The capabilities of bacteria and archaea to alter natural building stones – A review

Microorganisms, including bacteria, archaea, algae and fungi, colonize natural building stones. Bacteria are among the most relevant colonizers, as they impact substrates in multiple forms, primarily attributed to their high diversity. They alter rock properties, induce discoloration, dissolution or precipitation, which can lead to degradation over time or in some cases, protection. Numerous studies suggested a link between rock alteration and bacteria, although there are still inconclusive conclusions. Moreover, the role of archaea remains unresolved. Classical cultivation techniques capture a fraction of bacterial and archaeal diversity. Recently, culture-independent and omics-technologies provide tools to further understand their full diversity and true role. Based on field and experimental work, this comprehensive review provides an overview of biocolonization and potential changes during the 21st Century. To better understand the role of bacteria and archaea, the focus will be on their capabilities to alter natural building stones. It also includes a short overview of methods to understand the processes and dynamics of biocolonization. The conclusions of this work will not only improve our understanding of deterioration in general, but it can also make sustainable biorestoration with bacteria the preferred choice instead of chemical and physical agents.