摘要:

Jarosite [KFe3(SO4)2(OH)6] was precipitated in cultures ofThio‐bacillus ferrooxidansgrowing on ferrous sulfate. This basic ferric sulfate was characterized by x‐ray diffraction patterns and infrared spectra and was very similar to jarosite produced chemically from acidic ferric sulfate.

ISSN:0149-0451    

DOI:10.1080/01490457909377731

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

An example of a recent tubiform fossilGirvanellais reported from a transitory, freshwater flash‐spring, in an area of the Borrego Desert, near San Diego, California. It occurs as the preserved, calcite‐impregnated sheath of the blue‐green algaPlectonema gloeophilumBorzi. In size and form, the fossil is identical to the first specific description of a recentGirvanella.The data presented give strong support to the idea of specificity for calcification in some blue‐green algae.

ISSN:0149-0451    

DOI:10.1080/01490457909377732

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Six lakes of the Wadi Natrun, Egypt, were studied with respect to the chemical composition of their brines and the occurrence of microbial mass developments. All investigated lakes showed pH values of approximately 11 and a total salt content of generally more than 30%. The main components were sulfate, carbonate, chloride, sodium, and minor amounts of potassium. Only traces of magnesium and calcium were present, but unusually high concentrations of organic carbon compounds, nitrogen compounds, and phosphate were found. Mass developments of phototrophic sulfur bacteria, halobacteria, cyanobacteria, and green algae were observed. The functions of complete nitrogen and sulfur cycles in the alkaline brines are discussed. The properties of the lakes and their ecology are compared with data on the Dead Sea and Great Salt Lake, Utah.

ISSN:0149-0451    

DOI:10.1080/01490457909377733

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Nonionic surfactants increase the rate of selective hydrocarbon utilization byAcinetobacterSL1. Within an homologus series of nonionic surfactants, growth on and utilization of a model oil byAcinetobacterSL1 is dependent upon the surfactant hydrophile‐lipophile balance (HLB). Biological effectiveness of the surfactants apparently is related to the degree of micelle formation by the surfactant in the aqueous phase. A simple algebraic expression describing the response ofAcinetobacterSL1 to surfactant concentration gives a measure of the biological effectiveness of an individual surfactant. A cationic and an anionic surfactant inhibited the growth ofAcinetobacterSL1 andPseudomonasSL6 on hydrocarbon substrates. These results are discussed in relation to the selection of suitable detergents for increasing the effective biodegradation of pollutant oil in aquatic habitats.

ISSN:0149-0451    

DOI:10.1080/01490457909377734

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Microbiological transformations of sulfur compounds discriminate to various degrees between the stable sulfur isotopes32S and34S. Comparatively little is known on isotopic effects associated with sulfur‐oxidizing organisms, and the interpretation of results is complicated since the sulfur pathways are poorly defined and compounds containing two or more sulfur atoms at different oxidation states may be involved. Dissimilatory reduction of sulfate, and sulfite reduction by certain assimilatory microorganisms, causes particularly marked isotopic effects, the expression of which depends on the extent of reaction and other incompletely defined environmental conditions. Models have been proposed to account for these effects based on current knowledge of the reduction pathways. Many of the trends observed during dissimilatory sulfate reduction in the laboratory can also be found in the modern environment leaving little doubt that microbiological factors play a significant role in determining sulfur isotope distributions in nature. However, unusually large isotopic effects, rarely approached in the laboratory, are often observed in nature. The reasons for this are not entirely clear, but in sediments it is possible that diffusional isotopic effects are imposed on biological effects.

ISSN:0149-0451    

DOI:10.1080/01490457909377735

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

New types of microbial fossils and new occurrences of fossils previously reported only from the Beck Spring Dolomite of the Pahrump Group are now recognized from each of the three formations of the Pahrump Group (Crystal Spring Formation, Beck Spring Dolomite, and Kingston Peak Formation) approximately 1.3 X 10° years old. Comprising perhaps eight or nine distinctive forms, these fossils are characteristically preserved as faint ghostlike structures whose low‐contrast outlines are clearly revealed only when illuminated by a xenon lamp and recorded on high‐contrast film. They represent a distinctive, previously overlooked or neglected type of preservation that has significantly extended the known distribution of microbial fossils in the Pahrump. They include the oldest occurrence known to us of filaments designatable asGirvanellaand apparently the first from rocks of pre‐Phanerozoic age. Similar fossils were also found, using the same techniques, in the Chuar Group of the Grand Canyon and in the Uluntui Suite of middle Riphean age in eastern Siberia. Although time correlation of pre‐Phanerozoic rocks based on similar microbial assemblages would be premature, similarity between such assemblages in all formations of the Pahrump Group and with that of the Uluntui Suite is consistent with the inferred unity and middle Riphean age of the Pahrump Group. In addition to theGirvanellawe find two smaller types of filaments, two kinds of simple spheroids, and three composite forms (two spheroids and one stalked cluster) that attain diameters up to 80 μm and are probably eucaryotic.

ISSN:0149-0451    

DOI:10.1080/01490457909377736

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490457909377730

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor