102
S. A. El.-M. M. Abd El-Azeem
wastes and soil pollution and provide the plant with available nitrogen simultaneously
[30].
Plant growth promoting rhizobacteria, mycorrhizal fungi and phosphate solubilizing bacteria are applied as biofertilizers, biocontrol agents and/or phytostimulators
in Egyptian agricultural system. These microorganisms can be colonized plant roots
and promoted plant growth and yield as well as increased nutrients availability in
soils especially N and P [31, 9, 7]. In soils with a low P bioavailability such as Egyptian soils, free-living P-solubilizing bacteria could release P ions from sparingly
soluble inorganic and organic P compounds, and thereby contribute to an increase
in the soil P pool that is available for the extraradical mycelium of the arbuscular
mycorrhizal fungus and that can be transferred to the host [32, 33]. Unfortunately,
soil enzyme activities and biochemical processes in agricultural soils will impact by
climate change especially in arid climatic regions. Also, climate change affects the
performance of plant growth promoting microorganisms. In the following section,
we will describe the response of microbial activity to changes in temperature, CO 2
concentration, moisture content and salinity.
3 Response of Microbial Activity to Climate Change
Egypt is mostly located in the region that is highly vulnerable to climate change
impact. Additionally, it is typically lack technological expertise and financial
resources for adaptation to climate change or its mitigation. The impact of climate
change on beneficial plant-microbe interactions has recently received considerable
attention [34]. In the following sections, we discuss the effect of climate changes
such as temperature, elevated CO 2 , soil moisture content and soil salinity on Egyptian
soil microbial activities like the population of soil microorganisms, soil microbial
biomass and respiration, and soil microbe-plant interactions.
3.1 Effect of Temperature
Natural and/or anthropogenic activities increased atmospheric CO 2 levels, resulting
in increased the temperature of the global surface about 1.8 and 3.6 (4–7) °C by the
year 2100 [35]. For instance, increased temperature by 5 °C in a temperate region
changed the relative abundances of soil bacteria and increased the bacterial to the
fungal ratio (B/F ratio) of the community [36]. As the climate warms, the populations
of soil microorganisms must adapt or die. In the soil microclimate, soil temperature
can influence on enzyme pool sizes through their effect on the activity of enzymes,
microbial efficiency and availability of substrate. Therefore, the overall and specific
rate of enzyme production and the relative rate of various soil enzymes will also be
affected as soil temperature increase [37]. According to Stone et al. [38] the activity of
S. A. El.-M. M. Abd El-Azeem
wastes and soil pollution and provide the plant with available nitrogen simultaneously
[30].
Plant growth promoting rhizobacteria, mycorrhizal fungi and phosphate solubilizing bacteria are applied as biofertilizers, biocontrol agents and/or phytostimulators
in Egyptian agricultural system. These microorganisms can be colonized plant roots
and promoted plant growth and yield as well as increased nutrients availability in
soils especially N and P [31, 9, 7]. In soils with a low P bioavailability such as Egyptian soils, free-living P-solubilizing bacteria could release P ions from sparingly
soluble inorganic and organic P compounds, and thereby contribute to an increase
in the soil P pool that is available for the extraradical mycelium of the arbuscular
mycorrhizal fungus and that can be transferred to the host [32, 33]. Unfortunately,
soil enzyme activities and biochemical processes in agricultural soils will impact by
climate change especially in arid climatic regions. Also, climate change affects the
performance of plant growth promoting microorganisms. In the following section,
we will describe the response of microbial activity to changes in temperature, CO 2
concentration, moisture content and salinity.
3 Response of Microbial Activity to Climate Change
Egypt is mostly located in the region that is highly vulnerable to climate change
impact. Additionally, it is typically lack technological expertise and financial
resources for adaptation to climate change or its mitigation. The impact of climate
change on beneficial plant-microbe interactions has recently received considerable
attention [34]. In the following sections, we discuss the effect of climate changes
such as temperature, elevated CO 2 , soil moisture content and soil salinity on Egyptian
soil microbial activities like the population of soil microorganisms, soil microbial
biomass and respiration, and soil microbe-plant interactions.
3.1 Effect of Temperature
Natural and/or anthropogenic activities increased atmospheric CO 2 levels, resulting
in increased the temperature of the global surface about 1.8 and 3.6 (4–7) °C by the
year 2100 [35]. For instance, increased temperature by 5 °C in a temperate region
changed the relative abundances of soil bacteria and increased the bacterial to the
fungal ratio (B/F ratio) of the community [36]. As the climate warms, the populations
of soil microorganisms must adapt or die. In the soil microclimate, soil temperature
can influence on enzyme pool sizes through their effect on the activity of enzymes,
microbial efficiency and availability of substrate. Therefore, the overall and specific
rate of enzyme production and the relative rate of various soil enzymes will also be
affected as soil temperature increase [37]. According to Stone et al. [38] the activity of