ISOLATION AND SCREENING OF EFFICIENCY OF PHOSPHATE SOLUBILIZING MICROBES

PATIL C.S.¹*, SANJOTHA P.², MAHANTESH P.^3
1Department of Biotechnology B.V.Bhomraddy College, Bidar, Karnataka
²Department of Biotechnology B.V.Bhomraddy College, Bidar, Karnataka
³Department of Biotechnology B.V.Bhomraddy College, Bidar, Karnataka
* Corresponding Author : drcspatil1251@yahoo.co.in, drcspatil1960@gmail.com

Received : 12-03-2011     Accepted : 23-04-2011     Published : 15-07-2011
Volume : 3     Issue : 1       Pages : 56 - 58
Int J Microbiol Res 3.1 (2011):56-58
DOI : http://dx.doi.org/10.9735/0975-5276.3.1.56-58

The soil in the identified saline was investigated for the study of phosphate solublization by fungi and bacteria. In the present study 107 samples were collected from saline affected area, among these samples, 33 (30.80%) samples showed the ability to solubilize the inorganic insoluble phosphate. From the study it was observed that the fungi viz; Aspergillius spp., Penicillium spp. and Fusarium spp. have the more solubilizing ability of inorganic insoluble phosphate than bacteria, viz; B.subtilis, and B.megatherium. Hence the application of biofertilizer prepared by above mentioned fungi should be helpful to reduce the salinity of soil by neutralization phenomenon, because these microorganisms release the acid in very minute quantity in phosphate Solubilization.

Phosphate solubilizing microorganism (PSM), acid production, Pikovskayas agar.

Phosphorus is one of the major plant nutrients, second only to nitrogen in requirement. However, a greater part of soil phosphorus, approximately 95–99% is present in the form of insoluble phosphates and hence cannot be utilized by the plants [1] . To increase the availability of phosphorus for plants, large amounts of fertilizer are used on a regular basis. But after application, a large proportion of fertilizer phosphorus is quickly transferred to the insoluble form [2] . Therefore, very little percentage of the applied phosphorus is used, making continuous application necessary [3] . It has been reported that many soil fungi and bacteria can solubilize inorganic phosphates [4,5] . Phosphate solubilizing microorganisms (PSMs) play an important role in supplementing phosphorus to the plants, allowing a sustainable use of phosphate fertilizers [6,8] . Application of PSMs in the field has been reported to increase crop yield [9,10] . Several mechanisms like lowering of pH by acid production, ion chelation and exchage reactions in the growth environment have been reported to play a role in phosphate solublization by PSMs [11,12] . Fungi have been reported to possess greater ability to solubilize insoluble phosphate than bateria [13] . In the present study fungal strains having potential to solubilize insoluble phosphates were isolated.

Collection of Sample: The soil samples were collected from depth of 6-15cm from different agricultural land of villages of saline affected area of Bidar, Karnataka. Samples were collected from rhizosphere of plant like, Wheat, Jowar, Orange, Sugarcane, Gram, Onion, Sunflower, Tomato, Tur and Cabbage.
Isolation of PSM: Fungal and bacterial strains were isolated from the saline soil of Bidar, Karnataka, after serial dilution of soil solution on potato dextrose agar (PDA) and nutrient agar (NA) respectively. Isolated predominant, morphologically distinct colonies were selected, purified by repeated culturing and maintained on PDA and NA slants at 400C isolates were identified by their colony characteristics, spore morphology and microscopic observations. The isolates were studied for phosphate solubilizing ability on Picovskayas (PKV) medium [14] .
Identification of Fungi and Bacteria: For the identification of fungi, a drop of lactophenol cotton blue placed on glass slide, then growth of fungi has to be taken on the slide and cover with the cello tape to fix the growth on slide, and the slide then observed under low objective microscope and identified based upon their colony morphology and spore characteristics [15] . The isolated bacteria, identified by studying
morphological characteristic in which gram staining, shape, spores and motility including catalase test, glucose, mannitol fermentation and Vogues Proskeurs (VP) test were present [15] . [Table-1] .
Comparative Efficiency Study: Efficiency study has been carried out by performing an experiment of halo zone formation around the fungal and bacterial growth after inoculated on Pikovskayas agar and incubated for 24h, 48h and 72h at 280c [Fig-1] continuous observation, indicates phosphate solubilizing ability which observed by checking diameter of zone which were in increasing order at every day incubation. The zones were then compared to find phosphate solublization efficiency. [Fig-2] shows the comparative efficiency of PSMs for 10 different samples.

In the present study 107 soil samples were collected from different villages of Bidar, Karnataka 33 (30.80%) samples showed presence of PSM. In the advance condition of pH the organisms isolated from salinityaffected soil indicates high salt and salinity tolerance, which can be used for preparation of biofertilizer from locally isolates. From the isolated sample, twenty villages (87%) were found the Aspergillus spp. [Fig-1] , two villages (8.7%) are found Penicillium spp. [Fig-1] and single village (4.3%) was found Fusarium spp. [Fig-1] and ten villages were found the phosphate solubilizing bacteria i.e. Bacillus species, out of which seven villages (70%) were found Bacillus subtilis and three villages (30%) were found to be Bacillus megatherium. According to the laboratory experiment of phosphate solubilization, it was found that the fungi have more efficiency to solubilize the phosphate than bacteria. Hence there is need to develop the strain of fungi as phosphate fertilizer, also the application of the biofertilizer prepared by fungi should be helpful to reduce the salinity of soil by neutralization phenomenon, because these microorganisms release the acid in very minute quantity in phosphate Solubilization.

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	Fig. 1- Zone of Phosphate solublization by different fungi (1.1,and1.2) and bacteria (2.1 and 2.2) at 72hours
	Fig. 2- Appearance Bacterial isolates as Gram Positive under light microscope.
	Fig. 3- Efficiency of Phosphate solublization by fungi and bacteria
	Table 1- Biochemical characteristics of PSB (+ = Positive, - = Negative, A = Acid, d = Doubtful)