ABSTRACT- The isolation of phosphate solubilizing bacterial strains exhibiting high ability to solubilize soil
phosphorus is a matter of great interest with high applicability. The use of phosphate solubilizing bacteria as inoculants
simultaneously increases phosphate uptake by the plant and increase crop yield. Strains from the genera
Pseudomonas,
Bacillus and
Rhizobium species are among the most powerful phosphate solubilizers. In this present study different
cultivated soil samples were investigated for the isolation of phosphate solubilizing bacteria by Pikovskayas agar media.
We were found 2 bacterial strains SS1 and SS2 as a phosphate solubilizing bacteria. Both two bacteria are characterized
by morphological and biochemical tests. The strain SS2 was confirmed as a
Bacillus megaterium. Then
Bacillus
megaterium is used for the production of longer sustainable phosphate solbulizing biofertilizer. After an interval of 180
days it has 5x1013 CFU count.
Key-Words- Phosphate solubilization; Soil bacteria; Plant-growth-promoting bacteria;
Rhizobacteria; Phosphates;
Biofertilizer
INTRODUCTION-
Bacillus megaterium was discovered and described [1] in
1884.
Bacillus megaterium was used by Lwoff and
Guttman in the studies that discovered lysogeny.
Bacillus
megaterium is one of the first bacteria's genome that has
been fully coded.
Bacillus megaterium is a biological
fertilizer based on a selected strain of naturally-occurring
beneficial eubacteria
Bacillus megaterium.
Bacillus megaterium is a gram positive, rod shaped, endospore
forming bacteria. It is used as an effective soil inoculant.
Bacillus megaterium have ability to solubilize phosphorus,
which is good for plant. Phosphorus plays a significant role
in several physiological and biochemical plant activities
like photosynthesis, transformation of sugar to starch,
transporting of the genetic traits [2]. To achieve a high-yield in agriculture, it is necessary to
apply phosphorus fertilizers that deliver the nutrients to
plants [4]. However, the production of phosphorus fertilizer
is a costly process that requires use of nonrenewable
phosphate resource (phosphorite), mineral acids (sulfuric
acid) and generates many environmental hazardous
byproducts [5-6].
Phosphorus solubilizing microorganisms are ubiquitous in
soils and could play an important role in supplying
phosphorus to the plants [7]. The principal mechanism for
mineral phosphate solubilization is the production of
organic acids, and acid phosphatases play a major role in
the mineralization of organic phosphorous in soil by
Ahmad Ali Khan [8]. Microorganisms also solubilize
sparingly soluble phosphates by decreasing the pH of the
surrounding environment or acting on the calcium, iron,
aluminum, and magnesium salts. In rice plantations, for
example, a large amount of organic acids is generated, this
increasing phosphorus availability to wheat [9].
Bacillus megaterium var. phosphaticum was used to create a
bio-preparation called Phosphobucterin with the purpose of
enhancing mineral phosphorus solubilization [10]. If
phosphorus is present in the complex structures of the soil
and, at the same time, readily decomposable carbon sources, such as manure, are incorporated in the soil,
phosphorus solubilization can be increased due to
biological activity stimulation. This organic carbon increase
may aid to complexing the soila luminum in acids, thus
reducing the aluminum phosphate. Taking into account that
the isolation of bacterial strains exhibiting high potential of
soil phosphorus solubilization has been little studied in
Romania, we believe it would be useful to approach this
subject of great interest and practical applicability.
Approximately 90% to 95% phosphorus formed in soil is
present in insoluble forms [11], which are not utilized by
plants, so phosphorus solubilizing bacteria play an
important role to solubilize phosphorus,
P. vazquez [12].
MATERIALS AND METHODS-
This project is performed in Microbiology section of
Chaperon Biotech Pvt. Ltd, Kanpur, India for duration of 8
Months. Isolation of
Bacillus megaterium bacteria from soil
sample was done on Pikovskayas agar media by dilution
plate technique. Detection and estimation of the phosphate
solublization ability of microorganisms have been possible
using plate screening method. 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.
The phosphate solubilizing bacteria is isolated for further
identification by morphological & biochemical analysis.
The morphological tests performed are Gram Staining &
Endospore staining. The biochemical analyses performed
were Catalase test, Starch hydrolysis test, Citrate hydrolysis
test, Methyl red test, Vogous proskar test, Casein hydrolysis
test, Indole test, Gelatine hydrolysis test, Urease hydrolysis
test, Mannitol fermentation test, Carbohydrate fermentation
test, and Salinity test etc. is shown in Table 1. The
biofertilizer is prepared by immobilizing the bacterial cell
and kept for 36 hours at 370C on rotatory shaker. After
immobilization the bacterial culture is added to carrier i.e.
charcoal and preserved for further use.
