Showing papers by "Thomas D. Brock published in 1974"

Nutritional studies on Chloroflexus, a filamentous photosynthetic, gliding bacterium

Abstract: Nutritional studies on four different strains of Chloroflexus, a new genus of filamentous, photosynthetic bacteria are described This organism appears to be related to several different procaryotic groups, and in particular to the green sulfur bacteria and blue-green algae Unlike these autotrophs, however, Chloroflexus is nutritionally diverse, being able to grow aerobically as a light-independent heterotroph, and anaerobically as a photoautotroph or photoheterotroph Numerous organic carbon sources including hexoses, amino acids, short chain fatty acids, organic acids, and some alcohols are utilized under various growth conditions These results suggest that this organism may be among the most nutritionally versatile organisms known

Bacterial stromatolites: origin of laminations.

Abstract: Laminated mats composed of motile filamentous photosynthetic bacteria and nonmotile unicellular blue-green algae occur in a large number of Yellowstone hot springs at temperatures between 55° and 70°C. Field studies indicate that the bacteria are the predominant mat-forming component. Under low light intensities, mats composed exclusively of bacteria can be formed. The bacteria undergo a diurnal migration, moving on top of the algae dnring the night and becolming mixed again with the algae during the day of differential migration of the bacteria in daily response to reduced light intensities. This response to light is exactly opposite to that previously reported for filamentous stromatolite-forming, blue-green algae, but the net result is the same—formation of a laminated mat.

Algal excretion and bacterial assimilation in hot spring algal mats1

Abstract: SUMMARY Benthic algal-bacterial mats are present in the effluents of alkaline hot springs at temperatures between 50 and 73 C. The thin surface layer is composed of the unicellular blue-green alga Synechococcus lividus. Also present in the surface layer and forming thick, orange mats beneath it, are filamentous, phototrophic, gliding bacteria of the genus Chloroflexis, also capable of heterotrophic growth. The very low species diversity and the constancy of the hot spring environment, make these mats a good ecosystem for studying the transfer of nutrients from the algae to the bacteria. To determine whether the alga might supply organic materials to the bacterium, excretion by natural populations of S. lividus was studied in the field by means of short-term radioisotope experiments. Under optimal conditions for photosynthesis, between 3 and 12% of the total 14C fixed was excreted as 14C-labeled organic compounds. Variations in cell density at concentrations of S. lividus approximating those found in the mat had no effect on the percentage excretion. However, at cell densities below a threshold, level, the percentage excretion increased with diminishing cell density. Except at very low light intensities the percentage of fixed carbon excreted, was very similar for all light intensities tested. Excretion at temperatures approaching the upper limit for growth was not significantly different from the percentage excretion values observed at lower temperatures. 14C-labeled organic compounds excreted during algal photosynthesis could be subsequently assimilated by natural populations of the bacteria present in the mat.

Ecology of Iron-Oxidizing Bacteria in Pyritic Materials Associated with Coal

Abstract: A technique was developed for measuring 14CO2 uptake by chemolithotrophic bacteria directly in pyritic materials associated with coal and coal refuse. There was good correlation between 14CO2 uptake, as determined by this technique, and the most probable number of iron-oxidizing bacteria. Maximal 14CO2 uptake occurred in coal refuse material 2 to 3 years old, and only slight incorporation was demonstrated in fresh material or material 40 years old. Samples taken from the surface of the coal refuse pile always demonstrated maximal 14CO2 uptake, and in most samples, only slight activity was demonstrated at depths below 8 to 10 cm. Optimal uptake of 14CO2 by natural samples occurred at 20 to 30 C and at a moisture content of between 23 and 35%. In addition to chemolithotrophic bacteria, heterotrophic fungi and yeasts were also routinely isolated in high numbers from acidic coal refuse. In contrast, acidophilic, heterotrophic bacteria were either absent or present in low numbers in such acidic samples.

Immunofluorescence Approach to the Study of the Ecology of Thermoplasma acidophilum In Coal Refuse Material

Abstract: Specific immunofluorescence staining was applied to the study of the localization, distribution, and growth of Thermoplasma acidophilum in its natural habitat, the coal refuse pile. Different antigenic groups of T. acidophilum could be isolated from the same refuse pile, and the same antigenic groups were isolated from piles from different geographical areas. No correlation could be established between the antigenic groups and the pH or temperature of the habitats. Brightly fluorescing cells of T. acidophilum were detected on microscope slides buried in contact with the coal refuse material or immersed in the water in the stream draining a refuse pile. T. acidophilum grew when inoculated into either coal refuse material and/or an aqueous extract of coal refuse when incubated at its optimal temperature of 55 C, but not when incubated at room temperature or 37 C. The coal refuse pile appears to be a primary habitat for T. acidophilum.

