Lava Cave Microbial Communities Within Mats and Secondary Mineral Deposits: Implications for Life Detection on Other Planets

Abstract

Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai'i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai'i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai'i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies.

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

“…This indicates that the filaments are composed of carbon (likely organic matter) and not replaced by calcite. Noting that these pool fingers were active in the cave prior to sampling and treatment, we conclude that the filaments must be microbial filaments, confirming the interpretation of Melim et al (2008), Jones (2009Jones ( , 2010Jones ( , 2011, Northup et al (2011), and Miller et al (2012, 2014 that reticulated filaments are an unknown microbe. Ongoing research by our team is working to identify this microbe.…”

“…Jones (2009Jones ( , 2010Jones ( , 2011 reported on calcitized examples from cave pearls, terrestrial oncoids, and stalactites from the Cayman Islands. Northup et al (2011) identified reticulated filaments from a copper-silicate stalactite in a Hawaiian lava cave. Miller et al (2012) found Mnmineralized reticulated filaments in a granite water tunnel near Oporto, Portugal.…”

“…Although present in a large variety of settings, they are usually a small part of a larger community. Northup et al (2011) andMiller et al (2012) both did 16S rDNA clone libraries on samples containing reticulated filaments, but it is impossible to tell which results match up with the filaments. Miller et al (2012) also cultured samples, but did not successfully culture reticulated filaments.…”

Analytical pyrolysis and stable isotope analyses reveal past environmental changes in coralloid speleothems from Easter Island (Chile)

“…Speleothems in lava tubes generally consist of siliceous minerals owing to the mineralogy and chemical composition of the host basalts [30,31]. Nevertheless, calcium carbonate or calcium sulfate minerals (in the form of calcite or gypsum, respectively) have been reported on the walls and ceilings of lava tubes [32][33][34]. For instance, the internal structure of many cave corals, or coralloids, found in lava tube caves shows deposition layers with different mineralogical compositions, alternating between siliceous and carbonate minerals [27,35].…”

A Unique Prokaryotic Assemblage of Wall Biofilm of a Volcanic Cave (Daesubee) in Jeju

“…국외에서 는 동굴지역의 다양한 물리화학적 환경으로 인해 발생하는 독특 한 미생물 생태계에 대해서 보고되고 있다 (Chen et al, 2009;Tetu et al, 2013). 특히 미생물의 에너지원으로 작용하는 물질 들인 환원된 황 및 질소(H2S, NH3) 등이 존재하는 지역은 화학 무기영양(Chemolithotroph) 세균에 의해 생태계의 일차생산이 일어나는 독특한 미생물 생태계가 생성되기도 한다 (Northup et al, 2011;Borsodi et al, 2012;Tetu et al, 2013). filteration)을 통해 PCR 저해 물질을 제거하고 최종적으로 세균 및 고세균의 16S rRNA 유전자 증폭에 이용하였다.…”