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Phosphate solubilization potential and phosphatase activity of rhizospheric Trichoderma spp.
Kapri, Anil;Tewari, Lakshmi;
Brazilian Journal of Microbiology , 2010, DOI: 10.1590/S1517-83822010005000001
Abstract: trichoderma sp., a well known biological control agent against several phytopathogens, was tested for its phosphate (p) solubilizing potential. fourteen strains of trichoderma sp. were isolated from the forest tree rhizospheres of pinus, deodar, bamboo, guava and oak on trichoderma selective medium. the isolates were tested for their in-vitro p-solubilizing potential using national botanical research institute phosphate (nbrip) broth containing tricalcium phosphate (tcp) as the sole p source, and compared with a standard culture of t. harzianum. all the cultures were found to solubilize tcp but with varying potential. the isolate drt-1 showed maximum amount of soluble phosphate (404.07 μg.ml-1), followed by the standard culture of t. harzianum (386.42 μg.ml-1) after 96 h of incubation at 30+10c. extra-cellular acid and alkaline phosphatases of the fungus were induced only in the presence of insoluble phosphorus source (tcp). high extra-cellular alkaline phosphatase activity was recorded for the isolate drt-1 (14.50 u.ml-1) followed by the standard culture (13.41 u.ml-1) at 72h. the cultures showed much lesser acid phosphatase activities. under glasshouse conditions, trichoderma sp. inoculation increased chickpea (cicer arietinum) growth parameters including shoot length, root length, fresh and dry weight of shoot as well as roots, in p-deficient soil containing only bound phosphate (tcp). shoot weight was increased by 23% and 33% by inoculation with the isolate drt-1 in the soil amended with 100 and 200 mg tcp kg-1 soil, respectively, after 60 d of sowing. the study explores high p-solubilizing potential of trichoderma sp., which can be exploited for the solubilization of fixed phosphates present in the soil, thereby enhancing soil fertility and plant growth.
Isolation of Phosphate-solubilizing Fungus and Its Application in Solubilization of Rock Phosphates
Wu Yingben,He Yuelin,Yin Hongmei,Chen Wei
Pakistan Journal of Biological Sciences , 2012,
Abstract: Microorganisms have been obtained to improve the agronomic value of Rock Phosphates (RPs), but the phosphorus solubilizing rate by these approaches is very slow. It is important to explore a high-efficient phosphate-solubilizing approach with a kind of microorganisms. This study aimed to isolate a high-efficient level of phosphate-solubilizing fungus from rhizosphere soil samples phosphate mines (Liuyang County, Hunan province, China) and apply it in solubilization of RPs. The experiments were carried out by the conventional methodology for morphological and biochemical fungus characterization and the analysis of 18s rRNA sequence. Then the effects of time, temperature, initial pH, phosphorus (P) sources, RPs concentration, shaking speed and silver ion on the content of soluble P released by this isolate were investigated. The results showed this isolate was identified as Galactomyces geotrichum P14 (P14) in GeneBank and the maximum amount of soluble P was 1252.13 mg L-1 within 40 h in a modified phosphate growth agar’s medium (without agar) where contained tricalcium phosphate (TCP) as sole phosphate source. At the same time, it could release phosphate and solubilize various rock phosphates. The isolated fungus can convert RPs from insoluble form into plant available form and therefore it hold great potential for biofertilizers to enhance soil fertility and promote plant growth.
Phosphate solubilization and synergism between P-solubilizing and arbuscular mycorrhizal fungi
Souchie, Edson Luiz;Azcón, Rosario;Barea, Jose Miguel;Saggin-Júnior, Orivaldo José;Silva, Eliane Maria Ribeiro da;
Pesquisa Agropecuária Brasileira , 2006, DOI: 10.1590/S0100-204X2006000900009
Abstract: the objective of this work was to evaluate the ability of several p-solubilizing fungi to solubilize aluminum phosphate and araxá apatite as well as the synergism between the p-solubilizing fungus, psf 7, and arbuscular mycorrhizal fungi to promote clover growth amended with aluminum phosphate. two experiments were carried out, the first under laboratory conditions and the second in a controlled environmental chamber. in the first experiment, psf 7, psf 9, psf 21 and psf 22 isolates plus control were incubated in liquid medium at 28oc for eight days. on the 2nd, 4th and 8th day of incubation, ph and soluble p were determined. in the second experiment, clover was sowed in plastic pots containing 300 g of sterilized substrate amended with aluminum phosphate, 3 g l-1, in presence and absence of psf 7 isolate and arbuscular mycorrhizal fungi. a completely randomized design, in factorial outline 2x2 (presence and absence of psf 7 and arbuscular mycorrhizal fungi) and five replicates were used. in the first experiment, higher p content was detected in the medium containing aluminum phosphate. psf 7 is the best fungi isolate which increases aluminum solubilization with major tolerance to al3+. clover growth was stimulated by presence of psf 7 and arbuscular mycorrhizal fungi. there is synergism between microorganisms utilized to improve plant nutrition.