Flow chart of Production of Biofertilizer from Bacillus
Megaterium
Table-1 Biochemical Characterization of samples
S.
No. |
BIOCHEMICAL TEST |
SAMPLE
1 (SS1) |
SAMPLE
2 (SS2) |
1. |
Catalase test |
(+)ve |
(+)ve |
2. |
Starch hydrolysis test |
(+)ve |
(-)ve |
3. |
Citrate hydrolysis test |
(-)ve |
(+)ve |
4. |
Methyl red test |
(-)ve |
(-)ve |
5. |
Vogous proskauer test |
(+)ve |
(-)ve |
6. |
Casein hydrolysis test |
(-)ve |
(+)ve |
7. |
Indole test |
(-)ve |
(-)ve |
8. |
Gelatine hydrolysis test |
(-)ve |
(-)ve |
9. |
Urease hydrolysis test |
(-)ve |
(-)ve |
10. |
Mannitol fermentation test |
(+)ve |
(+)ve |
11. |
Carbohydrate
fermentation test |
(-)ve |
(-)ve |
12. |
Salinity test |
(+)ve |
(+)ve |
RESULTS-
The bacterial cultures were isolated from soil sample
collected from IPR and Mandhana, Kanpur, India. The
bacterial samples were identified by morphological and
biochemical tests for the presence of phosphate solbulizing
bacteria then all the isolates were subjected to various
testes for confirming their identity. All the check isolated
and standard strains formed completely white, round,
smooth and shiny colonies. During microscopic
observation all the isolates were found to be gram positive
and rods shape. Presence of endospores was confirmed by
endospore staining and all the isolated bacteria were
subjected to various biochemical tests for the confirmation
of their identity. Bacterial samples (SS1& SS2) shows clear
zone into the Pikovskayas agar media, so it is confirmed
that bacterial sample (SS2) is
Bacillus megaterium
organism. Test is positive so that immobilized bacterial
culture is added in to carrier i.e. charcoal. The cell count of
Bacillus megaterium is determined by colony counting in
an interval of 1 to 180 Days .e. mentioned in Table 2.
Fig 1. Serial dilution plate on Pikovskayas agar media
Table-2 Biofertilizer cell count at different time interval
Time interval (Days) |
Per gram of biofertilizer contains
Bacterial Cell count (CFU) |
0 |
11 x 1013 |
7 |
10.9 x 1013 |
30 |
10.5 x 1013 |
60 |
8 x 1013 |
180 |
5 x 1013 |
Fig 2. Biofertilizer cell count at different time interval
DISCUSSION-
The phosphatic fertilizer in current use requires a greater
input that cannot be afforded by the farmers of the
developing nations. Approximately 90% to 95%
phosphorus formed in soil is present in insoluble forms that
is not available for crop.[7] Microbiologists and soil
scientists thus have a responsibility to society to find ways
and means of making phosphorus available to crops, an
economically efficient substitute for fertilization of crops.
The solubilization of phosphatic compounds by naturally
abundant PSM is very common under in vitro conditions [9].
Since most soils are deficient in plant-available phosphorus
and chemical fertilizers are not cost-effective, there is
interest in using rhizosphere competent bacteria (RCB) or
soil microorganisms endowed with phosphate-solubilizing
ability as inoculants to mobilize phosphate from poorly
available sources in soil [10]. Although potential clearly
exists for developing such inoculants, their widespread
application remains limited by a poor understanding of
microbial ecology and population dynamics in soil, and by
inconsistent performance over a range of environments.
Furthermore, promotion of growth of agronomically
important plants, as a consequence of microbial
inoculation, may not necessarily be associated with
characteristics such as phosphate solubilization, which are
manifest under laboratory conditions. Further, in order to
ensure food security in developing countries, there is an
urgent need for the sustainable intensification of
agricultural production systems towards supporting
productivity grains and income generation. In this context,
novel, genetically-modified soil and region specific PSM
and technologies for their ultimate transfer to the fields
have to be developed, pilot-tested and transferred to
farmers in a relatively short time [11]. In the present study
many bacteria are isolated from soil among them two are
predicted as
B. megaterium by colony morphology. Then
these strain SS2 is identified as
B. megaterium by
biochemical test. Then
B. megaterium is use for the
production of solid biofertilizer.
CONCLUSION-
The present study deals with the production of
phosphate dissolving
B. megaterium as biofertilizer. It
shows that strain SS2 was confirmed as a
Bacillus
megaterium species. It reviles that the
B. megaterium has
the ability to solubilize the free phosphate.
Charcoal is used as carrier for the production of
biofertilizer and it has the ability to give proper
nutritional supply to the bacteria to carry on its life. The
Cell count in the biofertilizer is also adequate after 6
months i.e 5 x 1013 CFU. Since the cell count is so good
after 6 months than
B. megaterium with charcoal can be
used commercially.
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