Determination of bacterial growth and activity at solid-liquid interfaces.
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Bacteria↗
Biomedical subjects
G G Geesey
Publications and source records attributed to G G Geesey.
The osmotic coefficients of the sodium form of some biopolymers.
The osmotic coefficients phi p,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 gamma Na, 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 A by using Manning's counterion condensation theory [Manning, G. S. (1969) J. Chem. Phys. 51(3), 924]. The corresponding values of gamma Na (measured experimentally) and b for the completely ionized exopolymer of Pseudomonas atlantica are 0.624 and 7.57 A when cultivated at a dilution rate D = 0.015 h-1, 0.647 and 8.19 A at D = 0.025 h-1, and 0.613 and 7.29 Aat D = 0.06 h-1. For alginic acid (in the completely ionized sodium form), gamma Na = 0.40 and b = 4.71 A. The osmotic coefficients phi p,Na for the partially and the completely ionized polymers are then predicted with Manning's theory as well.
Biopolymers↗
Bacterial biofilms in nature and disease.
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Animals↗
Copper-binding characteristics of exopolymers from a freshwater-sediment bacterium.
Copper-binding activity by exopolymers from adherent cells of a freshwater-sediment bacterium was demonstrated by a combination of equilibrium dialysis and flameless atomic absorption spectrometry. Crude, cell-free exopolymer preparations containing protein and polysaccharide components bound up to 37 nmol of Cu per mg (dry weight). A highly purified exopolysaccharide preparation bound up to 253 nmol of Cu per mg of carbohydrate. The conditional stability constant for the crude exopolymer-Cu complex was 7.3 X 10(8). This value was similar to those obtained for Cu complexes formed with humic acids and xanthan, an exopolysaccharide produced by Xanthomonas campestris. Studies conducted at copper concentrations, pHs, and temperatures found in sediments from which the bacterium was isolated indicated that the exopolymers were capable of binding copper under natural conditions.
Adhesiveness↗
Microbiology of a northern river: bacterial distribution and relationship to suspended sediment and organic carbon.
Epifluorescent microscopy showed as many as 4 x 10(6) bacteria/mL in the turbid waters of the Athabasca River near the tar sand deposits in northeastern Alberta. The numbers were usually similar upstream and downstream (60 km) from pilot-mining operations. The majority of bacteria existed as free-living cells in spite of the fact there were high concentrations of suspended sediment present (average 220 mg/L) during the ice-free period. Fluctuations in bacterial concentration were positively correlated (r = 0.86, P less than 0.05) with total organic carbon concentrations in the river water.
Alberta↗
Microscopic examination of natural sessile bacterial populations from an alpine stream.
Natural populations of bacteria assoiciated with the slime on submerged surfaces in a mountain stream were examined by phase-contrast and electron microscopy. The slime contained large numbers of bacteria which were predominantly gram-negative as determined by their cell wall structure. Examination of the in situ distribution of cells revealed that they were enmeshed in an extensive fibrous matrix whose component fibrils were stained with ruthenium red. The arrangement of slime fibrils immediately around individual bacterial cells suggested that this material was produced by these bacteria. This slime facilitated microcolony development and also anchored the bacteria to a particular surface. It is proposed that these slime-enmeshed microcolonies constitute functional communities within which most sessile bacteria live.
Bacteria↗
Some physiological effects of near-maximum growth temperatures on an obligately psychrophilic marine bacterium.
The heat inactivation of the obligately psychrophilic marine bacterium Ant-300 was investigated in terms of glucose uptake, the oxidation of glucose to CO2, and permeability control. At 13C, the maximum temperature for growth, and at slightly higher temperatures, CO2 evolution decreased with time during the oxidation of exogenously supplied glucose. The decrease in CO2 evolution appeared to be a result of heat-induced restrictions on glucose uptake. Leakage of intracellular metabolites apparently contributed to the cells decreased ability to take up glucose at elevated temperatures. A consequence of these heat-induced changes seemed to be the acceleration of cell starvation.
Carbon Dioxide↗