Showing papers on "Phosphate solubilizing bacteria published in 2007"

Isolation and characterization of mineral phosphate-solubilizing bacteria naturally colonizing a limonitic crust in the south-eastern Venezuelan region

Abstract: With the aim to explore the possible role of mineral phosphate-solubilizing bacteria (PSB) in phosphorus (P) cycling in iron-rich, acidic soils, we conducted a survey of PSB naturally colonizing a limonitic crust in the south-east region of Venezuela (Bolivar State). A total of 130 heterotrophic bacterial isolates showing different degrees of mineral tri-calcium phosphate (Ca 3 (PO 4 ) 2 )-solubilizing activities were isolated from NBRIP plates. In contrast, no isolates showing iron phosphate (FePO 4 )- or aluminum phosphate (AlPO 4 )-solubilizing activities were detected by this experimental approach. The 10 best Ca 3 (PO 4 ) 2 -solubilizers were selected for further characterization. These isolates were shown to belong to the genera Burkholderia , Serratia , Ralstonia and Pantoea by partial sequencing analysis of their respective 16S rRNA genes. All the PSB isolates were able to mediate almost complete solubilization of Ca 3 (PO 4 ) 2 in liquid cultures; in contrast, the PSB isolates were less effective when solubilizing FePO 4 . Two groups of PSB isolates were clearly differentiated on the basis of their Ca 3 (PO 4 ) 2 solubilization kinetics. Acidification of culture supernatants seemed to be the main mechanism for P solubilization. Indeed, gluconic acid was shown to be present in the supernatant of five isolates. Furthermore, detection of genes involved in the production of this organic acid was possible in three isolates by means of a PCR protocol.

Phosphate-solubilization activity of bacterial strains in soil and their effect on soybean growth under greenhouse conditions

Abstract: The efficiency of 13 phosphate-solubilizing bacteria (PSB; four Burkholderia sp., five Enterobacter sp., and four Bradyrhizobium sp.) was assessed in a soil plate assay by evaluating soil phosphorus (P) availability. A commercial argentine strain, Pseudomonasfluorescens, was used for comparing solubilizing activity. Burkholderia sp. PER2F, Enterobacter sp. PER3G, and Bradyrhizobium sp. PER2H strains solubilized the largest quantities of P in the soil plate assay after 60 days as compared with the other strains, including the commercial one. The effect of PSB inoculation on growth and nutrient uptake of soybean plants was also studied under greenhouse conditions. Plants inoculated with Burkholderia sp. PER2F had the highest aerial height and showed an appropriate N/P ratio. However, none of the PSB increased P uptake by plants. This suggests that PSB inoculation does not necessarily improve P nutrition in soybean, nor was there any relationship between P availability in the soil plate assay and P content in the soybean shoot in the greenhouse. We concluded that the selection of efficient PSB strains as possible inoculation tools for P-deficient soils should focus on the integral interpretation of soil assays, greenhouse experiments, and field trials.

Co-inoculation of nitrogen-fixing and phosphate-solubilizing bacteria to promote growth, yield and nutrient uptake in chickpea

Abstract: A total of 32 bacterial isolates including Mesorhizobium (N=10), Azotobacter (N=12) and phosphate-solubilizing bacteria (N=10) were isolated and tested for siderophore, HCN, ammonia, indole acetic acid production and phosphate solubilization in vitro . The bacterial cultures were positive for siderophore, HCN and ammonia. Among the isolates, M. ciceri RC3 and A. chrococcum A4 displayed 35 and 14 μg ml −1 of IAA, respectively, whereas Bacillus produced 19 ( Bacillus PSB1) and 17 μg ml −1 ( Bacillus PSB10) of IAA in Luria Bertani broth. The diameter of the P solubilization zone varied between 4 ( Bacillus PSB1) and 5 mm ( Bacillus PSB10) and a considerable amount of tricalcium phosphate (7 and 8 μg ml −1 by Bacillus PSB1 and Bacillus PSB10, respectively) was released in liquid medium, with a concomitant drop in pH. The effects of N 2 -fixing and PS bacteria on the growth, chlorophyll content, seed yield, grain protein and N uptake of chickpea plants in field trials varied considerably between the treatments...

Sustaining productivity of wheat–soybean cropping system through integrated nutrient management practices on the Vertisols of central India

Abstract: Wheat–soybean is one of the most dominant cropping systems on the Vertisols of central India. Cultivation of durum wheat in winter season (November to April) has a considerable potential due to congenial climate, while soybean in rainy season (June to October) has witnessed a phenomenal growth in the last two decades in the region. Beside including a legume (soybean) in sequence with a cereal crop (wheat), combined use of available organic sources along with chemical fertilizers may prove beneficial for long-term productivity and sustainability of the system. A long-term experiment was conducted during 1995–2000 on the fine-textured Vertisols at Indore, India to study the effect of combined use of farmyard manure (FYM), poultry manure, vermicompost and biofertilizers (Azotobacter + phosphate solubilizing bacteria) with 0.5 and 1.0 NPK (120 kg N + 26.2 kg P + 33.3 kg K ha−1) on wheat, and residual effect on following soybean. Grain yield of aestivum wheat in the initial 2 years and durum wheat in the later 3 years was significantly increased with 0.5 NPK + poultry manure at 2.5 t ha−1 or FYM at 10 t ha−1 compared with 0.5 NPK alone, and was on par with 1.0 NPK. However, the highest productivity was obtained when these organic sources were applied along with 1.0 NPK. Quality parameters of durum wheat viz protein content, hectolitre weight and sedimentation value showed improvement, and yellow berry content was significantly lower with combined use of NPK + organic sources compared with NPK alone and control. Soybean did not show much response to residual effect of nutrient management treatments applied to wheat. Wheat gave higher profit than soybean, particularly in the later years due to lower grain yields and market price of soybean. However, the superiority of FYM as well as poultry manure along with 1.0 NPK was evident on the overall profitability of the system. Various soil fertility parameters including chemical and biological properties showed conspicuous improvement over the initial status under the treatments of FYM and poultry manure. Sustainability yield index was maximum under 1.0 NPK, followed by 1.0 NPK + poultry manure or FYM. It was concluded that application of available organic sources, particularly FYM and poultry manure along with full recommended dose of NPK fertilizers to wheat was essential for improving productivity, grain quality, profitability, soil health and sustainability of wheat–soybean system.

