*2.2.2 Archaea role in soil processes*

Ren et al., [50] through studies performed on agricultural soils in that different management strategies and practices were applied demonstrate that archaea are serious contributors to soil processes such as nutrient cycling, ammonia oxidation, and minerals weathering. Archaea are involved also in carrying out N2 fixation as well reduction of atmospheric *N*<sup>2</sup> to *NH*<sup>þ</sup> 4 .


**Table 2.**

*Main autotroph and heterotroph bacteria roles in soil (adapted after Pepper and Gentry, [19]).*

*Global Change Drivers Impact on Soil Microbiota: Challenges for Maintaining Soil… DOI: http://dx.doi.org/10.5772/intechopen.111585*

#### *2.2.3 Fungi role in soil processes*

Fungi perform several key functions in soil. They are considered important decomposers and mutualists. Saprophytic fungi, the main decomposers, degrade dead organic materials. These are transformed into fungal biomass, CO2, and several small but essential molecules (e.g., amino acids). Hussain et al., [51] and Chaudhary et al., [52] reported that *Phoma sp*. and *Penicillium sp*., respectively, induce synthetic resistance against plant pathogens. Fungi such as *Trichoderma sp.* and *Phoma sp*. enhance biomass production, improve plant growth [53], and promote lateral root growth [54]. Mutualists are mycorrhizal fungi. Most time, these colonize plant roots. They favor phosphorous solubility and bring micro and macronutrients to plants. Arbuscular mycorrhiza fungi were reported that increase soil nutrient availability and improve nutrient acquisition by plants. Heidari and Karami [55] reported that mycorrhizas could enhance crop yield by fostering host resource uptake through sharing. They could minimize nutrient loss under extreme meteorological events also. Celik et al., [56] through their study assessed that arbuscular mycorrhiza fungi are important in both of forming stable soil aggregates as well in the improvement of water retention. Also, there are many studies that report their efficiency in the phytoremediation of polluted soils [50]. Yeast was summarized by Pepper and Gentry, [19] as consumers of bacteria and plant root exudates for the synthesis of plant protectants and many other useful and important compounds that enhance plant growth. Beeck et al., [27] highlighted that yeast produces significant extracellular polymeric substances. For that, yeast is often associated with soil structure formation and maintenance.

#### *2.2.4 Algae role in soils*

Recently, many studies have evidenced that algae are important in maintaining soil fertility. In their life cycle, they contribute to soil particle binding and facilitate soil erosion prevention [36]. It was reported also that algae are involved in rock weathering, thus they could be considered as wrapped up in soil structure building [57]. Algae increase soil water retention capacity, enhance submerged aeration through photosynthesis processes, and contribute in the reduction of soil nitrates through leaching or drainage processes [19]. After their life cycle, they contribute to soil nutrient resources with large amount of organic carbon.

#### *2.2.5 Protozoa role in soil*

Protozoa maintain microbial diversity and functional stability (microbial/bacterial equilibrium) through their nutrition (feeding and ingestion) and multitrophic interactions at that take place. Chen et al., [58] highlight in their paper protozoa positive influences on nutrient availability for plants, release of hormones for plant development, and biological control agents against organisms that could induce potential harmful diseases in plants. Ronn et al., [59] acknowledged that protozoa are also involved in the accumulation and stabilization of organic carbon in the soil.

## **3. Soil ecosystem services: Connection with soil microbiota**

According to the implications that components of soil microbiota have in various soil functions, becomes obvious that soil belowground microbiota diversity is an

important resource for maintaining the functioning of soil ecosystem and consequently of ecosystem services on which society depends. Soil microbiota through their metabolic pathways is directly involved in greenhouse gas removal, nutrient cycling, pathogens inactivation, and pollutants degradation. **Table 3** gives a summary of the





#### **Table 3.**

*Soil microbiota involvement in soil functions and processes assures diverse support, provision, and regulation services provision by the soil ecosystem (adapted after Aislabie and Deslippe, [60]).*

transformation in an available form for the plant, as well as through soilroot exchange enhancement, thus alleviating soil surface enhancement. Microbiota produces biological glues, and facilitates physical entanglement by roots and fungal hyphae.

main soil services description linked to soil microbiota. Therefore, to benefit from soil ecosystem services depends on soil biodiversity, which contributes to the capacity of soil to function. Soil functions assure and sustain plant and higher trophic levels of healthy development, as well as air and water quality. At moment, based soil functions in that soil microbiota are involved, acknowledged their potential implication in regulating, supporting, and provisioning services.
