scholarly journals The Role of Microbial Activity In the Generation of Lower Cretaceous Mixed FE-Oxide-phosphate Ooids from the Provencal Domain, French Maritime Alps

2013 ◽  
Vol 83 (2) ◽  
pp. 196-206 ◽  
Author(s):  
L. Barale ◽  
A. D'atri ◽  
L. Martire
Keyword(s):  
Microbial Activity ◽  
Lower Cretaceous ◽  
Maritime Alps ◽  
Fe Oxide

scholarly journals Rare microbes from diverse Earth biomes dominate community activity

2019 ◽  
Author(s):  
Rohan Sachdeva ◽  
Barbara J. Campbell ◽  
John F. Heidelberg
Keyword(s):  
Community Structure ◽  
Microbial Activity ◽  
Ecosystem Function ◽  
Total Activity ◽  
Reaction Rates ◽  
Community Activity ◽  
Crucial Component ◽  
Tightly Coupled ◽  
The Relationship

AbstractMicrobes are the Earth’s most numerous organisms and are instrumental in driving major global biological and chemical processes. Microbial activity is a crucial component of all ecosystems, as microbes have the potential to control any major biochemical process. In recent years, considerable strides have been made in describing the community structure,i.e. diversity and abundance, of microbes from the Earth’s major biomes. In virtually all environments studied, a few highly abundant taxa dominate the structure of microbial communities. Still, microbial diversity is high and is concentrated in the less abundant, or rare, fractions of the community,i.e. the “long tail” of the abundance distribution. The relationship between microbial community structure and activity, specifically the role of rare microbes, and its connection to ecosystem function, is not fully understood. We analyzed 12.3 million metagenomic and metatranscriptomic sequence assemblies and their genes from environmental, human, and engineered microbiomes, and show that microbial activity is dominated by rare microbes (96% of total activity) across all measured biomes. Further, rare microbial activity was comprised of traits that are fundamental to ecosystem and organismal health,e.g. biogeochemical cycling and infectious disease. The activity of rare microbes was also tightly coupled to temperature, revealing a link between basic biological processes,e.g. reaction rates, and community activity. Our study provides a broadly applicable and predictable paradigm that implicates rare microbes as the main microbial drivers of ecosystem function and organismal health.

scholarly journals Trace fossils, sedimentary facies and parasequence architecture from the Lower Cretaceous Mulichinco Formation of Argentina: The role of fair-weather waves in shoreface deposits

2018 ◽  
Vol 367 ◽  
pp. 146-163 ◽  
Author(s):  
Lindsey J.N. Wesolowski ◽  
Luis A. Buatois ◽  
M. Gabriela Mángano ◽  
Juan José Ponce ◽  
Noelia B. Carmona
Keyword(s):  
Lower Cretaceous ◽  
Sedimentary Facies ◽  
Trace Fossils ◽  
Fair Weather

scholarly journals Raymond Charles Casey. 10 October 1917—26 April 2016

2020 ◽  
Vol 68 ◽  
pp. 71-86 ◽  
Author(s):  
Peter F. Rawson ◽  
Adrian W. A. Rushton ◽  
Martin I. Simpson
Keyword(s):  
Great Britain ◽  
Soviet Union ◽  
Lower Cretaceous ◽  
Geological Survey ◽  
Time Service ◽  
Similar Role ◽  
Home Town ◽  
The Soviet Union ◽  
Spare Time

Raymond Casey was an internationally recognized expert in two entirely different fields—geology and philately. He achieved this despite leaving school at 14. By then he was already collecting and studying fossils from his home town, Folkestone, and in 1939, despite not having a degree, he obtained a post with the Geological Survey of Great Britain in the modest role of assistant to C. J. Stubblefield. After war-time service in the RAF, he returned to the Survey in a similar role, but spent much of his ‘spare time’ researching and publishing on Lower Cretaceous palaeontology and stratigraphy. His fortunes began to change when, at the age of 38, he was admitted to Reading University to study for a doctorate. His thesis on Lower Greensand stratigraphy and palaeontology was recognized as an outstanding study that led to major publications including a nine-part monograph of the ammonite faunas. Then, in the late 1950s, he also began to study faunas from Jurassic–Cretaceous boundary beds in eastern England as part of his official work and this led to him visiting the Soviet Union on several occasions from 1963 onward. On the first visit he met the academician Nalivkin in Leningrad, who, as well as being an eminent geologist, was a keen philatelist. This led to Raymond taking an enthusiastic interest in pre-revolutionary Russian postal history, which resulted in numerous publications and awards and, after his retirement, became his main focus of interest.

scholarly journals Specific Effect of Trace Metals on Marine Heterotrophic Microbial Activity and Diversity: Key Role of Iron and Zinc and Hydrocarbon-Degrading Bacteria

2018 ◽  
Vol 9 ◽  
Author(s):  
Federico Baltar ◽  
Andrés Gutiérrez-Rodríguez ◽  
Moana Meyer ◽  
Isadora Skudelny ◽  
Sylvia Sander ◽  
...  
Keyword(s):  
Trace Metals ◽  
Microbial Activity ◽  
Specific Effect ◽  
Degrading Bacteria ◽  
Iron And Zinc

scholarly journals The role of microorganisms in the formation of a stalactite in Botovskaya Cave, Siberia – paleoenvironmental implications

2013 ◽  
Vol 10 (9) ◽  
pp. 6115-6130 ◽  
Author(s):  
M. Pacton ◽  
S. F. M. Breitenbach ◽  
F. A. Lechleitner ◽  
A. Vaks ◽  
C. Rollion-Bard ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Manganese Oxides ◽  
Isotope Geochemistry ◽  
Isotopic Signature ◽  
Morphological Evidence ◽  
Calcite Deposition ◽  
Inorganic Precipitation ◽  
Co2 Degassing ◽  
Iron And Manganese

Abstract. Calcitic speleothems in caves can form through abiogenic or biogenic processes, or through a combination of both. Many issues conspire to make the assessment of biogenicity difficult, especially when focusing on old speleothem deposits. This study reports on a multiproxy analysis of a Siberian stalactite, combining high-resolution microscopy, isotope geochemistry and microbially enhanced mineral precipitation laboratory experiments. The contact between growth layers in a stalactite exhibits a biogenic isotopic signature; coupled with morphological evidence, this supports a microbial origin of calcite crystals. SIMS δ13C data suggest that microbially mediated speleothem formation occurred repeatedly at short intervals before abiotic precipitation took over. The studied stalactite also contains iron and manganese oxides that have been mediated by microbial activity through extracellular polymeric substance (EPS)-influenced organomineralization processes. The latter reflect paleoenvironmental changes that occurred more than 500 000 yr ago, possibly related to the presence of a peat bog above the cave at that time. Microbial activity can initiate calcite deposition in the aphotic zone of caves before inorganic precipitation of speleothem carbonates. This study highlights the importance of microbially induced fractionation that can result in large negative δ13C excursions. The microscale biogeochemical processes imply that microbial activity has only negligible effects on the bulk δ13C signature in speleothems, which is more strongly affected by CO2 degassing and the host rock signature.

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