First International Meeting on Microbial Phosphate Solubilization

Abstract: Contents Preface Taxonomy of rhizobia: An Overview: A. Willems Genetics of phosphate solubilization and its potential application for improving plant growth-promoting bacteria: H. Rodriguez, R. Fraga, T. Gonzalez & Y. Bashan Biodiversity of populations of phosphate solubilizing rhizobia that nodulates chickpea in different Spanish soils: R. Rivas, A. Peix, P. F. Mateos, M.E. Trujillo, E. Martinez-Molina & E. Velasquez Phosphate solubilization activity of rhizobia native to Iranian soils: H. A. Alikhani, N. Saleh-Rastin & H. Antoun Differential effects of coinoculations with Pseudomonas jessenii PS06 (a phosphate-solubilizing bacterium) and Mesorhizobium ciceri C-2/2 strains on the growth and seed yield of chickpea under greenhouse and field conditions: A. Valverde, A. Burgos, T. Fiscella, R. Rivas, E. Velazquez, C. Rodriguez-Barrueco, E. Cervantes, M. Chamber and J. M. Igual Effect of Tilemsi phosphate rock solubilizing microorganisms on phosphorus-uptake and yield of field grown wheat in Mali: B. A. Hamadoun & H. Antoun Screening for PGPR to improve growth of Cistus ladanifer seedlings for reforestation of degraded mediterranean ecosystems: B. Ramos, T. Pereyra de la Iglesia, A. Probanza, J.A. Lucas Garcia, M. Mejias & F.J.Gutierrez Manero Phosphate-solubilizing microorganisms isolated from rhizospheric and bulk soils of colonizer plants at an abandoned rock phosphate mine: I. Reyes, A. Valery & Z. Valduz Microbial solubilization of rock phosphate on media containing agro-industrial wastes and effect of the resulting products on plant growth and P uptake N. Vassilev, M. Vassileva, A. Medina & R. Azcon Making microorganisms mobilize soil phosphorous: A. Richardson Future trends in research on microbial phosphate solubilization: one hundred years of insolubility: A. H. Goldstein Molecular methods for biodiversity analysis of phosphate solubilizing bacteria (PSB): A.Peix , E. Velazquez & E. Martinez-Molina Taxonomy of phosphate solubilizing bacteria: P. Kampfer Taxonomy of filamentous fungi and yeasts that solubilizes phosphate: E. Velazquez & M. E. Trujillo Phosphate solubilizing microorganisms: effect of Carbon, Nitrogen, and Phosphorus sources: E. Nahas Efficacy of organic acid secreting bacteria in solubilization of rock phosphate in acidic alfisols: S. Srivastava, M. T. Kausalya, G. Archana, O. P. Rupela & G. Naresh-Kumar Solubilization of iron and aluminum phosphates in the soil by the fungus Aspergillus niger: C. B. Barroso & E. Nahas Fertilizers, food and environment: J. M. Igual & C. Rodriguez-Barrueco Phosphate Solubilizing Microorganisms vs. Phosphate Mobilizing Microorganisms: What separates a phenotype from a trait?: A. H. Goldstein & P.U. Krishnaraj Challenges in commercializing a phosphate solubilizing microorganism: Penicillium bilaiae, a case history: M. Leggett, J. Cross, G. Hnatowich, & G. Holloway Interactive effects of phosphate-solubilizing bacteria and mycorrhizal fungi at increasing plant P availability and their evaluation by using isotopic techniques: J. M. Barea, M. Toro & R. Azcon Distribution pattern and role of phosphate solubilizing bacteria in the enhancement of fertilizer value of rock phosphate in aquaculture ponds: state-of-the-art: B.B. Jana Construction of a vector for stable chromosomal integration of the phoc gene in plant growth- promoting bacteria: R. Fraga-Vidal, H. Rodriguez Mesa & T. Gonzalez -Diaz de Villegas Microorganisms with capacity for phosphate solubilization in Dao red wine (Portugal): L. R. Silva, R. Rivas, A. M. Pinto, P. F. Mateos, E. Martinez-Molina & E. Velasquez Phosphate solubilizing microorganisms in the rhizosphere of native plants from tropical savannas: an adaptive strategy to acid soils?: M. Toro Effects of solarization on phosphorus and on other chemical constituents of soil: A.F.M.A. Pinto, L.R. Silva, E. Velazquez, & A.Cesar Tricalcium-phosphate solubilizing efficiency of rhizosphere bacteria depending on the P-nutritional status of the host plant: A. Deubel, A. Gransee & W. Merbach Phosphate Solubilizing Microorganisms in the rhizosphere of Pinus pinaster and in the mycosphere of associated Lactarius deliciosus: B. Ramos, J. Barriuso-Maicas, J.A. Lucas Garcia, T. Pereyra de la Iglesia, A. Daza & F.J.Gutierrez Manero Characterization of a strain of Pseudomonas fluorescens that solubilizes phosphates in vitro and produces high antibiotic activity against several microorganisms: M. E. Trujillo, E. Velazquez, S. Miguelez, M. S. Jimenez, P. F. Mateos & E. Martinez-Molina Phosphate solubilizing Bacteria Isolated from the inside of Glomus clarum spores from Cuba: L. Mirabal-Alonso & E. Ortega-Delgado Polyphasic characterization of phosphate-solubilizing bacteria isolated from rhizospheric soil of the north-eastern region of Portugal: A. Valverde, J. M. Igual & E. Cervantes Effects of plant community composition on total soil microbiota and on phosphate-solubilizing bacteria of ex-arable lands: I. Santa-Regina, A. Peix, T. Diaz, C. Rodriguez-Barrueco & E. Velasquez Population dynamics of p-solubilizers in the rhizosphere of major weed species from a tropical delta soil: S. Seshadri & C. Lakshminarasimhan Malic acid mediated aluminum phosphate solubilization by Penicillium oxalicum CBPS-3F-Tsa isolated from Korean paddy rhizosphere soil: R. Gadagi & T. Sa Growth promotion of rice by phosphate solubilizing bioinoculants in a Himalayan location: P. Trivedi, B. Kumar, A. Pandey & L. M. S. Palni Evaluation of the effect of a dual inoculum of phosphate-solubilizing bacteria and Azotobacter chroococcum, in crops of creole potato (papa "criolla"), "yema de huevo" variety (Solanum phureja): G. Faccini, S. Garzon, M. Martinez & A. Varela Effect of inoculation with a strain of Pseudomonas fragi in the growth and phosphorous content of strawberry plants: L. Martin, E. Velazquez, R. Rivas, P. F. Mateos, E. Martinez-Molina, C. Rodriguez-Barrueco & A. Peix Effects of phosphate solubilizing bacteria during the rooting period of sugar cane (Saccharum officinarum), Venezuela 5171 variety, on the grower's oasis substrate: M. Martinez & A. Martinez Phosphate Solubilizing Bacteria Isolated from the Rhizosphere Soil and its Growth Promotion on Black Pepper (Piper nigrum. L) Cuttings: K. Ramachandran, V. Srinivasan, S. Hamza & M. Anandaraj Effect of phosphorous solubilizing bacteria on the rhizobia-legume symbiosis: S. B. Rosas, M. Rovera, J. A. Andres & N. S. Correa Defense response in bean roots is not affected by low-phosphate nutrition: L. Alvarez-Manrique, A. Richards & E. Soriano Solubilization of phosphate by a strain of Rhizobium leguminosarum bv. trifolii isolated from Phaseolus vulgaris in El Chaco Arido soil (Argentina): A. Abril, J. L. Zurdo-Pineiro, A. Peix, R. Rivas & E. Velasquez Effect of phosphate solubilizing bacteria on role of Rhizobium on nodulation by soybean: D.L.Wasule, S .R. Wadyalkar & A.N.Buldeo Phaseolus lunatus is nodulated by a phosphate solubilizing strain of Sinorhizobium meliloti in a Peruvian soil: E. Ormeno, R. Torres, J. Mayo, R. Rivas, A. Peix, E. Velazquez, D. Zuniga Phosphate solubilizing rhizobia originating from Medicago, Melilotus and Trigonella grown in a Spanish soil: M. Villar-Igea, E. Velazquez, R. Rivas, A. Willems, P. van Berkum, M. E. Trujillo, P. F. Mateos, M. Gillis & E. Martinez-Molina Effect of phosphorous on nodulation in nitrogen fixation by Phaseolus vulgaris: M. Olivera, N. Tejera, C. Iribarne, A. Ocana & C. Lluch Phaseolus vulgaris is nodulated by phosphate solubilizing strains from a new genomic group of Sinorhizobium meliloti in Canary Island soils: J. L. Zurdo-Pineiro, A. Peix, R. Rivas, M. Leon-Barrios, A. Garrido-Martin, R. Perez-Galdona, P. F. Mateos, E. Martinez-Molina & E. Velasquez Role of arbuscular mycorrhizal fungi in the uptake of phosphorus by micropropagated blackberry (Rubus fruticosus var. brazos) plants: Y. Carreon- Abud & E. Soriano- Bello Effect of plant species and mycorrhizal inoculation on soil phosphate-solubilizing microorganisms rhizosphere in semi-arid brazil: growth promotion effect of rhizospheric phosphate-solubilizing microorganisms on Eucalyptus camaldulensis: M. R. Scotti, N. Sa, I. Marriel, L. C. Carvalhais, P. P. Pinto, S. R. Matias, E. J. Correa, N. Freitas, M. A. Sugai, R. V. Passos The interactive effects of arbuscular mycorrhizal fungi and rhizobacteria on the growth and nutrients uptake of sorghum in acid soil: J. Widada, D. I. Damarjaya, and S. Kabirun Fertilizer potential of phosphorus recovered from wastewater treatments: L. E. de-Bashan & Y. Bashan Microalgae growth-promoting bacteria as "helpers" for microalgae: a novel approach for removing ammonium and phosphorus from municipal wastewater: L. E. de-Bashan, J. P. Hernandez & Y. Bashan Immobilization of mercury in soils of Venezuela using phospho-gypsum and sulphate-reducing bacteria: E. Adams, A. Garcia-Sanchez, F. Santos, E. Velazquez & M. Adams-Melendez Soil phosphate solubilizing microorganisms and cellulolitic population as biological indicators of iron mined land rehabilitation: M.R.M. Scotti, N.H. Sa, S.R. Matias, R. Passos, J. R. Stehmann & J.P. Lemos-Filho Effect of certain phosphate solubilizing bacteria on root-knot nematode disease of mungbean: M. R. Khan Two strains isolated from tumours of Prunus persica are able to solubilize phosphate in vitro: J. L. Palomo, P. Garcia-Benavides, P. F. Mateos, E. Martinez-Molina & E. Velasquez Inorganic phosphate solubilization by two insect pathogenic Bacillus sp.: S. Seshadri, S. Ignacimuthu, M. Vadivelu & C. Lakshminarasimhan Effect of certain fungal and bacterial phosphate solubilizing microorganisms on the fusarial wilt of tomato: M. R. Khan & S. M. Khan

