Molecular Approaches to Studying Living Stromatolites
The presence of stromatolites dates back to some 3.5–3.8 billion years in earth’s history, a time period that witnessed the appearance of the first forms of life (Schopf 2006). The microbial communities that constituted these complex structures played a s
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1 Introduction The presence of stromatolites dates back to some 3.5–3.8 billion years in earth’s history, a time period that witnessed the appearance of the first forms of life (Schopf 2006). The microbial communities that constituted these complex structures played a significant role in the global biogeochemical cycles and sedimentation (Dupraz and Visscher 2005). The impetus behind stromatolite genesis is not clearly known and the modes of accretion, and lithification have long been debated; both biotic and abiotic mechanisms have been suggested for stromatolite formation (Grotzinger and Knoll 1999; Grotzinger and Rothman 1996). Irrespective of their origin, the contributions of stromatolites to the primeval environmental conditions are undisputed. Owing to their importance, stromatolites have formed the core of a growing area of microbial ecology and evolution-based research. Modern stromatolites, the living counterparts of fossilized stromatolites, offer a glimpse as to how microbial communities may have prevailed on the early Earth, and allow unprecedented access to the functional complexity of these systems. Microbial mats that are also considered as living analogues of ancient stromatolites have been studied to interpret ancient stromatolites and have been particularly resourceful in comprehending the formation of extant stromatolites. Layering of lithified microbial mats is in fact attributed to stromatolite
B.P. Burns (*), N. Baburajendran, and J. Dharmawan School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW 2052, Australia e-mail: [email protected]
J. Reitner et al., Advances in Stromatolite Geobiology, Lecture Notes in Earth Sciences 131, DOI 10.1007/978-3-642-10415-2_5, # Springer-Verlag Berlin Heidelberg 2011
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Fig. 1 Living stromatolites of Shark Bay, Western Australia
development (Dupraz and Visscher 2005). Over the years great progress has been made in unraveling the mysteries of these organosedimentary structures with much focus on the microbial diversity and the process of lithification. The most extensively studied groups of modern stromatolites belong to the open marine waters of Exuma Sound, Bahamas, and the Hamelin Pool at Shark Bay, Western Australia (Fig. 1). The studies on these groups of stromatolites have uncovered significant data that constitute our present understanding of stromatolite formation and ecology. The initial techniques used for the study of stromatolites have ranged from microscopy to traditional culturing. Progressively RNA and DNA based methods are being utilized. Not more than 1% of microorganisms found in many different environments can be cultured and hence, characterized (Handelsman 2004). Most of the microbial communities such as those associated with stromatolites are highly complex and contain large numbers of microbes; studying such communities by means of traditional methods is not feasible.
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