Role of Fungi in the Biomineralization of Calcite

Abstract

Abstract:In the field of microbial biomineralization, much of the scientific attention is focused on processes carried out by prokaryotes, in particular bacteria, even though fungi are also known to be involved in biogeochemical cycles in numerous ways. They are traditionally recognized as key players in organic matter recycling, as nutrient suppliers via mineral weathering, as well as large producers of organic acids such as oxalic acid for instance, an activity leading to the genesis of various metal complexes such as metal-oxalate. Their implications in the transformation of various mineral and metallic compounds has been widely acknowledged during the last decade, however, currently, their contribution to the genesis of a common biomineral, calcite, needs to be more thoroughly documented. Calcite is observed in many ecosystems and plays an essential role in the biogeochemical cycles of both carbon (C) and calcium (Ca). It may be physicochemical or biogenic in origin and numerous organisms have been recognized to control or induce its biomineralization. While fungi have often been suspected of being involved in this process in terrestrial environments, only scarce information supports this hypothesis in natural settings. As a result, calcite biomineralization by microbes is still largely attributed to bacteria at present. However, in some terrestrial environments there are particular calcitic habits that have been described as being fungal in origin. In addition to this, several studies dealing with axenic cultures of fungi have demonstrated the ability of fungi to produce calcite. Examples of fungal biomineralization range from induced to organomineralization processes. More examples of calcite biomineralization related to direct fungal activity, or at least to their presence, have been described within the last decade. However, the peculiar mechanisms leading to calcite biomineralization by fungi remain incompletely understood and more research is necessary, posing new exciting questions linked to microbial biomineralization processes.

Calcium-mediated stabilisation of soil organic carbon

“…This physical constrainment can occur over large spatial scales in biologically limiting environments, like those present in Histosols or Cryosols, where waterlogged or frozen conditions severely limit the oxidative degradation of organic substrates (Dörfer et al 2013), but can also occur at smaller spatial scales. Mechanisms for small scale physical separation include hydrophobic interactions arranging substrates into a micellar structure (Chassin 1979), SOC inclusion within a mineral or cogenetic mineral assemblage (Bindschedler et al 2016), SOC intercalation within phyllosilicates (Theng et al 1986), and occlusion of SOC within pedogenic aggregates (Adu and Oades 1978). Thus, the physical constrainment of aerobic decomposition can occur over plurimetric to micrometric scales and stabilises SOC in nearly all soil environments.…”

“…Biomineralisation of CaCO 3 can either be induced within cells, mediated by biological activity that stimulates physicochemical precipitation, or initiated by the presence of an existing biological matrix that initiates crystal nucleation and growth in the extracellular environment (Bindschedler et al 2016). During each of these forms of biomineralisation, SOC can become included and encapsulated within the crystal structure (Verrecchia et al 1995).…”

Substrate and spatial variables are major determinants of fungal community in karst caves in Southwest China

“…Previous studies suggest that caves support a considerable diversity of microbes (Bindschedler, Cailleau, & Verrecchia, 2016;Carmichael et al, 2015;Dhami, Quirin, & Mukherjee, 2017;Hathaway et al, 2014;Jiang et al, 2017;Ortiz et al, 2013;Vanderwolf, Malloch, McAlpine, & Forbes, 2013;Zhang et al, 2017). Ortiz et al (2013) investigated the bacterial diversity in Kartchner Caverns using 454pyrosequencing, and 1,994 OTUs were obtained from ten sample sites.…”

Evidence of a Role for Aerobic Bacteria in High Magnesium Carbonate Formation in the Evaporitic Environment of Dohat Faishakh Sabkha in Qatar

“…Biominerals are of great importance due to their huge impact on the global biogeochemical cycle (Bindschedler et al, 2016). The most abundant biogenic minerals are the calcium carbonates (Mukherjee, 2011).…”