摘要:

Cream‐colored streamers ofThermothrix thioparawere found at the sulfide‐oxygen interfaces of active tufa mounds where reducing geothermal groundwaters mixed with the oxidizing atmosphere. In the Jemez hot springs, the molar ratio of sulfide to oxygen was 0.3 to 0.8 at streamer locations within the interface. This corresponded to the optimum stoichiometric proportion (0.5) necessary for sulfur metabolism. The mechanism of cell positioning at the interface was studied by shifting the interface location with a plastic cover to extend reducing conditions from the mouth of the spring to the edge of the plastic. Macroscopically visible streamers of filamentous cells became established at the new interface within a period of eight days. They could then be reestablished at the original interface by removing the cover.

ISSN:0149-0451    

DOI:10.1080/01490458409377797

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The mineral weathering capabilities ofThermothrix thioparawere investigated by scanning electron microscopy and energy dispersive X‐ray analysis.Thermothrix thioparais an extremely thermophilic, sulfur‐oxidizing bacterium that grows in a thermal spring whose principal minerals are calcium carbonate, pyrite, and sulfur. Crystals of these minerals were incubated in situ for periods up to eight days, removed, and examined. Results indicated thatT. thioparais partially responsible for weathering calcium carbonate by the production of sulfuric acid, thereby contributing to the formation of a porous tufa mound. Examination of ultravioletirradiated control crystals indicated that the sulfuric acid produced byT. thioparacaused solubilization of calcium carbonate even in the absence of direct bacterial colonization. Pyrite and sulfur were not visibly weathered, but instead were coated with calcium carbonate precipitate. During eight days incubation, growth forms ofT. thioparacolonizing the minerals progressed from unicells to filaments to nets of filaments. Bacteria other thanT. thioparaappeared after eight days, indicating an increased diversity.

ISSN:0149-0451    

DOI:10.1080/01490458409377798

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Growth and attachment rates ofThermothrix thioparaon calcite and pyrite were quantitated in a thiosulfate‐limited chemostat and in the thermal spring where the organism is found in nature. Surface growth rates were quantitated by using the surface colonization and exponential growth equations. These two models were compared as means of determining surface growth rates. In the chemostat,T. thioparacells colonizing calcite and pyrite surfaces grew at approximately one‐third the rate of suspended cells. However,T. thioparaattached to pyrite faster than to calcite. In the thermal spring, growth and attachment rates were equal on calcite and pyrite. It was concluded that the exponential growth equation overestimates in‐situ surface growth rates and thatT. thioparagrows more slowly when colonizing mineral surfaces than when growing in suspension. Lower growth rates on surfaces may be due to a reduced cell surface area for nutrient uptake or an increased specific maintenance rate.

ISSN:0149-0451    

DOI:10.1080/01490458409377799

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The biomass from which hydrocarbons were formed and the organisms responsible for its production are usually deduced by the use of biochemical markers. In the present study, using a simulated sedimentary system, cyanobacterial organic matter was buried in sediments and exposed to sequential environmental changes ranging from microaerobic conditions at ambient temperature to strongly reducing conditions at a biologically extreme temperature and pressure. Significant changes occurred in the composition of hydrocarbons and fatty acids isolated from the biomass that masked the characteristic patterns exhibited by the original cyanobacterial material. The changes depended on the particular environmental conditions to which the organic matter was exposed. The results stress the need for caution in interpreting biochemical markers in terms of their source material in sediments.

ISSN:0149-0451    

DOI:10.1080/01490458409377800

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The kinetics of manganese binding and oxidation by a marinePseudomonassp. have been determined under nutrient‐limited, steady‐state conditions. The first‐order rate constants for manganese binding by steady‐state cultures increased logarithmically with growth rate and were well within the range of values published for a variety of sedimentary and aquatic environments. In addition, the rate of manganese binding per cell appeared to be far faster than the growth kinetics.

ISSN:0149-0451    

DOI:10.1080/01490458409377801

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458409377802

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458409377803

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458409377804

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490458409377796

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor