The basic knowledge about the plant growth Promoting rhizobacteria in phytoremediation.

1. VIVEKANANDHA ARTS AND
SCIENCE COLLEGE FOR WOMEN,
Veerachipalayam, Sankari, Salem.
DEPARTMENT OF MICROBIOLOGY
SUBJECT: BIOREMEDIATION
P.DIVYA
I- M.SC MICROBIOLOGY
VIVEKANANDHAARTS AND SCIENCE COLLEGE FOR
WOMEN,
VEERACHIPALAYAM, SANKARI, SALEM.
GUIDED BY :
DR.R. DINESH KUMAR,
ASSISTANT PROFESSOR ,
DEPARTMENT OF MICROBIOLOGY,
VIAAS, SANKARI, SALEM.
PLANT GROWTH PROMOTING RHIZOBACTERIA
IN PHYTOREMEDIATION

2. • Introduction
• Categories of PGPR
• Characteristics of PGPR
• Mechanisms of actions of PGPR
• Role of PGPR in Phycoremediation
• Commercialization of PGPR
• Conclusion
CONTENT

3. Introduction
• The word plant growth promoting rhizobacteria ( PGPR) was proposed by
kloepper et al.,1980.
• PGPR are the rhizosphere bacteria that can enhance the plant growth.
• Rhizosphere is the zone of soil surrounding a plant root where the biology
and chemistry of the soil are influenced by the root.
Plant growth promoting rhizobacteria in phytoremediation

4. Categories Of PGPR
They are categorized into two major groups.
Intracellular PGPR :
• Symbiotic rhizobacteria which invade the interior/ inside of the cell. eg:
nodule bacteria
Extracellular PGPR :
• Free living rhizobacteria that exist outside the plant cells.eg:
Bacillus, Pseudomonas.

5. Characteristics Of PGPR
• Promote the plant growth
• Promote the plant protection activities.
• Survive and multiply microhabitats associated with root surface, In
competition with other microbiota.
• Able to colonize the root.

6. Mechanisms Of Actions Of PGPR
Direct Indirect
1. Nitrogen fixation
2. Phosphate solubulization
3. Siderophore production
1. Antibiotic production
2. Nutrients and niche competition
3. Induced systemic resistance

7. Direct plant growth promotion
1. Nitrogen fixation
• Nitrogen is a vital element for all forms of life, It is the most
important nutrient for plant growth.
• Nitrogen is an essential constituent of nucleotides, membrane
lipids and amino acids.
• The biological fixation of atmospheric nitrogen is an important
microbial activity for the maintenance of life on earth through
photosynthesis performed by photosynthetic organisms

8. PGPR fix atmospheric nitrogen and provide it to plant by two
mechanisms.
• Symbiotic nitrogen fixation: The mutual relationship between plants and
the organisms. eg: Frankia.
• Non symbiotic nitrogen fixation: It is carried out by free living
diazotrophs.eg:Azospirillium, Azotobacter.

9. 2.Phosphate solubulization:
• Phosphate is next to nitrogen in the list of essential minerals mostly required by
plants, However there deficiency in soil limit plant growth in a number of ways.
• It's an insoluble inorganic element which increase the economic
viability of any agricultural product when solubilized
• The organic forms are found mostly in humans and decayed
materials.
Eg: Arthrobacter, Pseudomonas, Bacillus.

11. 3.Siderophore production
• Iron is a vital element needed by all forms of life. It one of the
most abundant mineral deposit on earth.
• Siderophore are low molecular weight biomolecules produced by
microorganisms.
• Siderophore are secreted to solubulize iron from their surrounding
environment forming a complex ferric siderophore that can move by
diffusion and be returned to the cell surface.
• Microbial siderophore enhance iron uptake by plants that are able to
recognize the bacterial ferric siderophore complex.

12. Indirect plant growth promotion
1.Antibiotic production
• Antibiotic production is one of the most studied biocontrol
strategies display by PGPR.
• A good example include amphibian, oomycin A,
phenazine, tensin.
• These biochemical are produced by pseudomonas
strains.
• Antibiotics are low molecular weight compound that supress the
development of plant pathogenic microorganisms.

13. 2.Nutrients and niche competition
• For rhizospheric bacteria to claim dormant over the rest of soil
microorganisms it must be able to compete favorably for the available
nutrient and space.
• A vital strategy needed to limit the incidence and severity of
plant disease.
• In niche competition, a physical occupation of site by PGPR is enhanced
through delay tactics, by preventing the colonization of pathogens until the
availabe substrate is exhausted.

14. 3. Induced systemic resistance
• PGPR trigger inducement of some kind of defense
system that is capable of fighting some pathogenic
bacteria , fungi, and viruses.
• Induce systemic resistance ( ISR) utilize organic acid and
plant hormones ( salicylic acid, jasmonic acid and ethylene)
in plants signaling and stimulation of the host plant defense
response against variety of plant pathogens.

15. Role Of PGPR in Phytoremediation
• As soil constantly welcome large inflow of waste and
contaminated materials, they overtime have stern impact on the
environment and human health.
• Most common of these pollutants are heavy metals ( Hg,
Pb, Cr, Co, Zn, Ni,and cd).
• They have been attributed to industrialization, Urbanization and
civilization.

16. • In agricultural development soil pollution has implicated human
activities such as excessive fertilizer application, indiscriminate disposal
of sewage and municipal waste and pesticides/ insecticides usage.
• Soil rhizobacteria assisted phytoremediation has become an
alternative of choice in detoxifying sites because its cost effective,
eco-friendly and aesthetic.
• Decontaminating these heavy metals polluted soil occur
through chelation, solubulization and mineralization using large
consortium of soil microorganisms residence in the
rhizosphere.

17. Commercialization Of PGPR
• The success and commercialization of plant growth promoting
rhizobacteria strains depends on the linkages between the scientific
organization and industries.
• Commercial success of PGPR strains requires economical and viable market
demand, safety and stability, low capital costs and availability of carrier
materials.

19. Conclusion
• PGPR is very essential for plant growth.
• Their productive efficiency can be enhanced by improving
soil conditions.
• Replace chemical fertilizer and pesticides which have many bad
effects on agriculture.