• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.773-777
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• 2008

Phosphate solubilizing bacteria (PSB) were isolated from the rhizosphere of Chinese cabbage and screened on the basis of their solubilization of inorganic tricalcium phosphate in liquid cultures. Ten strains that had higher solubilization potential were selected, and they also produced indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and siderophores. The strains were identified to be members of Pseudomonas, by 16S rDNA sequence analysis. Seed bacterization with PSB strains increased the root elongation and biomass of Chinese cabbage in seedling culture, although they had no effect on phosphorus uptake of plants. The plant growth promotion by PSB in this study could be due to the production of phytohormones or mechanisms other than phosphate solubilization, since they had no effect on P nutrition.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.169-176
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• 2012

Among the major nutrients, phosphorus is by far the least mobile and available to plants in most soil conditions. A large portion of soluble inorganic phosphate applied to soil in the form of phosphate fertilizers is immobilized rapidly and becomes unavailable to plants. To improve the plant growth and yield and to minimize P loss from soils, the ability of a few soil microorganisms converting insoluble forms into soluble forms for phosphorus is an important trait in several plant growth-promoting microorganisms belonging to the genera Bacillus and Pseudomonas and the fungi belonging to the genera Penicillium and Aspergillus in managing soil phosphorus. The principal mechanism of solubilization of mineral phosphate by phosphate solubilizing bacteria (PSB) is the release of low molecular weight organic acids such as formic, acetic, propionic, lactic, glycolic, fumaric, and succinic acids and acidic phosphatases like phytase synthesized by soil microorganisms in soil. Hydroxyl and carboxyl groups from the organic acids can chelate the cations bound to phosphate, thereby converting it into soluble forms.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.197-202
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• 2003

Phosphorus is one of the major plant growth limiting nutrients, despite being abundant in soils in both inorganic and organic forms. Phosphobioinoculants in the form of microorganisms can help in increasing the availability of accumulated phosphates for plant growth by solubilization. Penicillium oxalicum CBPSTsa, isolated from paddy rhizosphere, was studied for its phosphate solubilization. The influence of various carbon sources like glucose, sucrose, mannitol and sorbitol and nitrogen sources like arginine, sodium nitrate, potassium nitrate, ammonium chloride and ammonium sulphate were evaluated using liquid media with tricalcium phosphate (Ca-P), ferric phosphate (Fe-P) and aluminium phosphate (Al-P). Maximum soluble phosphate of 824 mg/L was found in the amendment of sucrose-sodium nitrate from 5 g/L of Ca-P. Mannitol, sorbitol, and ariginine were poor in phosphate solubilization. While sucrose was better carbon source in solubilization of Ca-P and Al-P, glucose fared better in solubilization of Fe-P. Though all the nitrogen sources enhanced P solubilization, nitrates were better than ammonium In the amendments of ammonium chloride and ammonium sulphate, higher uptake of available phosphates by the fungus was found, and this resulted in depletion of available P in Fe-P amendment Phosphate solubilization was accompanied by acidification of the media, and the highest pH decrease was observed in glucose amendment Among the nitrogen sources, ammonium chloride favored greater pH decrease.

• 한국환경농학회:학술대회논문집
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• 2011.07a
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• pp.188-195
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• 2011

Red lateritic soils are typically low in total organic carbon (TOC) and available phosphorus (AP) content and continuous fertilization is required to obtain desired crop yield. In this experiment, cattle manure in three forms (air-dried, composted and vermicomposted) were applied to red lateritic soil to study their effect on TOC and AP content of soil and probable mechanism of P-solubilization as affected by these treatments were also studied. Vermicompost was the most effective to solubilize insoluble P in red lateritic soil (Alfisols) as compared to other organic amendments (air-dried cattle manure and compost). The highest SPA in vermicompost-treated soil attributed to the comparatively higher concentration of all the three SPA isozymes in these soils. The maximum P-solubilization in these soils might be attributed to the highest SPA and presence of several organic acids like citric, lactic and oxalic acids in vermicompost-treated soils. Since, vermicompost application also increased TOC, mineralizable N and exchangeable K content of soil, vermicompost could be considered as the most rational organic amendment to improve chemical properties of red lateritic soils.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.75-82
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• 2012