Isolation and Identification of Potential Phosphate Solubilizing Bacteria from the Rhizoplane of Oryza sativa L. cv. BR29 of Bangladesh

Abstract: A total of 30 bacteria were isolated from the rhizoplane of rice cv. BR29 cultivated in Mymensingh, Bangladesh and from the seedlings obtained from surface-sterilized seeds of BR29. Upon screening, 6 isolates showed varying levels of phosphate solubilizing activity in both agar plate and broth assays using National Botanical Research Institute's phosphate medium. The bacterial isolates were identified based on their phenotypic and 16S rRNA genes sequencing data as Acinetobacter sp. BR-12, Klebsiella sp. BR-15, Acinetobacter sp. BR-25, Enterobacter sp. BR-26, Microbacterium sp. BRS-1 and Pseudomonas sp. BRS-2. The BR-25 exhibited highest phosphate solubilizing activity followed by BR-15. They grew rapidly in the liquid medium at pH 5 and 7 but almost no growth occurred at pH 3. The pH value of the culture medium was decreased with bacterial growth suggesting that they might secrete organic acids to solubilize insoluble phosphorus. Scanning electron microscope analysis of two-week-old rice seedlings germinated from seeds previously inoculated with BR-25 and BR-15 revealed dense colonization at the root surfaces presumably using fimbriae on the bacterial cells.

Influence of compost, microorganisms and npk fertilizer upon growth, chemical composition and essential oil production of rosmarinus officinalis l.

Abstract: The performance of compost and microorganisms was compared with standard, commercial rates of NPK fertilizers with respect to the growth, chemical composition and essential oil production of Rosmarinus officinalis L. In two successive seasons, plants treated by a mixture of compost and microorganisms showed a significant increase in vegetative growth, total N, P and carbohydrate content and essential oil production. The findings clearly indicate that compost and microorganisms could replace conventional NPK fertilizers in the cultivation of rosemary, and consequently minimize environmental pollution by these compounds.

Phosphate solubilizing bacteria isolated from the rhizosphere soil and its growth promotion on black pepper (Piper nigrum L.) cuttings

Abstract: Bacterial isolates from the rhizosphere soil and root cuttings of bush black pepper (Piper nigrum L.) (pepper raised by laterals) exhibiting high phosphate solubilizing ability in-vitro is described in this paper. Microbial phosphorus solubilization (MPS) trait was analyzed by determining the P solubilization efficiency E (E = Diameter of bacterial growth/Diameter of clearing zone×100). The highest P solubilization efficiency was demonstrated by the isolate PB-21 followed by the isolate PB-16: which was identified as Pseudomonas sp. All isolates under study released inorganic phosphate from tricalcium phosphate (TCP) indicating the potential of these strains to release soluble inorganic phosphates from fixed phosphate sources for plant uptake. The isolate PIAR6-2 was able to solubilize 20.01% of P and also fix atmospheric nitrogen, which was later identified as the nitrogen fixing Azospirillum sp. Greenhouse trials using two systems; viz; Soil:Terracare (composted coir pith) and Sand:Soil:FYM with three experimental sets such as rock phosphate (RP as an external P source), PSB isolate in combination with VAM and PSB isolate alone, all against their respective control sets showed very clearly the growth promoting activity of phosphate solubilizing bacteria. Field studies were also carried out using these isolates and some promising results were obtained. Further studies are required to analyze these strains to confirm its plant growth promoting properties. The in-vitro analyses and greenhouse studies of these bacteria reflect their potentiality as efficient P solubilizer in black pepper growing soils.

Biocontrol of a chickpea root-rot disease complex with phosphate-solubilizing microorganisms

Abstract: SUMMARY The effects on chickpea (Cicer arietinum) of the phosphate-solubilizing microorganisms Aspergillus awamori, Pseudomonas aeruginosa (isolate Pa28) and Glomus intraradices in terms of growth, and content of chlorophyll, nitrogen, phosphorus and potassium and on the root-rot disease complex of chickpea caused by Meloidogyne incognita and Macrophomina phaseolina were evaluated. Application of these phosphate-solubilizing microorganisms alone and in combination increased plant growth, pod number, and chlorophyll, nitrogen, phosphorus and potassium contents, and reduced galling, nematode multiplication and root-rot index of chickpea. Pseudomonas aeruginosa reduced galling and nematode multiplication the most followed by A. awamori and G. intraradices. Combined inoculation of these microorganisms caused the greatest increase in plant growth and reduced the root-rot index more than individual inoculations. Pathogens adversely effected root colonization by G. intraradices. However, root colonization and root nodulation were increased when co-inoculated with P. aeruginosa and A. awamori whether in the presence or absence of pathogens.

Solubilization of phosphate by a strain of Rhizobium leguminosarum bv. trifolii isolated from Phaseolus vulgaris in El Chaco Arido soil (Argentina)

Abstract: Several strains were isolated from Phaseolus vulgaris plants growing in a soil from El Chaco Arido (Argentina). Although most of strains nodulating Phaseolus are not P-solubilizers in plates containing bicalcium phosphate, we tested the isolates and among them, one strain (ARPV02) was able to solubilize phosphate in plates. This strain showed a high ability to nodulate and to fix nitrogen in common bean. Sequencing of 16S rRNA was performed in the strain ARPV02, showing a 100% similarity with the former type strain of Rhizobium trifolii ATCC14480. This strain is currently considered as a biovar of species Rhizobium leguminosarum together biovars viceae and phaseoli. These biovars have been defined basing on their ability to nodulate a concrete group of legumes. In this way, the strains belonging to biovar trifolii nodulate Trifolium. However, in previous studies we have shown that in Spanish soils strains from this biovar nodulate Phaseolus. Besides the solubilization of phosphate, the strain ARPV02 isolated in this study is able to movilize phosphorous to common bean plants.

