# The Marine Bacterial Genus _Euzebya_ Is Distributed Worldwide in Terrestrial Environments: A Review
## 5 Relationship of _Euzebyales_ with Other Members of Microbial Communities in Diverse Environments  
A review of all the reports available in the literature provided some insights into the relationship of _Euzebya_ with other taxa in different environments. In fact, several taxonomic groups may inhabit the same niche as _Euzebya_. Thus, _Euzebya_ is present in most caves together with _Crossiella_, _Rubrobacter_, wb1-P19 (_Nitrosococcales_), and _Gaiella_, among other genera [23,27,28,29,33,34,35,36,37,38,39,35,34,33,36]. Caves are characterized by high relative humidity, in most cases near saturation, high mineral concentration, mainly of calcite in karstic and basaltic rocks in volcanic caves, as well as alkaline pH. In some pristine caves, oligotrophy is an environmental constraint.  
In saline and hypersaline environments, the order _Euzebyales_ is accompanied by other orders common to these extreme environments, such as _Nitriliruptorales_, _Rubrobacterales_, _Solirubrobacterales_, _Gaitalles_, _Acidimicrobiales_, _Oceanospirillales_, _Rhizobiales_, _KSA1 (_Bacteroides_), etc. [41,42,45,49,50,51,52,53,54,55,53]. Most members of these orders require high pH and salt concentrations, and oligotrophy is common in these environments. There are a few outstanding reviews on heavy metal resistance in halophilic _Bacteria_ and _Archaea_[120, 121, 122]. These and other studies [123,124] revealed that the mechanism of heavy metal resistance is associated with salinity tolerance and an increase in salinity and pH-enhanced tolerance to toxic metals. _Nitriliruptoria_ species possess salt tolerance mechanisms [56] and it is likely that heavy metal resistance could also be attributed to _Euzebya_.  
In deserts, _Euzebya_ has been found together with _Nitriliruptor_, _Rubrobacter_, _Gaiella_, _Halomonas_, etc. [62,64,65,68,70,71,64]. Water availability is scarce in deserts and environmental conditions become more challenging (e.g., strong oligotrophy and high  
\begin{table}
\begin{tabular}{l l l l} \hline
**Location** & **Taxa** & **Type of Sample** & **References** \\ \hline Bentonite deposit, Almeria, Spain & _Euzebya_ & Bentonite & [110] \\ \hline Coral reefs, Lakshadweep, India & _Euzebya_ & Demosponges & [111] \\ \hline Dogs, USA & _Euzebya_ & Feces & [112] \\ \hline Coastal waters, Yantai City, China, & _Euzebya_ & Bacteriplankton & [113] \\ \hline Dogs, USA & _Euzebya_ & Vomit & [114] \\ \hline Dogs, USA & _Euzebya_ & Oral cavity & [115] \\ \hline Human microbiome & _Euzebya_ & Urogenital & [116] \\ \hline Human microbiome & _Euzebya_ & Oral cavity & [117] \\ \hline Human microbiome & _Euzebya_ & Cerebrospinal fluid & [118] \\ \hline West coast of India & _Euzebya_ & Seawater & [119] \\ \hline \end{tabular}
\end{table}
Table 3: _Cont._mineral deposits). Most of these genera are known for their ability to resist extreme desiccation, high UV and ionizing radiation, temperature fluctuations, and high salinity and metal concentrations [62]. In addition, the pink color of most species of these genera is due to the presence of bacterioruberin, a carotenoid pigment with UV-protective properties. It is suggested that _Euzeyba_ may possess most of the above-described characteristics, although as far as we know no pigment identification has been reported for any of the three marine species.  
In soils, the co-occurrence of _Euzeyba_s with _Nitriliruptorales_, _Rubrobacterales_, _Soliruprobacterales_, _Gaiellales_, Oceanospirillales_, _Rhizobiales_, etc., is frequently reported [84; 86; 87; 88; 89], as previously stated for caves, saline, hypersaline, and desert environments.  
To summarize, some microbial lineages present in harsh terrestrial environments show successful adaptation strategies and the ability to cope with available scarce nutrient sources in unfavorable climatic and geochemical conditions.