Swine wastewater was treated using a unique sequence of ion exchange membrane bed system (IEBR). Organic matter and nutrient in swine wastewater was pre-treated by electron beam irradiation. The optimal dose for solubilization of organic matter in swine wastewater ranged from 20 kGy to 75 kGy. The carbohydrates, proteins, and lipids were investigated as the solubilized organic fraction of swine wastewater and proteins and lipids mainly contained of the solubilized organic matter. The solubilization of organic matter in swine wastewater was affected by the combination effect of temperature and a dose. The average chemical oxygen demand (COD) removal efficiency under room temperature conditions was 67.1%, while that under psychrophilic conditions was 54.6%. For removal of ammonia, the removal efficiency decreased from 63.6% at $23^{\circ}C$ to 33.5% $16.8^{\circ}C$. On the other hand, the removal of phosphorus was not a function of temperature. Struvite was one of main mechanisms in anaerobic condition.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.428-434
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• 2012

A fungal strain, capable of solubilizing insoluble phosphate under diverse temperature, pH and salt conditions was isolated from Waste Mushroom bed of Agaricus bisporus in South Korea. Based on 18S rRNA analysis, the strain was identified as Aspergillus awamori bxq33110. The strain showed maximum phosphate solubilization in AYG medium (525 ${\mu}g\;mL^{-1}$) followed by NBRIP medium (515 ${\mu}g\;mL^{-1}$). The strain solubilized $Ca_3(PO_4)_2$ to a greater extent and rock phosphate and $FePO_4$ to a certain extent. However $AlPO_4$ solubilizing ability of the strain was found to be very low. Glucose at the rate of 2% ($561{\mu}g\;mL^{-1}$) was found be the best carbon source for Aspergillus awamori bxq33110 to solubilize maximum amount of phosphate. However, no significant difference ($P{\leq}0.05$) in phosphorus solubilization was found between 1% and 2% glucose concentrations. $(NH_4)_2SO_4$ was the best nitrogen source for Aspergillus awamori bxq33110 followed by $NH_4Cl$ and $NH_4NO_3$. At pH 7, temperature $30^{\circ}C$ and 5% salt concentration (674 ${\mu}g\;mL^{-1}$) were found to be the optimal conditions for insoluble phosphate solubilization. However, strain Aspergillus awamori bxq33110 was shown to have the ability to solublize phosphate under different stress conditions at $30-40^{\circ}C$ temperature, pH 7-10 and 0-10% salt concentrations indicating it's potential to be used as bio-inoculants in different environmental conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.66-73
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• 2012

Plant growth promoting traits like production of indoleacetic acid (IAA), ammonia, hydrogen cyanide (HCN), siderophore, and like the enzyme activities of catalase, ACC deaminase, cellulase, chitinase and protease were assayed in vitro for twenty one phosphorus solubilizing bacteria isolated from soil isolates. Except SPP-5 and SPP-15 strains, all the other isolated strains produced IAA in various amounts of 10 to $23{\mu}g\;ml^{-1}$. All strains showed positive response for ammonia production and ACC deaminase activity implying that they are capable of growing in a N-free basal medium. Catalase activity was found to be superior in SPP-2, SPP-7, SPP-12 and SPP-17 compared to the other strains tested. HCN production was detected by 15 strains and among them SPP-9, SPP-15, SAph-11, and SAph-24 were found to be strong HCN producers. Except the isolates SPP-10, SPP-12, SPP-13 and SPP-14, all the other isolates produced more than 80% siderophore units. None of the strains showed cellulose and chitinase activity. SAph-8, SAPh-11, SAPh-24 and SPP-15 strains showed 35.84, 50.33, 56.64 and 34.78 U/ml protease activities, respectively. SPP-1, SPP-2, SPP-3, SPP-11, SPP-17, SPP-18, SAph-11 and SAph-24 strains showed positive response for all the tested plant growth promotion traits except cell wall degrading enzyme activities. According to the results, all the tested phosphorus solubilizing isolates could exhibit more than three or four plant growth promoting traits, which may promote plant growth directly or indirectly or synergistically. Therefore, these phosphorus solubilizing strains could be employed as bio-inoculants for agriculture soils.

