# Comparison of Microbial Gene Diversity in Grassland Topsoil Depending on Soil Quality
## 3 Results
### Genomic Characteristics of Prokaryotes and Eukaryotes According to Soil Quality
#### 3.2.1 Characteristics of Prokaryotes
The predominant prokaryotes in the high-quality soil were _Nitrospira, Polycyclovorrans, Geobacter, Candidatus_ Nitrososphaera, Geothrix, Bacillus,_ and _Candidatus_ Nitrosopta inhabits a variety of environments, including soil, ground water, and fresh water, and can cause nitrification by oxidizing ammonia and nitrite [23]. _Polycyclovorrans_ inhabits phytoplankton and can utilize hydrocarbons as an energy source [24]. _Geobacter_ is an anaerobic bacterium with biological purification functions for oxidizing organic compounds and metals into carbon dioxide using electron acceptors [25]. _Candidatus_ Nitrososphaera is an ammonia-oxidizing archaea [26], and some species of the genus _Geothrix_ are functional bacteria for iron oxidation [27]. _Bacillus_, which is a facultative anaerobic, is thermally resistant, by virtue of the formation of endospores [28]. _Candidatus_ Nitrosolate belonging to the family Thaumarchaeota and _Nitrosopunilaceae_ have nitrogen-related functions [29]. Some predominant prokaryotes in the low-quality soil were Burkholderia-Caballeronia-Paraburkholderia, _Candidatus_ Udaeobacter, _Pseudomonas brassicacearum_ subsp. _Brassicacearum_, _Pseudarthrobacter_, _Steroidobacter_, _Crenobacter_, _Bradyrhizobium_, _Plantacinospora_, _Polaromonas_, _Rhizobacter_, _Rhodanobacter_, and _Bryobacter_. The genus _Burkholderia_ includes plant and animal pathogens, as well as species responsible for degrading organic pesticides and polychlorinated biphenyls [30; 31]. Members of the genus _Caballeronia_ contribute to nitrogen fixation and plant growth promotion, and members of the genus _Paraburkholderia_ inhabit tissues of plants such as pine trees, with no reported connection with human infection [32; 33]. _Candidatus_ Udaeobacter is a functional bacterium responsible for the secretion of antibiotics in the soil and the potential removal of trace gases [34]. Furthermore, _P. brassicacearum_ subsp. _brassicacearum_ is a plant pathogenic bacterium related to rapeseed (_Brassica napus_) roots and tomato [35]. Genus _Pseudarthrobacter_ was reclassified from the genus _Arthrobacter_, which is an aerobic bacterium that lives in soil. Genus _Steroidobacter_ includes species responsible for the degradation of hormones, including steroids and denitrification [36]. Members of the genus _Crenobacter_ have been isolated from environments such as thermal springs and caves [9], with members of the genus _Bradyrhizobium_ mainly found in the soil, including species responsible for nitrification and nitrogen fixation using leguminous bacteria. Members of the genus _Plantacinospora_ have been isolated from plant tissues; the genus _Polaromonas_ is psychrophilic and belongs to the family Comamonadaceae. In addition, members of the genus _Rhizobacter_ have been isolated from the soils of botanical gardens and have been reported to cause bacterial gall in carrots [37; 38]. Members of the genus _Rhodanobacter_ inhabit the soil; these include species responsible for the denitrification and degradation of pesticides, including indandae [39]. Members of the genus _Bryobacter_ have been isolated from peats containing accumulated and degenerated remains grasses and trees, and currently the genus contains _Bryobacter aggregatus_ as the only species [40]. Some bacteria analyzed in this study as potential markers included _Nitrospira_ related to the nitrogen cycle, including nitrification; archaea included _Candidatus_ Nitrososphaera and _Candidatus_ Nitrosotalea, Geobacter associated with biological purification; plant pathogenic bacteria such as _Burkholderia_, _Paraburkholderia_, _P. brassicacearum_, and _Rhizobacter_; _Candidatus_ Udaeobacter related to antibiotic secretion; and the genus _Steroidobacter_ and _Rhodanobacter_ related to material degradation. This result was similar to that of previous studies, including that by [PERSON] et al. [41], in that it comprises a group that could be used to indicate soil health and quality (based on NGS metadata).