Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that actively colonize plant roots and increase plant growth and yield . Plant growth promoting rhizobacteria (PGPR) were first defined by Kloepper and Schroth

1. By,
Pooja Walke

2. Five strains of rhizobacteria were isolated from sugarcane (Saccharum
officinarum) rhizosphere of Pimpalgaon region on King’s B medium. These strains
were designated as SI, SII, SIII, SIV and SV .
SI, SII and SIII strains were identified as species of Bacillus and strains SIV
and SV were identified as Pseudomonas fluorescens.
These strains when used as inoculants both individually and as mixture of
five strains for seed bacterization resulted in enhanced germination where
compared to individual PGPR strain the germination was more in all five strains
mixture.
In the experiment of plant growth promotion for wheat, subsequent
increase in growth of shoot length was observed, application of mixture of strains
resulted with notable increase in growth compared to the individual strain.
These strains as SI, SII, SIII, SIV and SV were capable of causing phosphate
solublization. Cell wall degrading enzyme activities such as casein hydrolysis and
cellulose degradation. All five strains were positive for casein hydrolysis where SII
and SIV strains were positive for cellulase production.

3.  Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that actively
colonize plant roots and increase plant growth and yield . Plant growth promoting
rhizobacteria (PGPR) were first defined by Kloepper and Schroth .
 The ability of a PGPR to establish in the rhizosphere is referred to as
rhizocompetence .
 The rhizosphere-associated beneficial bacteria consist of the genera like
Pseudomonas , Bacillus, Azospirillum, Enterobacter, Acetobacter, and Azotobater
etc, as well as many unidentified rhizosphere isolates.
 PGPR are free-living, soil-borne and belong to heterogeneous group of bacteria.
 Direct mechanisms by PGPR, include nitrogen fixation, production of plant
hormones, Phosphate solubilization .
 Indirect mechanisms used by PGPR include antibiotic production against
pathogenic bacteria, siderophores production synthesis of cell wall degrading
enzymes etc.

4. AIM
 The aim of this study was to observe activity of
PGPR strains individually and in mixture.
 Compared to the use of individual PGPR strains,
mixtures of several strains can result in:

5. 1. Collection of Sample
2. Isolation of PGPR
3. Identification of PGPR
3.1 morphological characteristics
3.2 biochemical characteristics
4. Plant growth promotion experiment
5. Seed Bacterization
6. Plant growth promotion activities by
PGPR:
6.1 Phosphate Solubilization
6.2 Cell Wall degrading enzyme activity
6.2.1 Cellulase production test
6.2.2 Casein hydrolysis

6. Isolation code Gram’s nature Morphology
S I Gram positive Rod
S II Gram positive Rod
S III Gram positive Rod
S IV Gram negative Rod
S V Gram negative Rod
Identification of PGPR

7. Isolate code Pigmentation Oxidase Test Endospore
staining
Starch
Hydrolysis
S I - + + +
S II - + + +
S III - + + +
S IV + + - -
S V + + - -

8. Isolate code Germinated seeds Ungerminated
seeds
Percentage (%) of
Germination
S I 3 1 75%
S II 2 2 50%
S III 3 1 75%
S IV - - -
S V 4 0 100%
SI + SII +SIII + SIV
+ SV
4 0 100%
CONTROL 2 2 50%

9. Isolatate code No. of days/ Length of shoot (cm) AVERAGE
1 2 3 4 5 6 7 8
S I - 0.9 1.9 4.3 7.3 9.7 15.6 17.1
S II - - - - - 2.3 4.9 6.7
S III - - 0.5 1.3 1.9 4.2 6.2 7
S IV - - - - 0.9 0.5 4.2 6.5
S V - - 0.3 0.2 0.7 1.2 1.7 2.2
SI + SII +SIII - 0.6 1.2 4 5.7 9.5 15.9 18.4
SII +SIII + SIV - 0.4 1.6 4.7 6 8.9 12.3 16
SIII + SIV + SV - 0.1 0.2 1.7 4.8 5 9.8 12.3
SI + SII +SIII + SIV + SV - - 0.3 1.7 4.2 10.2 17 18.6
CONTROL - 0.3 0.5 1.0 1.8 2.8 4.2 6.6

10. Isolatate code Phosphate
Solubilizing
Test
Cellulase
Production
Test
Casein
Hydrolysis
Test
S I + - +
S II + + +
S III + - +
S IV + - +
S V + + +

11.  In this study, we have investigated the effectiveness of PGPR, whether they
could increase seed germination rate as well as growth of seedlings. Most of
the isolates significantly increased, growth of shoots in terms of shoot
length has been observed.
 The positive effects of PGPR strains were explained by phosphate
solublizing capacity and biological control of plant pathogen and
deleterious microorganisms through production of cell wall degrading
enzymes such as cellulose and protease
 Numerous studies have indicated that PGPR have great potential in
biocontrol and plant growth promotion but most of the studies focus on
plant growth promotion by using single/ individual strains.
 To develop further beneficial inoculants for field study, one approach
should consider inoculation assays with a consortium containing a mixture
of soil organism instead of single organisms. Multiple organisms may
enhance the level and consistency of plant growth promotion by a more
stable rhizosphere community and effectiveness over a wide range of
environmental condition.

12.  A. Gholami, S. Shahsavani, and S. Nezarat (2009) The Effect
of Plant Growth Promoting Rhizobacteria (PGPR) on
Germination, Seedling Growth and Yield of Maize. World
Academy of Science, Engineering and Technology 49
 B. Joseph*, R. Ranjan Patra, R. Lawrence (2007),
Characterization of plant growth promoting rhizobacteria
associated with chickpea (Cicer arietinum L.) International
Journal of Plant Production 1(2)
 K. V. B. R. Tilak1 et. al.(2005) Diversity of plant growth and
soil health supporting bacteria urrent science, VOL. 89, NO. 1
 M. Lucy, E. Reed and Bernard R. Glick(2003) Applications of
free living plant growth-promoting rhizobacteria, Antonie van
Leeuwenhoek 86: 1–25, 2004.
 V. Ramamoorthy, R. Viswanathan, T. Raguchander, V.
Prakasam, R. Samiyappan, (2000) Review article: Induction of
systemic resistance by plant growth promoting rhizobacteria in
crop plants against pests and diseases. Crop Protection 20