• Korean Journal of Agricultural Science
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• v.44 no.2
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• pp.196-210
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• 2017

The synergistic effect on phosphate solubilization of single- and co-inoculation of two phosphate solubilizing bacteria, Burkholderia cepacia (C1) and Alcaligenes aquatilis (H6), was assessed in liquid medium and maize plants. Co-inoculation of two strains was found to release the highest content of soluble phosphorus (309.66 ?g/mL) into the medium, followed by single inoculation of B. cepacia (305.49 ?g/mL) and A. aquatilis strain (282.38 ?g/mL). Based on a plant growth promotion bioassay, co-inoculated maize seedlings showed significant increases in shoot height (75%), shoot fresh weight (93.10%), shoot dry weight (84.99%), root maximum length (55.95%), root fresh weight (66.66%), root dry weight (275%), and maximum leaf length (81.53%), compared to the uninoculated control. In a field experiment, co-inoculated maize seedlings showed significant increases in cob length (136.92%), number of grain/cob (46.68%), and grain weight (67.46%) over control. In addition, single inoculation of maize seedlings also showed improved result over control. However, there was no significant difference between single inoculation of either bacterial strains and co-inoculation of these two bacterial strains in terms of phosphate solubilization index, phosphorous release, pH of the media, and plant growth parameters. Thus, single inoculation and co-inoculation of these bacteria could be used as biofertilizer for improving maize growth and yield.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.75-81
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• 1996

The dry matter (DM) disappearance and ruminal solubility of calcium (Ca), phosphorus (P), magnesium (Mg) and potassium (K) in eight Philippine forages were studied. The forages were: paragrass (Brachiaria mutica (Forsk.) Stapf), stargrass (Cynodon plectostachyum Pilger), napiergrass (Pennisetum purpureum Schumach), clopo (Calopogonium mucconoides Desv.), centrocema (Centrocema pubescens Benth.), gliricidia (Gliricidia sepium (Jacq.) Walp.), leucaena (Leucaena leucocephala (Lam.) de Wit.) and sesbania (Sesbania grandiflora (L.) Poir. Nylon bags with samples were incubated for 0, 3, 6, 12, 24, 48 and 72 h in rumen cannulated sheep. The 0-h bags were washed with deionized water. For the 0-h samples, 20.4, 17.2, 50.7, 52.2 and 80.1% of the DM, Ca, P, Mg and K was solubilized, respectively. At 3-h incubation period, DM disappearance was 10 percentage units higher than that of 0-h incubation whereas mineral disappearance increased by 43, 21, 30 and 13% for Ca, P, Mg and K, respectively. At 72-h incubation period, greater proportion of DM, Ca, especially in P, Mg and K was solubilized with a value of 73.8, 71.5, 85.6, 91.4 and 98.2%, respectively. The average particulate passage rate obtained in the present study was 1.9%/h where as the range of disappearance rates of various mineral elements were : 0.4 to 1.2%/h for Ca, 0.1 to 1.6%/h for P, 0.7 to 2%/h for Mg and 0.1 to 2%/h for K. The effective ruminal solubilization (ERS) of the macrominerals was calculated where particulate passage rate and disappearance rate of the various elements were included in the equation. The ERS of Ca, P, Mg and K was 50.0, 72.6, 83.9 and 94.5%, respectively. Species differences (p<0.05) on the various mineral solubilities were also observed. This study shows that ruminal solubility of macrominerals in selected Philippine forages is K > Mg > P > Ca.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.817-821
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• 2012

Soil samples collected from abounded mines of Boryeong area in South Korea were used in isolating bacterial strains and their capacity to solubilize inorganic phosphates and heavy metal tolerance were assessed in vitro. Three different inorganic phosphate sources (Ca phosphate, Fe phosphate, and Al phosphate) and four different heavy metals (Co, Cd, Pb and Zn) each with three concentrations ($100{\mu}g\;mL^{-1}$, $200{\mu}g\;mL^{-1}$, and $400{\mu}g\;mL^{-1}$) were used. The bacterial isolates PSB-1, PSB-2, PSB-3, and PSB-4 solubilized significantly higher amount of Ca phosphate during the first five days of incubation though subsequent drop in soluble phosphorus level in the medium was observed at the later stage (after 5 days) of the incubation. Solubilization of Ca phosphate and Fe phosphate was concomitant with the acidification of the culture medium compared to the control where it remained constant. Isolated strains could solubilize Fe phosphate to certain extent ($25-45{\mu}g\;mL^{-1}$) though solubilization of Al phosphate was found negligible. All the isolates were tolerant to heavy metals (Cd, Pb, and Zn) up to the concentration of $400{\mu}g\;mL^{-1}$ except PSB-1 and PSB-8, which were shown to be vulnerable to Co even at $100{\mu}g\;mL^{-1}$. Heavy metal tolerant strains should be further evaluated for plant growth promoting activities also under field conditions in order to assess their agricultural and environmental significance.