The interactive effects of arbuscular mycorrhizal fungi and rhizobacteria on the growth and nutrients uptake of sorghum in acid soil

Abstract: The inoculation effects of arbuscular mycorrhizal fungi (AMF) or/and rhizobacteria, (phosphate-solubilizing bacteria, PSB; N2-fixing bacteria, NFB; and siderophore-producing bacteria, SPB) on the growth and nutrients uptake of sorghum (Sorghum bicolor) were studied in acid and low availability phosphate soil. The microbial inocula consisted of the AMFs Glomus manihotis and Entrophospora colombiana, PSB Pseudomonas sp., NFB Azospirillum lipoferum, and SPB fluorescent pseudomonad. The inoculation of either AMF or each rhizobacterium improved the plant dry weight and nutrients uptake such as N, P, Fe, and Zn. Dual inoculation of AMF and each rhizobacterium yielded the higher of plant dry weight and nutrients uptake compared to the single inoculation. Dual inoculation of AMF and PSB, AMF and NFB, AMF and SPB increased plant dry weight by 112, 64, and 60 times higher compared to the uninoculated plant, respectively. The rhizobacteria also improved plant colonization by AMF. These results indicated that the interaction of AMF and the selected rhizobacteria has a potential to be developed as biofertilizers in acid soil.

Survival of bio-inoculants on fungicides-treated seeds of wheat, pea and chickpea and subsequent effect on chickpea yield

Abstract: Survival of Mesorhizobium ciceri (SP4) and Azotobacter chroococcum (CBD-15 and M4) was tested on chickpea (Cicer arietinum) seeds treated with fungicides bavistin [methyl N-(1H-benzimidazol-2yl) carbamate] and thiram (tetramethyl-thiuram disulfide), whereas survival of phosphate solubilizing bacteria (PSB), Pseudomonas striata (27) and Bacillus polymyxa (H5) was examined on two cultivars (Arkel and BV) of pea (Pisum sativum) seeds treated with thiram. Viability of Azotobacter chroococcum (W5) was also examined on wheat (Triticum aestivum) seeds treated with bavistin, captan (cis-N-trichloromethyl thio-4 cyclohexane-1, 2-dicarboximide) and thiram under laboratory conditions using standard dilution and the plate count technique. All the tested strains of diazotrophs and PSB showed decline in their viable population on prolonged contact with fungicides. However, PSB showed variation in their viable population even with the cultivar. BV cultivar of pea seeds showed better recovery of viable P. striata (10.75 ...

Distribution pattern and role of phosphate solubilizing bacteria in the enhancement of fertilizer value of rock phosphate in aquaculture ponds: state-of-the-art

Abstract: Phosphorus, though required in small quantities, has often been implicated as the most limiting element controlling biological productivity in natural waters. As a result, aquaculture ponds demand for frequent application of phosphate fertilizer for enhanced fish production. It is estimated that about 10% of the fertilizer applied caused increase in soluble phosphate in the water phase, which is absorbed by the phytoplankton within few minutes of fertilizer application, whereas the rest is rapidly precipitated and settled at the bottom and converted into insoluble compounds. Thus, the pond bottom acts as a sink of phosphorus in fertilized ponds, whereas a source of P in unfertilized ponds. Increasingly high cost of chemical phosphate fertilizers has been the main stimulus for searching alternative cheap, effective and dependable source of phosphorus from natural sources for pond fertilization. Rock phosphate is trade name of mineral phosphates, which denotes the product obtained from mining and subsequent metallurgical processing of phosphorus containing ores. India has a vast reserve of 126.90 million tones of rock phosphate. Though the available form of phosphorus obtainable from rock phosphate is very little, it contains essential nutrients like calcium, magnesium, zinc, molybdenum, silica, organic carbon and potash, which are useful in biological production. It has proved to be an important phosphate fertilizer for agriculture soils under acidic conditions. A major problem encountered in the direct application of rock phosphate in fish ponds is that it is sparingly soluble in water. The association of tricalcium phosphate and calcium fluoride forming a mineral fluorapatite had made it more resistant to weathering. In the biogeochemical cycle of phosphorus, a mixed population of microbes is essential to promote enzymatic degradation of naturally occurring organic phosphorus compounds. Extracellular products of the microbial community such as enzymes and chelating agents (organic acids) have substantial effect, respectively on phosphorus mobilization from organic P esters and inorganic salts. Phosphatases are stated to promote the degradation of complex phosphorus compounds into orthophosphate, which can be readily utilized by phytoplankton. Alkaline phosphatase can catalize the liberation of orthophosphate from organic P compounds and inorganic pyrophosphate and tripolyphosphate. Synthesis of external alkaline phosphatases is often repressed by high concentrations of phosphate and depressed at low phosphate concentration. This enables to use phosphatase activity as a good indicator of the degree of nutrient regeneration in surface sediments. Solubilization of insoluble inorganic phosphate by bacteria is of considerable importance in the anthropogenically-managed system. A large number of phosphate solubilizing microorganisms such as bacteria, fungi, and cyanobacteria occurring in water and sediments of fish ponds are capable of assimilating insoluble inorganic phosphate like hydroxyapatite, tricalcium phosphate, and rock phosphate and make a large portion soluble by the production of organic and inorganic acids. It is suggested that solubilization of rock phosphate during the process of its composting with organic substances is accelerated by the liberation of organic acids in the first step and proliferation of phosphate solubilizing microorganisms at a later stage. It is reported that amongst the microbes, Bacillus is the most effective one in respect of phosphate solubilization and phosphates production. Invertebrates can contribute to the mineralization of dissolved and particulate compounds in the sediment and their burrowing activity can affect several exchange processes by increasing the mixing of the sediment surface. A number of bottom grazing fishes are also able to increase the fertilizer value of rock phosphate through their bioturbation effects in bottom sediments. This has been clearly demonstrated in experimental studies. Exogenous introduction of phosphate solubilizing bacteria is of considerable interest in solubilization of rock phosphate in fish culture ponds because of extremely low natural microbial solubilization of rock phosphate in fish ponds. Exogenous introduction of phosphate solubilizing bacteria with compost resulted in the highest concentrations of different species of phosphate in water or sediments among all treatments. This was attributable to the combined effects of the phosphate solubilizing bacteria population of both exogenous and compost origin with short generation time. The present paper reviews the state-of-the-art of various approaches for using rock phosphate as direct source of phosphate fertilizer and the dynamics of phosphate solubilizing bacteria and bacteria induced solubilization of rock phosphate in the fish culture ponds of India.

