Recently, the agriculture and industries have released lot of chemical wastes as
xenobiotics, which is very harmful to human growth, crops, livestock and wild life.
Various methods like bioremediation offer to destroy the harmful things by using the
natural materials (Fulekar 2014). Bioremediation and phytoremediation are widely
emerging technologies used to eliminate the contaminants from soil and water
(Raskin and Ensley 2000). The microbial products also help to destroy the pollutants
from soil (Vidali 2001). Microbial metabolites like proteins and enzymes are used to
breakdown the contaminants from soil through the mutualistic relationship with the
plants (Fulekar 2014).
1.4 Plant Physiological Effects on Rhizosphere Enzyme
Activity
Root is a major vegetative organ that supply water, minerals and substances essential
for plant growth and development. Roots are believed to be the primary source of the
growth regulators gibberellins and cytokinins, which influence the overall plant
growth and development. The rhizosphere is a unique hotspot in soil from the
viewpoint of microbial ecology, as soil microorganisms are considerably stimulated
by the activity of the roots.
Increased soil temperatures, elevated atmospheric carbon dioxide and more
frequent wetting and drying cycles (water stress) will change microbial community
composition and possibly increase biomass and enzyme activities either directly or
stimulation of plant growth and increases in litter deposition and root exudation. The
climate is changing as the concentrations of CO 2 and other greenhouse gases in the
atmosphere increase, resulting in global warming and altered precipitation patterns.
Because the activities of enzymes in natural environments are controlled by both
abiotic factors (e.g. temperature, water potential and pH) and biotic processes
(e.g. enzyme synthesis and secretion), they are likely to be responsive to atmospheric
warming and more frequent and extreme variations in precipitation patterns. These
changes will have important consequences for ecosystem functions such as decomposition, nutrient cycling and plant microbe interactions, which will ultimately affect
plant growth and productivity.
The study of different hydrolase enzyme activities in the rhizosphere soil and
their changes is important in plant growth and development. Since they indicate the
potential of a soil to carry out specific biochemical reactions, and these hydrolytic
enzymes are important in maintaining soil fertility and plant productivity. Because
plant nutrient uptake occurs through the rhizosphere, the activity of rhizosphere
microbial community is of great importance for plant growth.
Soil enzymes are involved in the catalysis of a large number of reactions
necessary for life processes of microorganisms in soils, decomposition of organic
residues, cycling of nutrients, formation of organic matter and soil structure. These
enzymes include amylase, arylsulphatases, beta glucosidase, cellulase, chitinase,
1 Rhizosphere: Niche for Microbial Rejuvenation and Biodegradation of Pollutants
7
xenobiotics, which is very harmful to human growth, crops, livestock and wild life.
Various methods like bioremediation offer to destroy the harmful things by using the
natural materials (Fulekar 2014). Bioremediation and phytoremediation are widely
emerging technologies used to eliminate the contaminants from soil and water
(Raskin and Ensley 2000). The microbial products also help to destroy the pollutants
from soil (Vidali 2001). Microbial metabolites like proteins and enzymes are used to
breakdown the contaminants from soil through the mutualistic relationship with the
plants (Fulekar 2014).
1.4 Plant Physiological Effects on Rhizosphere Enzyme
Activity
Root is a major vegetative organ that supply water, minerals and substances essential
for plant growth and development. Roots are believed to be the primary source of the
growth regulators gibberellins and cytokinins, which influence the overall plant
growth and development. The rhizosphere is a unique hotspot in soil from the
viewpoint of microbial ecology, as soil microorganisms are considerably stimulated
by the activity of the roots.
Increased soil temperatures, elevated atmospheric carbon dioxide and more
frequent wetting and drying cycles (water stress) will change microbial community
composition and possibly increase biomass and enzyme activities either directly or
stimulation of plant growth and increases in litter deposition and root exudation. The
climate is changing as the concentrations of CO 2 and other greenhouse gases in the
atmosphere increase, resulting in global warming and altered precipitation patterns.
Because the activities of enzymes in natural environments are controlled by both
abiotic factors (e.g. temperature, water potential and pH) and biotic processes
(e.g. enzyme synthesis and secretion), they are likely to be responsive to atmospheric
warming and more frequent and extreme variations in precipitation patterns. These
changes will have important consequences for ecosystem functions such as decomposition, nutrient cycling and plant microbe interactions, which will ultimately affect
plant growth and productivity.
The study of different hydrolase enzyme activities in the rhizosphere soil and
their changes is important in plant growth and development. Since they indicate the
potential of a soil to carry out specific biochemical reactions, and these hydrolytic
enzymes are important in maintaining soil fertility and plant productivity. Because
plant nutrient uptake occurs through the rhizosphere, the activity of rhizosphere
microbial community is of great importance for plant growth.
Soil enzymes are involved in the catalysis of a large number of reactions
necessary for life processes of microorganisms in soils, decomposition of organic
residues, cycling of nutrients, formation of organic matter and soil structure. These
enzymes include amylase, arylsulphatases, beta glucosidase, cellulase, chitinase,
1 Rhizosphere: Niche for Microbial Rejuvenation and Biodegradation of Pollutants
7