Update: Living Reticulated Filaments from Herbstlabyrinth-Adventhöhle Cave System, Germany

Melim, Leslie A.; Northup, Diana E.; Spilde, M.; Boston, Penelope J.

doi:10.4311/2015mb0112

Cited by 12 publications

(12 citation statements)

References 6 publications

(15 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The study of the samples by field emission scanning electron microscopy (FESEM) revealed the presence of filamentous microorganisms in the vermiculations of Morgana Cave (Figure 3). Most of the microbial features observed in samples M1, M3, M4, M5, and M6 resemble the enigmatic reticulated filaments reported in caves worldwide (Melim et al, 2008;Miller et al, 2012), which are long tubular filaments with peculiar surface ornamentation (Miller et al, 2012;Melim et al, 2015).…”

Section: Field Emission Scanning Electron Microscopymentioning

confidence: 59%

See 1 more Smart Citation

Microbial Communities in Vermiculation Deposits from an Alpine Cave

et al. 2020

View full text Add to dashboard Cite

Morgana Cave is located in Val di Scerscen, Central Italian Alps. The cave opens at an altitude of 2,600 m a.s.l. close to the retreating glacier Vedretto di Scerscen, and its entrance was discovered 30 years ago hidden underneath the glacier. A characteristic of this cave is the occurrence of vermiculation deposits on the walls and ceiling. In general, the composition of the microbial communities in cave vermiculations is relatively unknown and rarely investigated. Here we present the data of a geomicrobiological study of vermiculations from an Alpine cave subjected to extreme climate conditions. The microbial communities were dominated by 13 main phyla of Bacteria, and contained a negligible percentage (<1%) of Archaea. The two major bacterial classes were Gammaproteobacteria and Betaproteobacteria, whose metabolic traits were mainly associated with the nitrogen cycle. In addition, psychrophilic and methanotrophic bacterial groups were identified. The occurrence of a large number of uncultured members, at the lowest taxonomic ranks, indicated the presence of still unexplored microbial taxa in the vermiculations.

show abstract

Section: Field Emission Scanning Electron Microscopymentioning

confidence: 59%

“…These filaments were composed of an inner cellular structure coated by an exterior sheath of manganese oxides (Miller et al, 2012). Melim et al (2015) reported living reticulated filaments associated with clay minerals in a limestone cave in Germany. They were rich in carbon, without mineralized sheaths.…”

Section: Discussionmentioning

confidence: 99%

Microbial Communities in Vermiculation Deposits from an Alpine Cave

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Those particular filamentous forms, with the size of about 0.5 μm width and up to 75 μm length, are often found in subsurface environment, including limestone or lava caves, and possess higher carbon content than the one typically observed for calcite minerals, suggesting their biogenic origin. However, the associated microorganisms are not yet identified (Melim et al, 2008 , 2015 ; Northup et al, 2011 ; Miller et al, 2012 ). Overall, these observations tend to confirm the hypothesis of filamentous microorganisms (bacteria and fungi) serving as a nucleation sites for moonmilk mineral deposition (Canaveras et al, 2006 ).…”

Section: Resultsmentioning

confidence: 99%

Assessment of the Potential Role of Streptomyces in Cave Moonmilk Formation

et al. 2017

View full text Add to dashboard Cite

Moonmilk is a karstic speleothem mainly composed of fine calcium carbonate crystals (CaCO3) with different textures ranging from pasty to hard, in which the contribution of biotic rock-building processes is presumed to involve indigenous microorganisms. The real microbial input in the genesis of moonmilk is difficult to assess leading to controversial hypotheses explaining the origins and the mechanisms (biotic vs. abiotic) involved. In this work, we undertook a comprehensive approach in order to assess the potential role of filamentous bacteria, particularly a collection of moonmilk-originating Streptomyces, in the genesis of this speleothem. Scanning electron microscopy (SEM) confirmed that indigenous filamentous bacteria could indeed participate in moonmilk development by serving as nucleation sites for CaCO3 deposition. The metabolic activities involved in CaCO3 transformation were furthermore assessed in vitro among the collection of moonmilk Streptomyces, which revealed that peptides/amino acids ammonification, and to a lesser extend ureolysis, could be privileged metabolic pathways participating in carbonate precipitation by increasing the pH of the bacterial environment. Additionally, in silico search for the genes involved in biomineralization processes including ureolysis, dissimilatory nitrate reduction to ammonia, active calcium ion transport, and reversible hydration of CO2 allowed to identify genetic predispositions for carbonate precipitation in Streptomyces. Finally, their biomineralization abilities were confirmed by environmental SEM, which allowed to visualize the formation of abundant mineral deposits under laboratory conditions. Overall, our study provides novel evidences that filamentous Actinobacteria could be key protagonists in the genesis of moonmilk through a wide spectrum of biomineralization processes.

show abstract

“…In many caves, stromatolite-like laminated structures are very common and formed microbially but not in response to light direction as they are not photosynthetic but heterotrophic or chemolithotrophic (Melim et al , 2009). They usually are pendant structures that grow in pools and fossilize very well, but living examples are known (Melim et al , 2015).…”

Section: Biosignature Phenomenamentioning

confidence: 99%

Deciphering Biosignatures in Planetary Contexts

et al. 2019

Self Cite

View full text Add to dashboard Cite

Microbial life permeates Earth's critical zone and has likely inhabited nearly all our planet's surface and near subsurface since before the beginning of the sedimentary rock record. Given the vast time that Earth has been teeming with life, do astrobiologists truly understand what geological features untouched by biological processes would look like? In the search for extraterrestrial life in the Universe, it is critical to determine what constitutes a biosignature across multiple scales, and how this compares with “abiosignatures” formed by nonliving processes. Developing standards for abiotic and biotic characteristics would provide quantitative metrics for comparison across different data types and observational time frames. The evidence for life detection falls into three categories of biosignatures: (1) substances, such as elemental abundances, isotopes, molecules, allotropes, enantiomers, minerals, and their associated properties; (2) objects that are physical features such as mats, fossils including trace-fossils and microbialites (stromatolites), and concretions; and (3) patterns, such as physical three-dimensional or conceptual n -dimensional relationships of physical or chemical phenomena, including patterns of intermolecular abundances of organic homologues, and patterns of stable isotopic abundances between and within compounds. Five key challenges that warrant future exploration by the astrobiology community include the following: (1) examining phenomena at the “right” spatial scales because biosignatures may elude us if not examined with the appropriate instrumentation or modeling approach at that specific scale; (2) identifying the precise context across multiple spatial and temporal scales to understand how tangible biosignatures may or may not be preserved; (3) increasing capability to mine big data sets to reveal relationships, for example, how Earth's mineral diversity may have evolved in conjunction with life; (4) leveraging cyberinfrastructure for data management of biosignature types, characteristics, and classifications; and (5) using three-dimensional to n -D representations of biotic and abiotic models overlain on multiple overlapping spatial and temporal relationships to provide new insights.

show abstract

Update: Living Reticulated Filaments from Herbstlabyrinth-Adventhöhle Cave System, Germany

Cited by 12 publications

References 6 publications

Microbial Communities in Vermiculation Deposits from an Alpine Cave

Microbial Communities in Vermiculation Deposits from an Alpine Cave

Assessment of the Potential Role of Streptomyces in Cave Moonmilk Formation

Deciphering Biosignatures in Planetary Contexts

Contact Info

Product

Resources

About