PHOSPHATE SOLUBILIZERS
INTRODUCTION
Phosphate SOLUBILIZERS are a group of beneficial micro-organisms capable of breaking down of organic and inorganic insoluble phosphorous compounds to soluble P form that can easily be assimilated by plants.
Phosphorous (P) is a major growth-limiting nutrient, Plants acquire phosphorus from soil solution as phosphate anion.
TYPES
MECHANISM
ISOLATION
INOCULANT PRODUCTION
INOCULANT APPLICATION
ROLE OF PHOSPHATE SOLUBILIZERS
2. INDEX
• INTRODUCTION
• TYPES
• MECHANISM
• ISOLATION
• INOCULANT PRODUCTION
• INOCULANT APPLICATION
• ROLE OF PHOSPHATE SOLUBILIZING BACTERIA
3. INTRODUCTION
• PHOSPHATE SOLUBILIZING MICROORGANISM(PSMs) are
a group of beneficial micro-organisms capable of
breaking down of organic and inorganic insoluble
phosphorous compounds to soluble P form that can
easily be assimilated by plants.
• Phosphorous (P) is a major growth-limiting nutrient,
Plants acquire phosphorus from soil solution as
phosphate anion.
• they are associated with the plant rhizosphere, so they
are called as rhizobacteria. been termed plant growth
promoting rhizobacteria(PGPR).
phosphate anions
are extremely
reactive and may
be immobilized
through
precipitation with
cations such as
Ca2+ , Mg2+ , Fe3+
and Al3+
4. • P is highly insoluble and unavailable to plants
• Different bacterial species to solubilize insoluble inorganic phosphate
compounds, such as tricalcium phosphate, dicalcium phosphate,
hydroxyapatite, and rock phosphate.
• used as biofertilizers or control agents for agriculture improvement
TYPES OF PSB
Bacterial
genera
Fungal genera Actinomycetes
Arbuscular
mycorrhizal(A
M)
5. MECHANISMS OF PHOSPHATE SOLUBILIZATION
• It includes the production of organic acids, and acid phosphatases play a major
role in the MINERALIZATION of organic phosphorus in soil.
• Production of organic acids results in acidification of the microbial cell and its
surroundings
• Gluconic acid and 2-ketogluconic acid seems to be the most frequent agent with
phosphate solubilizing ability.
Organic acid Strains
2-Ketogluconic acid Rhizobium leguminosarum, Rhizobium meliloti,
Bacillus firmus
Gluconic acid Pseudomonas sp., Erwinia herbicola, Pseudomonas
cepacia, Burkholderia cepacia
: Microbial strains producing organic acid
6. Strains of Bacillus were found to produce mixtures of lactic, isovaleric, iso-butyric
and acetic acids
Other organic acids, such as glycolic, oxalic, malonic, and succinic acid, been
identified among phosphate solubilizers.
Chelating substances and inorganic acids such as sulphideric, nitric, and carbonic
acid are phosphate solubilization
Genera Pseudomonas,
Bacillus and
Rhizobium are among
the most powerful
phosphate solubilizers
7. ISOLATION OF PHOSPHATE
SOLUBILIZING.BACTERIA
Using plate screening methods
Phosphate solubilizers produce clearing
zones around the microbial colonies in
media.
Insoluble mineral phosphates such as
tricalcium phosphate or hydroxyapatite
are contained in the media
bromophenol blue method that
produce yellow halos following pH drop
through the release of organic acids
NOTE:
Clearing zones on agar
plate method is
generally used
Pikovskays’s medium is
a general medium for
selection of phosphate
solubilizer
:Phosphate solubilizer
forming clear zone by Fungi
8. Inoculant Production
STEP-1 CULTIVATION
-Media: proper media for inoculant (nutrient broth, yeast extract
broth etc.)
-Incubation condition: temperature, light, incubation period
STEP-2 COLLECTION
-After incubation period, collect microbial cells by centrifuge
-Wash cells with distilled water or diluted saline solution
STEP-3 FORMULATION OF INNOCULATION USING CARRIER
MATERIALS
-Mix cells using carrier materials such as peat, vermiculite, perlite
Potential materials that are able to support good growth and survival of
bacteria including different types of COALS, BENTONITE, CORN OIL,
MINERAL SOILS, PEAT, PEAT MOSS, VERMICULITE, AND PERLITE
Cultures centrifuged