Effect of phosphate solubilizing bacteria on role of Rhizobium on nodulation by soybean

Abstract: Studies were conducted in laboratory to find out the most effective phosphate solubilizer. The phosphate solubilizing microorganisms were isolated from rhizosphere on Pikovskaya’s solid medium by serial dilution. Most efficient phosphate solubilizers were identified on Pikovskaya’s solid medium by measuring clear zone around the colony and measurement of pH. The result indicates that Aspergillus awamori among fungi and Pseudomonas striata among bacteria produce large sized clear zones around the colony i.e. (0.5 cm) and change the pH of medium from initial 5.8 to 2.5 and 4.5, respectively. To determine the effect of phosphate solubilizing bacteria on role of Rhizobium on nodulation, nodule dry weight, dry matter of plant, 1000 seed weight and yield a field experiment was conducted with eight treatments i.e. Rhizobium + PSB, Rhizobium, PSB, Full fertilizer dose, Half fertilizer dose, Full fertilizer dose + Rhizobium + PSB, Half fertilizer dose + Rhizobium + PSB and Control. Rhizobium + PSB yielded maximum number of nodules (67.13) and nodule dry weight (107.73 mg) Rhizobium alone showed maximum production of dry matter (3.63 gm). Full fertilizer dose + Rhizobium + PSB gave highest 1000 seed weight (109.92 gm). Half fertilizer dose + Rhizobium + PSB gave highest yield (10.67 q/ha) which was equivalent to yield recorded with Full fertilizer dose + Rhizobium + PSB (10.66 q/ha) and Rhizobium + PSB (10.63 q/ha).

The use of 32 P isotopic dilution techniques to evaluate the interactive effects of phosphate-solubilizing bacteria and mycorrhizal fungi at increasing plant P availability

Abstract: Isotopic (32P) dilution approaches have been used to evaluate the extent at which inoculated phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal (AM) fungi improve plant use of soil P sources of low bioavailability, either endogenous or added as rock phosphate (RP) This paper firstly examines the conceptual background, the main achievements and the state of the art on the related topics Then, a model own experiment is described and discussed to offer a comprehensive view on the effects and mechanisms involved, and to propose the appropriate methodological approaches Measurements of the specific activity (32P/31P) of P in plants grown in 32P-labelled soil, and the subsequent calculations of the amount of plant P derived from either the bio-available (isotopically labelled) soil sources or from the added RP, allow to conclude that the dually (AM + PSB)-inoculated plants were able to use otherwise unavailable P sources, resulting in an improvement of plant P acquisition The proposed mechanism is that the inoculated PSB actually release phosphate ions (31P) from sparingly soluble phosphates, ions which are taken up by the external AM mycelium to be transferred to the plant

Effect of co-inoculants (bradyrhizobia and phosphate solubilizing bacteria) liquid on soybean under rice based cropping system in the mekong delta

Abstract: Three experiments were carried out on three different provinces of the Mekong Delta viz., An Giang, Can Tho and Dong Thap to study the effect of bradyrhizobia (Bradyrhizobium japonicum) and phosphate solubilizing bacteria (Pseudomonas spp.) in liquid inoculant (s) on soybean. The treatments composed of different combination level of inorganic nitrogen fertilizer levels (namely 20, 40, 60 kg N/ha) and liquid inoculant (s) (Bradyrhizobium japonicum and/or Pseudomonas spp.) in comparison to conventional farmers' fertilizer level (80 N - 60 P 2O5 - 30 K 2O kg/ha). The results showed that application of bradyrhizobia (Bradyrhizobium japonicum) and phosphate solubilizing bacteria (Pseudomonas spp.) liquid inoculants on soybean seed before sowing plus 20 kg N/ha enhanced the nodule number, fresh weight, dry weight of nodules, yield components and grain yield in comparison to conventional farmers' fertilizer level. Moreover, this cultural practice not only saved 40 - 60 kg N and 60 kg P2O5 kg/ha and also obtained higher economic efficiency in term of Marginal benefit Cost Ratio (MBCR) to an extent level of 43.98%.

