**3.1 Regulating services**

*Regulating services*, generated or intermediated by soil microbiota include in high proportion soil ecosystem processes related to climate regulation; water purification

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

and cycle regulation; pest, pathogens, and diseases control; and bioremediation (e.g., degradation of organic pollutants). *Climate regulation* is mainly mediated by soil bacteria and fungi as they are involved in processes of C exchange between land and atmosphere. Soil as a global carbon sink relies on plants to fix atmospheric carbon and soil microbiota to convert that carbon into the soil. Consequently, soil microbiota excites carbon sequestration and storage through essential interactions with plants. Plant growth and plant biomass could be positively stimulated through nutrient solubilization and phytohormone production and regulation, processes mediated by soil bacteria and fungi. Moreover, soil microbiota are involved in soil structure formation and maintenance through aggregate formation, physically defend the decomposition of soil organic carbon. Conversely, soil microbiota are acknowledged in direct implication in soil organic matter decomposition, which leads to greenhouse gases emission into the atmosphere. Overall, soil microbiota plays an essential role in regulating the global carbon cycle. Soil carbon store and emission depend on land use and applied management practices. Therefore, soil climate regulation depends on that. Studies are divided into two, based on the potential effects of climate change on soil microbiota and their functions related to climate regulating services. The acceleration of heterotrophic microbiota activities rate is correlated positively with an increase in temperature. This was, first, considered to be a positive effect [61]. However, heterotrophic microbiota respiration under aerobic condition increases with temperature rise. Capek et al., [62] described that this will also increase soil organic carbon stock depletion. Loss of soil organic carbon was associated with significant climate feedback effects, such as rising CO2 and CH4 level in the atmosphere. In turn, Drigo et al., [63] showed that a higher CO2 level damaged soil bacterial community structure. The level at which bacterial community is damaged depends on the cover plant type and nutrient availability in the soil. These depend most of the time on soil management practices. Moreover, several agricultural practices are associated with a higher CH4 and N2O emissions, both contributing further to climate change amplitude increase.

*Water regulation and purification*, implying soil microbiota, is assured through their degradation ability of various contaminants. Almansoory et al., [64] showed that *Serratia marcescens* can degrade total petroleum hydrocarbons from soil. *Pseudomonas sp*. degrade in soil herbicides as diuron. Song et al., [65] presented in their paper that *Rhizobium* bacteria degrade di-(2-ethylhexyl) phthalate. Soil bacteria could modify soil organic matter quality and quantity. This could change the water infiltration rate. Therefore, that could be also considered as an indirect effect of soil bacterial communities' influence on water regulation and purification services. *Diseases and pest regulation* by soil microorganisms could be assured through different mechanisms such as antagonism, competition, interference with pathogen signaling, or stimulation of host plant defenses [66]. Plants are often exposed to potential pathogens (e.g., *Erwinia*, *Pectobacterium*, *Pantoea*, *Acidovorax*, *Xanthomona*, etc.) that could cause leaf spots and blights, wilts, overgrowths, scabs, loss of fruits or even of species. Contrarily, the most efficient and dynamic bacteria that could suppress the development of diseases are those that belong to *Firmicutes, γ*- and *β*- *Proteobacteria*. Among fungi, *Ascomycota phylum* is the most representative.

*Soil organic waste and xenobiotics biodegradation* are assured by soil microbiota through processes such as transformation, mineralization, and stabilization. In order that these processes to take place favorable conditions are required. Generally, soil microbiota could use chemicals as substrate resources (energy, C, N, other nutrients, etc.) or could transform them by consecutive microbial enzymes or cofactors (co-metabolism) [66]. Microorganisms could adapt to contaminants; thus, the

contaminant could promote their development. Microbiota in turn could tolerate or degrade contaminants (due to homeostatic capacity). The degradation capacity of microorganisms could be enhanced by supplemental nutrients/amendments addition, augmentation of degrading, or by promoting rhizosphere microbial degradation activity.

#### **3.2 Supporting services**

*Supporting services* are not directly used by humans, although they underpin soil ecosystem functions and processes on which humans depend. Soil microbiota are mainly involved in soil formation, nutrient cycling, water cycling, primary production, and habitat for biodiversity. All of these are related with supporting. Both bacteria and fungi are involved in supporting soil aboveground biodiversity through involvement in catabolic reactions throughout C and nutrients cycles are either break down, mineralized, or transformed. Bacteria that belong to *Actinobacteria*, *Proteobacteria*, and *Firmicutes* were reported to produce organic compounds that have influence on plant root system proliferation. Atmospheric N fixation is provided by free-living bacteria (*Azotobacter, Bacillus*, etc.). Higher available iron-chelating compounds are produced by bacterial species such as *Pseudomonas and Frankia*,. Dimkpa et al., [67] reported that species belonging to *Streptomyces* have the potentials for biofertilization, while *Agrobacterium sp*., *Bacillus sp*., and *Penicillium sp.,* possess phosphate-solubilizing capabilities. Recent studies show that plant rhizobacteria can smooth abiotic stresses related with global change drivers (drought, soil salt intrusion, extreme temperature, poor nutrient availability, contaminants, etc.).

#### **3.3 Provisioning services**

*Provisioning services* of soil ecosystems refers to goods that humans can use and benefit immediately. These are food, water, fiber, fuel, genetic resources, chemicals, medicines, and pharmaceuticals. Soil microorganisms are an important bioresource for several bioactive substances (antibiotics, biosurfactants, enzymes) [66]. They also mediate and facilitate several reactions and soil functions that the promote provision of mentioned soil goods. The complexity of linkages between soil functions (most mediated by communities of soil microbiota) and provided ecosystem services as well as their interrelations is given in **Figure 2**.
