by XPS. Enhanced dissolution and roughness cannot be attributed t...

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Microenvironments of pH in biofilms grown on dissolving silicate surfaces

Cited by 83 publications

References 32 publications

The use of Potentiometric Mass Titration (PMT) technique for determining the acid-base behavior of activated sludge

The use of Potentiometric Mass Titration (PMT) technique for determining the acid-base behavior of activated sludge

Bacterially Induced Weathering of Ultramafic Rock and Its Implications for Phytoextraction

Etch pit formation on iron silicate surfaces during siderophore-promoted dissolution

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