Taxonomy of phosphate solublizing bacteria

Abstract: Although phosphate solubilizing capabilities seem to be widespread within bacterial taxa, it is surprising, that the description of phosphate solubilizing bacteria is restricted to relatively few bacterial genera. Among the bacteria, strains belonging to the genus Rhizobium and related organisms have been investigated most extensively until now. In addition, several other organisms belonging to taxonomically different and phylogenetic largely unrelated genera (e.g. Bacillus, Paenibacillus, Escherichia, Enterobacter, Rahnella, Pseudomonas, Burkholderia and some others) have been studied for their potential to solubilize phosphate. This report gives a short overview on the taxonomy of these genera and some reommendations for identification of unknown organisms with phosphate solubilizing potential in the light of microbial diversity in soil and the current species “definition” in bacteriology.

Effect of certain phosphate-solubilizing bacteria on root-knot nematode disease of mungbean

Abstract: Bacillus subtilis, B. polymyxa, Pseudomonas fluorescens and P. stutzeri were cultured on nutrient broth and were applied on the seeds of mungbean at 5 mL/kg of seeds along with the rhizobium. The seeds were sown in microplots (3×1.5 m) where nematode suspension (1500 second stage juveniles of Meloidogyne incognita/kg soil) had already been added or not added. Three microplots which were randomly distributed in the field were maintained for each treatment. In the plots without nematodes, plants showed better growth with significantly improved yield, especially with P. stutzeri. Root-nodulation was significantly increased due to the treatments of P. stutzeri or B. polymyxa compared to uninoculated control. Inoculation with the nematode caused severe galling on roots and decreased the yield of mungbean by 23.8%. Application with P. fluorescens or B. subtilis suppressed the gall formation, reproduction and soil population of M. incognita. The nematicidal effect of the PSMs was considerably less than the fenamiphos treatment (at 2 g/kg seed). Rhizosphere population of all PSMs tested was significantly increased over time irrespective of nematode presence or absence. Application of P. fluorescens suppressed the nematode pathogenesis and increased the yield of mungbean by 30.9% that was greater than the nematicide treatment (16.7%).

Effect of inoculation with a strain of Pseudomonas fragi in the growth and phosphorous content of strawberry plants.

Abstract: Within genus Pseudomonas, several species are able to solubilize phosphate in plates and some of these species are also able to mobilize phosphorous to plants. In this work we isolated a strain, SAPA2, from the rhizosphere of barley plants growing in a soil from Northern Spain. This strain was able to solubilize phosphates in plates forming great halos of solubilization in 24 h. Moreover, this strain retained its ability to solubilize phosphate after five culture passes. The 16S rRNA sequence of this strain showed a similarity of 99.9% with that of Pseudomonas fragi. The inoculation of strawberry plants with this strain was carried out in growth chamber applying 10 ml of a suspension containing 108 UFC/ml to each plant. According to the results obtained, the plants inoculated with this strain growing in a soil amended with insoluble phosphate had a phosphorous content significantly higher than uninoculated plants growing in soil with or without insoluble phosphates. Therefore, the strain SAPA2 promotes phosphorous mobilization to strawberry plants. Therefore, the inoculation of plants with suitable phosphate solubilizing bacteria can increase the crop yield and allows a better exploitation of natural soil resources.

Evaluation of the effect of a dual inoculum of phosphate-solubilizing bacteria and Azotobacter chroococcum, in crops of creole potato (papa “criolla”), “yema de huevo” variety (Solanum phureja)

Abstract: Four isolates of PSB (Pseudomonas cepacia, Xanthomona maltophilia, Enterobacter cloacae and Acidovorans delafieldii, formerly called P. delafieldii) and four strains of Azotobacter chroococcum, isolated in a previous work were chosen. They did not show antagonism among themselves, by means of in vitro tests made on GISA medium (PSB-Azotobacter modified medium). A dual inoculum was made with the 8 isolates in 4.6 L of sterile GISA broth, which was under continuous air flow. This dual inoculum was taken to a field sample where seeds of “criolla” potato, yema de huevo variety (Solanum phureja) were cultivated. After120 days from inoculation, statistical analyses showed that as for stem height, dry weight of the root, number of tubers and soil available phosphorus, there were significant differences among the various treatments. As for all other variables, there were no observable differences among them. With the a posteriori test of Tukey, it was possible to determine that with chemical fertilization — with or without dual inoculum, — the stem height, the fresh weight of plants, fresh weight of leaves and tubers, the results were significantly greater than with the other treatments. The dry weight of roots, and the soil available N, showed better results with the inoculation of 50% of the inoculum plus 50% of chemical fertilizer. The number of tubers showed better results with 100% of fertilizer. A dual inoculum of PSB and Azotobacter chroococcum like the one used in this research, will maintain production (ton/ha) of “criolla” potato, Yema de Huevo variety (Solanum phureja), at a level matching that of crops with 100% NPK fertilization only, and at the same time, will contribute to the reduction of costs (in nearly 7.4%), a fact that represents favorable implications at both, economical and environmental levels.

Effects of phosphate-solubilizing bacteria during the rooting period of sugar cane (Saccharum officinarum), Venezuela 51–71 variety, on the grower’s oasis substrate

Abstract: One hundred samples of rhizosphere taken from 16 crop lands located in the Tolima, Cundinamarca, and Casanare departments were assessed to isolate solubilizing bacteria (PSB) populations. PSB constituted 20% of the total isolated population. Two isolates identified as Xanthomonas maltophilia and Enterobacter cloacae, were selected for their ability to form solubilization halos within a Pikovskaya medium with Ca3(PO4)2. In a greenhouse assay, buds of sugar cane, variety Venezuela 51–71, were planted and fertilized with Fosforita Huila, in the Grower’s Oasis rooting medium. Then, an inoculation with the two selected microorganisms was performed on treatments that showed no significant differences in phosphate uptake at 90 days, as compared with the control. However, there were significant differences in plant growth, as the stem length under the phosphate treatment and the mixture of the two bacteria was of 32 cm, while such length was of 17 cm under the positive control. Similarly, stem length with the phosphate treatment and E. cloacae was of 9 cm, as compared with 5 cm with the positive control. As for root growth, an increase of 2.57 times was observed, as related to the positive control’s dry weight. Root length was increased 0.73 times, being similar to that of the KNO3 control.