Population ecology of Sulfolobus acidocaldarius

Abstract: Ecology of Sulfolobus acidocaldarius was studied in situ by the use of the immunofluorescence and immunodiffusion techniques. The fluorescent antibodies (FA) prepared against four strains of Sulfolobus were highly reactive against their homologous antigens. Two of the FA's were strain specific and the other two exhibited reciprocal corssreactions against each other's antigens, but immunodiffusion patterns showed that the two strains were not identical. The growth of a serologically distinct isolate in a hot spring was measured by immunofluorescence staining of immersion slides. On glass immersion slides Sulfolobus grew and formed colonies with a mean-doubling time of approximately 36 h. Immunofluorescence was applied to study the geographical distribution of two serologically different strains and to establish population composition of individual springs. One strain was found in all sites studied, and most springs contained more than one serologic type. Immunodiffusion was capable of detecting specific Sulfolobus antigens in hot springs which contained a high population of FA-reactive cells.

Population ecology of Sulfolobus acidocaldarius. I. Temperature strains.

Abstract: Optimal temperatures for elemental sulfur oxidation were determined for Sul/olobus acidocaldarius populations in a variety of hot, acid springs in Yellow- stone National Park, Wyoming. Cultures were obtained from some of the springs by enrichment and isolation at different incubation temperatures, and the optimal temperatures for these were also determined. The optimum temperature for sulfur oxidation was the same as that for 14C0~ incorporation and for the rate of growth of several isolates. For populations in springs of 57--80~ the optimal temperatures were either equal to or higher than the habitat temperature. However, the optima for bacteria in the high-temperature springs (90--92~ were considerably lower than the observed habitat temperature, suggesting an inability to adapt to tempera- tures near boiling. These results, as well as the properties of the bacteria isolated from the sites, suggest that a limited number of temperature strains of Sul/olobus exist in nature. A mixture of strains occurred at severaI of the sites, pointing to an unexpected heterogeneity in these well-mixed springs.

Growth Rates of Sulfolobus acidocaldarius in Nature

Abstract: Turnover times for water passing through several Sulfolobus acidocaldarius-containing springs were determined by measuring the dilution rates of small amounts of sodium chloride that were added to the springs. Chloride was diluted out exponentially, while concentrations of the bacteria remained constant. Additionally, temperature, pH, and chemical composition of the springs also remained constant during the time that the chloride was being diluted. The springs are thus steady-state systems, and since the rates of bacterial growth must be at least equal to the chloride dilution rates, minimal doubling times for the bacterial populations can be calculated. Half-times for chloride dilution, equivalent to bacterial doubling times, were on the order of 10 to 20 h for springs ranging in volume from about 20 to 2,000 liters, but approximately 30 days for two larger springs of about 1 million liters. Formaldehyde-fixed cells of a serologically distinguishable strain of S. acidocaldarius were also added as markers to four of the smaller springs, and the dilution rates of these bacteria were compared with the chloride dilution rates. The rates agreed reasonably well, thus verifying the growth rates obtained from the chloride dilution rates. In three springs, exponential growth was studied by draining the springs and allowing them to refill with bacteria-free water. Exponential doubling times were on the order of a few hours, much more rapid than steady-state doubling times. The methods used in this work may have wider utility in aquatic environments.

A seasonal diatom in a frozen wisconsin lake1

Abstract: SUMMARY An extensive bloom of a stalked diatom, Cymbella sp., developed under the ice in Lake Wingra, a hard-water lake in southern Wisconsin. The diatoms were attached to decomposing plants of Myriophyllum spicatum L. Uptake of H14CO3− showed the Cymbella to have an optimum temperature for carbon fixation of 25 C throughout the winter. Microscopic examination of samples taken from January through April showed Cymbella to dominate all other eucaryotic organisms. It is concluded that despite the fact this organism predominates in this winter habitat, it does not become optimally adapted to the temperature of its environment.

Immunodiffusion Analysis of Membranes of Thermoplasma acidophilum

Abstract: Isolates of Thermoplasma acidophilum were divided into serological groups based on immunodiffusion studies of solubilized-membrane preparations.