# Geomicrobiology: Latest Advances and Prospects
## 2 An Overview of Published Articles
Among the _Actinobacteriota_, the genera _Crossiella, Pseudonocardi, Rubrobacter_, and _Solirubrobacter_ stand out, and among the unclassified bacteria were recorded wb1-P19, _Euzebyaceae, Gemmataceae, Gemmatimonadaceae_, and PLTA13. The four genera of _Actinobacteriota_ found in New Mexico caves were also very abundant in lava caves from California [47]. The abundance of _Crossiella_ is noteworthy, not only in lava caves but also in karstic caves, where it reaches more than 50% of relative abundance in biofilms [48; 49]. A recent review also confirmed its abundance in soils and plant rhizosphere and the involvement of _Crossiella_ in biomineralization, and the synthesis of bioactive compounds is of interest for possible biotechnological applications [50]. In most caves, _Crossiella_ is associated with _Euzebya_ and/or uncultured members of the _Euzebyaceae_ family, uncultured _Gemmatinomadaceae_, wb1-P19, PLTA13, Ga0077536, _Nitrospira_, and _Vicinamibacteraceae_[23; 49], which were also retrieved by [PERSON] et al. [22] in his caves. [PERSON] et al. [23] reviewed the abundance and diversity of _Euzebyales/Euzebyaceae/Euzebya_ in terrestrial environments. The origin of this group of bacteria is marine, and no terrestrial _Euzebya_ has been isolated so far. This group of bacteria can thrive under harsh and quasi-extreme terrestrial conditions, including high concentrations of sodium and/or calcium, alkaline pH, highly variable temperatures, and water fluctuations. However, its role in the geochemical cycle of elements is unknown. The data collected indicate that _Euzebya_ is present throughout the biosphere. It is unclear whether these bacteria were dispersed from marine sources to terrestrial environments or if the sequences retrieved from caves and soils correspond to truly terrestrial species that have not yet been described. In his review, [PERSON] et al. [23] suggested the need to combine high-throughput sequencing with cultivation techniques that replicate environmental conditions to isolate terrestrial _Euzebya_ strains. Finally, the widespread geographical distribution of _Euzebya_ and the interest in understanding its biogeochemical role are expected to drive the optimization of culture media and the isolation of novel species from different terrestrial environments. The control of biodeterioration and the protection of cultural heritage is a research field of great interest. Microorganisms (including bacteria, fungi, and algae), as well as lichens, mosses, and plants, are major contributors to the deterioration of outdoor monuments. [PERSON] [51] compiled numerous reports on the involvement of microorganisms in the deterioration and preservation of materials such as stone, metals, graphic documents, textiles, paintings, and glass. In some cases, microorganisms can be used for biological cleaning of surfaces or for consolidation through biomineralization [52; 53; 54]. Lichens colonize rocks and all types of substrata (including stones, bricks, ceramics, metals, and glass). Lichens are particularly evident when covering the walls of many monuments [55; 56; 57]. Several authors have discussed the role of lichens in biodeterioration or bioprotection [58; 59; 60]. This issue presents a multifaceted challenge for conservators. [PERSON] et al. [24] delves into this topic through a multidisciplinary approach to investigate the interaction between lichens, microclimatic conditions, and the deterioration of stone in a Cappadocian church. This church is made of tuff with high porosity that deteriorates with freezing-thawing processes. The authors found that tuff surfaces without lichen cover show higher rates of deterioration compared with those colonized by lichens, whose coverage confers a protective effect due to a reduced water penetration. The protective effect was influenced by wall orientation, exposure to wind-driven rain events, and freezing-thawing cycles.