Effect of Bioinoculants and Bioregulators on Yield and Nutrient Uptake by Fenugreek ( Trigonella foenum-graecum L.)

Abstract: A field experiments were conducted during rabi season of 2001–02 and 2002–03 to study the effect of bioinoculants and bioregulators on yield, nutrient content and uptake by fenugreek crop. The study revealed that the dual inoculation of seeds with Rhizobium + phosphate solubilizing bacteria (Bacillus megatherium var. phosphaticum) resulted in significant increase in yield, N and P content and NPK uptake by seed and straw over other treatments. However, inoculation with Rhizobium or PSB alone were found at par. Foliar application of bioregulators viz., GA3, NAA and brassinosteriod had significant effect on yield, nutrient content and uptake by the crop. However, 20 ppm NAA spray produced mean maximum of 17.60 and 47.05 qha−1 seed and straw yield, respectively. N and P content and uptake by fenugreek crop were the highest under 20 ppm NAA treatment which was closely followed by 10 ppm NAA treatment.

Influence of integrated nutrient management on vegetative growth parameters of marigold (Tagetes erecta L.).

Abstract: Different chemical and biofertilizers were tried at different levels to study the effect of integrated nutrient management on vegetative growth of marigold. Regarding the growth parameters viz. height of the plant, number and length of primary branches and stem diameter increased subsequently at all the growth stages of the crop and at 90 DAT, significantly maximum height of the plant (119.60 cm), number of primary branches per plant (13.26), length of the primary branches (36.50cm) and stem diameter ( 2.47cm) were recorded in the treatment receiving 70% RDF + Azospirillum 5 kg ha -1 + PSB 5 kg ha -1 . Also this treatment showed maximum fresh weight of shoots (232.66 g) and roots (94.33 g) and total dry matter weight (100.35 g). However, the standard with recommended dose of fertilizers was found to be the second best treatment. See end of article for authors’ affiliations Correspondence to :

Interactive Effect of Phosphate Solubilizing Bacteria and Bradyrhizobium japonicum on Growth, Nodule Indices and Some Nutrient Uptake of Soybean

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Polyphasic characterization of phosphate-solubilizing bacteria isolated from rhizospheric soil of the north-eastern region of Portugal

Abstract: Phosphate-solubilizing microorganisms are often used as plant growth promoters. In the frame of a project focused on the isolation of endosymbionts and ectorhizospheric bacteria associated with Phaseolus vulgaris plants growing in a mountain soil at the north-east of Portugal, we obtained six bacterial strains with high phosphate-solubilizing capability, as demonstrated by the formation of ‘halos’ when plated in YED medium supplemented with tricalcium-phosphate. These bacterial strains were characterized by a polyphasic approach using both phenotypic (API 20 NE) and molecular assays (RAPD, with M13 primer, TP-RAPD, and 16S rDNA sequencing). TP-RAPD yielded an identical band patterns in the six strains indicating that they belong to the same bacterial species. The 16S rRNA sequence analysis of a group-representative strain (P4-22) revealed a sequence similarity value of 99.27% with Pseudomonas jessenii. Moreover, the RAPD fingerprints of these six strains did not show differences, indicating that they form a highly homogenous group. This high homogeneity could be a consequence of the recurring agronomical practices used in this region from the antiquity that include organic fertilization and monoculture of Phaseolus vulgaris.

Evaluación de la acción de un bioinoculante sobre un cultivo de crisantemo (chrysanthemun morifolium var. yoko ono) en período de enraizamiento

Abstract: The objective of these research was to evaluate the impact of a non-commercial bioinoculum produced in a crop plantation located in the savannah of Bogota, and used like organic fertilizer in the phases of rooting and production beds, different microbial groups were isolated from Microagro isolated themselves, and indoleacetic acid (IAA) production was verified on these isolations, by means of Salkowski colorimetric reaction. It was observed that the phosphate solubilizing bacteria (PSB) Burkholderia cepacia concentrated the greater production of IAA in an individual inoculum at the fourth day of incubation, having obtained 14,823 μg/ml, in comparison to the positive control, Azotobacter vinelandii ATCC 12518, which produced 18,332 μg/ml and Salmonella enteriditis ATCC 13221 wich produced 0.384 μg/ml of IAA. On the other hand, it was observed that under a mixed inoculum the production of IAA was 5,826 μg/ml at the fifth day of incubation. Also, the action of Microagro was evaluated in the process of rooting of chrysanthemum (Chrysanthemum morifolium to var. yoko ono), for this we settled down 3 treatments: husk and compost (treatment 1), husk and Microagro (treatment 2) and husk, compost and Microagro (treatment 3); and a control. Above this was evaluated height, fresh weight, dry weight, dry radicular weight, rate of mortality and symptomatic incidence of damping off and white mould on chrysanthemum cuttings. It was observed that the microbial action influenced in a fundamental way the increase of the fresh weight of chrysanthemum cuttings (3,5 g) (p < 0,001), the treatment with husk and compost increased in greater amount the height (18,77 cm) (p < 0,001) and radicular dry weight (0,113 g) (p < 0,001). At the end of the rooting test, an important characteristic was observed, marked by the minor percentages presented in the symptomatic incidence of damping off and white mould, and the mortality rate in the three treatments where the organic substratum were used to enrich the chrysanthemum cuttings (< 0,1%).