DECAVE — Understanding the nature and origin of black deposits in caves: new insights on enigmatic microorganisms and secondary minerals valuable for astrobiology

Scientist in charge: Prof. Cesareo Saiz-Jimenez

Fellow: Dr. Ana Zélia Miller

Funding scheme: Marie Curie Actions – European commission’s 7th framework (FP7-MC-IEF)

Project reference: 328689

From 01-03-2014 to 29-02-2016



The advent of powerful new tools, the need to better understand the biodiversity, origins of life on Earth and on other planets, and the wide applications of the microbe-mineral interactions, have led to a rapid expansion of interest in subsurface environments. Recently reported results indicate signs of an early wet Mars and rather recent volcanic activity which suggest that Mars’s subsurface can house organic molecules or traces of microbial life, making the search for microbial life on Earth’s subsurface even more compelling. Caves on Earth are windows into the subsurface that harbor an especially interesting variety of mineral-utilizing microorganisms, which may contribute to the formation of unusual microstructures recognized as biosignatures. This proposal aims toward a multi- and inter-disciplinary approach to characterize the enigmatic microorganisms and unusual mineral features within black deposits found in limestone caves and lava tubes. A broad suite of tools from geology, mineralogy, geochemistry, hydrochemistry and molecular microbiology will be used: (i) To morphologically, geochemically and mineralogically characterize black deposits from Ardales Cave (Malaga, Spain) and lava tubes from Canary Islands; (ii) To identify and characterize the microbial communities within black deposits using powerful new molecular tools; (iii) To assess the microbe-mineral interactions associated with these cave deposits, permiting to elucidate on the role of microorganisms in the formation of secondary minerals and understand certain biomineralization and rock-weathering processes; (iv) To recognize biominerals, microbial fabrics or fossil bacteria as biosignatures valuable for astrobiology. Hence, the geomicrobiology of cave black deposits represents a research of great interest, which is likely to yield major advances on the identification of microbial biosignatures plausible to provide evidences on the origin of life on Earth and elsewhere in the Solar System.



  • Cennamo P, Caputo P, Marzano C, Miller AZ, Saiz-Jimenez C, Moretti A. 2014. Diversity of phototrophic components in biofilms from Piperno historical stoneworks. Plant Biosystems, doi:10.1080/11263504.2014.990538.
  • Coutinho ML, Miller AZ, Macedo MF. Biodiversity and biodeterioration of architectural ceramic materials: an overview. Journal of Cultural Heritage, doi:10.1016/j.culher.2015.01.006.

Book chapters:

  • Miller AZ, Dionísio A, Lopes ME, Afonso MJ, Chaminé HI, 2014. Microbe-mineral interactions in a Portuguese geo-archaeological site. In: C. Saiz-Jimenez (ed), The conservation of the subterranean cultural heritage, CRC Press – Taylor & Francis group, London. pp. 103-111. ISBN: 978-1-138-02694-0.
  • Garcia-Sanchez AM, Miller AZ, Jurado V, Dionísio A, Muralha VSF, Afonso MJ, Chaminé HI, 2014. Is the presence of bacterial communities related to the urban contamination sources of the 16th century Paranhos spring water galleries? In: C. Saiz-Jimenez (ed), The conservation of the subterranean cultural heritage, CRC Press – Taylor & Francis group, London. pp. 95-102. ISBN: 978-1-138-02694-0.
  • Sasso S, Miller AZ, Rogerio-Candelera MA, Laiz L, Scrano L, Bufo SA, Saiz-Jimenez C, 2014. Tertiary bioreceptivity of Hontoria limestone: assessment of secondary metabolites as natural biocides. In: M.A. Rogerio-Candelera (ed.), Science, Technology, and Cultural Heritage. London: CRC Press. pp. 185-190. ISBN: 978-1-138-02744-2.

Invited participation in conferences:

  • Miller AZ, 2014. “Secondary mineral deposits and associated microbe-mineral interactions in subsurface rock environments”. International conference: 22nd International Karstological School “Classical Karst”, June 16-20, 2014, Postojna, Slovenia.

Communications in international conferences:

  • Miller AZ, Hernández-Mariné M, Jurado V, Calaforra JM, Forti P, Toulkeridis T, Pereira MFC, Dionísio A, Saiz-Jimenez C, 2014. Biosignatures valuable for Astrobiology: the case of reticulated filaments. The 14th European Workshop on Astrobiology (EANA 2014), October 13-16, 2014, Edinburgh, Scotland.
  • Miller AZ, Suzuki S, Marques JM, Rocha C, Etiope G, Vance S, Christensen L. 2014. Morphological features of microorganisms dwelling in an active low-temperature serpentinization site, Cabeço de Vide, Portugal: a possible analogue to early Mars. The 14th European Workshop on Astrobiology (EANA 2014), October 13-16, 2014, Edinburgh, UK.
  • Miller AZ, Jurado V, Pereira MFC, Fernández O, Calaforra JM, Dionísio A, Saiz-Jimenez C. 2015. Cave speleothems as repositories of microbial biosignatures. European Geosciences Union General Assembly 2015 (EGU2015), 12 – 17 April 2015, Vienna, Austria.
  • Ferrier C, Ammari F, Bassel B, Bousquet L, Chapoulie R, Konik S, Lacanette D, Lefrais Y, Malaurent P, Miller AZ, Mauran G, Naessens F, Saiz-Jimenez C. Biomineralisation and coralloides: two calcitic facies involved in the conservation of paleolithic cave/rock art. XIX International rock art conference IFRAO 2015, 31 August – 4 September 2015, Caceres, Spain.
  • Fernández O, Gómez D, Naranjo M, Jurado V, Miller AZ, 2015. Nuevas galerías en la Cueva de Los Caños (Mazo, La Palma, islas Canarias): Notas sobre espeleometría, biocenosis y microbiología. 1st International Convention of Speleology, 1 – 3 May 2015, Barcelona, Spain.
  • Sasso S, Miller AZ, Rogerio-Candelera MA, Cubero B, Scrano L, Bufo SA, Saiz-Jimenez C. 2015. Non-destructive testing of stone biodeterioration and biocleaning effectiveness. International conference TECHNART 2015, April 27-30, 2015, Catania, Italy.