Browsing by Author "Quintero, Ernesto J."

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Adhesion of biofilms to inert surfaces: a molecular level approach directed at the marine environments
(1996-09) Baty, Ace M.; Frolund, B.; Geesey, Gill G.; Langille, S. E.; Quintero, Ernesto J.; Suci, Peter A.; Weiner, R. M.
Protein/ligand interactions involved in mediating adhesion between microorganisms and biological surfaces have been well‐characterized in some cases (e.g. pathogen/host interactions). The strategies microorganisms employ for attachment to inert surfaces have not been so clearly elucidated. An experimental approach is presented which addresses the issues from the point of view of molecular interactions occurring at the interface.
Adhesive extracellular polymers of hyphomonas mhs-3: interaction of polysaccharides and proteins
(1995-12) Suci, Peter A.; Frolund, B.; Quintero, Ernesto J.; Weiner, R. M.; Geesey, Gill G.
The adsorption behavior of extracellular polymeric substances (EPS) from the marine bacterium Hyphomonas MHS‐3 was investigated using attenuated total reflection Fourier transform infrared (ATR/FT‐IR) spectrometry. The protein fraction of the crude EPS (EPSC) (propanol precipitated/extracted with EDTA) dominated the adsorption onto the germanium substratum. Removal of the Protease K accessible portion of the EPSC protein, and treatment with RNase and DNase, yielded a hygroscopic substance (EPSP) which contained at least one adhesive polysaccharide component. Conditioning the substratum with EPSC diminished adsorption of the polysaccharide fractions in EPSP; pre‐adsorbed EPSC protein was not displaced. The rate of EPSC adsorption on substrata conditioned with EPSP was slower than to clean germanium; however, the projected surface coverage of protein after long times, based on an empirical datafit, was the same as that for a clean substratum; the EPSC proteins did not displace the pre‐adsorbed adhesive polysaccharide fraction. SDS‐PAGE (Coomassie blue stain) revealed an extensive homology between proteins from cell lysates and EPSC proteins. However, distinct differences in the banding pattern suggested that proteins did not originate primarily from cell lysis during the extraction procedure. The results indicate that adhesive components of EPS, with respect to a hydrophilic surface (germanium), can be either protein or polysaccharide and that they may compete for interfacial binding sites.
Comparison of reduction methods for gas chromatography/mass spectrometry identification and quantitation of uronic acids in acidic polysaccharides
(1989-06) Quintero, Ernesto J.; Ishida, Kenneth P.; Gordon, Grisel; Geesey, Gill G.
Four different reduction procedures were evaluated for their efficiency in dideuterating uronic acids in acidic polysaccharides. A method using 8 M urea to dissolve the polymers and 1-chyclohexyl-3-(2-morpholinoethyl)-carbodiimide metho-p-toluene sulfonate (CMC) to form uronide esters provided the best uronide dideuteration and uronic acid and neutral hexose sugar recoveries. Of the total uronic acid detected by a colorimetric assay, 20–30% was recovered as specific uronic acids from low-viscosity biopolymers by gas chromatography—mass spectrometry when this reduction procedure was employed. Lower and more variable recoveries of uronic acids were obtained from high-viscosity polysaccharides. The technique provided positive identification of the uronic acids in all five acidic polymers tested, even when the polymer also contained the corresponding neutral sugar analogue. Although quantitative recovery of uronic acids was not obtained, the technique nevertheless provides useful information on the relative contribution of uronic acids and neutral sugars in unpurified low-viscosity polymer preparations.
Function of bacterial (hyphomonas spp.) capsular exopolymers in biofouling
(1997) Weiner, R. M.; Langille, S. E.; Geesey, Gill G.; Quintero, Ernesto J.
The osmotic coefficients of the sodium form of some polymers of biological origin
(1989-08) Jang, Larry K.; Quintero, Ernesto J.; Gordon, Grisel; Röhricht, Markus; Geesey, Gill G.
The osmotic coefficients ϕp,Na of dilute solutions of the sodium form of some weakly acidic polymers are theoretically predicted in this work. Based on the measured value 0.73 of γNa, the activity coefficient of free Na+, of the completely ionized humic acid (sodium salt) in a salt-free solution, the effective interligand distance b is calculated to be 11.34 Å by using Manning's counterion condensation theory [Manning, G. S. (1969) J. Chem. Phys.51(3), 924]. The corresponding values of γNa (measured experimentally) and b for the completely ionized exopolymer of Pseudomonas atlantica are 0.624 and 7.57 Å when cultivated at a dilution rate D = 0.015 h−1, 0.647 and 8.19 Å at D = 0.025 h−1, and 0.613 and 7.29 Åat D = 0.06 h−1. For alginic acid (in the completely ionized sodium form), γNa = 0.40 and b = 4.71 Å. The osmotic coefficients ϕp,Nafor the partially and the completely ionized polymers are then predicted with Manning's theory as well.
A sensitive chromatographic method for the detection of pyruvyl groups microbial polymers from sediments
(1990-03) Smith, James J.; Quintero, Ernesto J.; Geesey, Gill G.
A method was developed for the quantitation of pyruvyl groups in microbial polymers using mild acid hydrolysis, o-phenylenediamine labeling, reversed-phase high-performance liquid chromatography (RP-HPLC), and fluorescence detection. The method was used to determine the pyruvate content of various microbial exopolysaccharides and to estimate the abundance of polymeric pyruvate in freshwater sediments. The results of this method were compared with those of several other pyruvate assays. The detection limit of the method was 1.6 nmol pyruvate. As little as 3.7μg of the bacterial polysaccharide xanthan gum, or from 5 to 22 mg of sediment (depending on polymeric pyruvate content), were needed for detection and quantitation of polymeric pyruvate. The results should be useful in determining the contribution of polymeric pyruvate to total metal-binding ligands in sediments.