Effect of immobilized phosphate solubilizing bacteria on wheat growth and phosphate uptake  [cached]
M Schoebitz,C Ceballos,L Ciamp
Journal of Soil Science and Plant Nutrition , 2013,
Abstract: A study was performed to investigate the efficiency of rhizobacteria on solubilization of rock phosphate and their assimilation by wheat plants in quartz sand potted experiments. Two phosphate solubilizing bacteria, P.fluorescens and Serratia sp. were encapsulated in sodium alginate and potato starch beads and selected to investigate the variation on pH values, the enzymatic activity of alkaline and acid phosphatase and phosphate solubilization in Pikovskaya liquid medium. A relation between pH diminution and P solubilization was found. P solubilization of 89 and 93 μg mL-1 was observed with immobilized phosphate solubilizing bacteria, which was significantly higher compared to autoclaved alginate-starch beads. Higher values around 64% in P uptake by wheat plants after 60 days of growth was observed with immobilized P.fluorescens+325 ppm of P. The results demonstrated that inoculation of the immobilized rhizobacteria is a promising option for inoculant carriers to increase P level in plants wheat and could be an innovative technique for application in agricultural industry.
ABUNDANCE AND OCCURRENCE OF PHOSPHATE SOLUBILIZING BACTERIA AND PHOSPHATASE IN SEDIMENT OF HOOGHLY ESTUARY, NORTH EAST COAST OF BAY OF BENGAL, INDIA  [cached]
T. K. De,T. K. Sarkar,M. De,T. K. Maity
Journal of Coastal Development , 2011,
Abstract: The abundance and occurrence of a special group of bacteria, capable of solubilizing or mobilizing insoluble phosphates were studied in estuarine environment, especially in sediments. The possible role of various factors of the sediments in maintaining the phosphate availability in the overlying water was described. The phosphatase activity was recorded in all samples irrespective of salinity variations. Total number of bacteria showed higher value in lower salinity. The total phosphate content in soil showed positive correlation with the phosphatase activity ( r = 0.890; P-Value = 0.000; n-=15). Clayey sediment contents more phosphate solubilizing bacteria and phosphatase than sandy sediment in a tropical estuarine region of River Hooghly.
Organic Acids Production and Phosphate Solubilization by Phosphate Solubilizing Microorganisms (PSM) Under in vitro Conditions  [PDF]
Maliha Rashid,Samina Khalil,Najma Ayub,Sadia Alam
Pakistan Journal of Biological Sciences , 2004,
Abstract: After screening a large number of phosphate solubilizing microorganisms (PSM) isolated from rice rhizosphere on the basis of solubilization index (SI) and pH drop ten best bacterial strains (10RB, 54RB, 57RB, 20RB, 21RB, 23RB, 22RB, 13RB, 20RB, 40RB) and three best fungal strains {(Aspergillus flavus(1RF), Penicillium canescens(4RF), A. niger (8RF)}were further analyzed for their acid production ability using HPLC technique. SI of 13 best isolates ranged from 2.16-6.23. SI and change of pH of these isolates showed abrupt changes during seven days of incubation in Pikovskayas agar and broth medium respectively. This drop of pH clearly indicated the production of organic acids. HPLC results confirmed that few PSM isolates produced gluconic, fumaric, succinic, acetic and some unknown organic acids in smaller concentrations while oxalic and citric acids in larger concentrations in their broth medium. Among bacterial strains 10RB produced largest amount of organic acids (2.4747 g-l) while among fungal isolates Aspergillus flavus produced greatest amount of acids (1.835 g-l) than the other two fungal strain. The concentration of glucose when analyzed during HPLC was found less in all the cultural samples as compared to the control (13 g-l) that was without any PSM culture. This shows that all the PSM strains utilized the carbon of glucose for the production of organic acids. The abilities of these efficient strains for phosphorus (P) solubilization and immobilization were also quantitatively investigated in Pikovskayas broth medium. The results showed that all the strains solubilized (0.04-0.1%) and immobilized (0.1-0.4%) P but fungi immobilized more P than bacteria. Correlation among all the parameters showed a positive(r = 0.2, P<0.1) correlation between the organic acid excretion and P solubilization and a negative correlation was found between pH and P solubilization (r =-0.4, P<0.1) and immobilization (r=-0.5, P<0.05).
ISOLATION AND BIOCHEMICAL CHARACTERIZATION OF PHOSPHATE SOLUBILIZING MICROBES
MAHANTESH P AND PATIL CS
International Journal of Microbiology Research , 2011,
Abstract: Phosphorus (P) is one of the essential macronutrients for plant growth and reproduction. Plants acquire Pfrom the soil solution as phosphate anions. However, phosphate anions are extremely reactive and may be immobilizedthrough precipitation with cations such as Ca2+, Mg2+, Fe3+ and Al3+, depending on the particular properties of thesoil and as a result, the phosphate is highly insoluble and unavailable to plants. Application of phosphate-solubilizingfungi (PSF) has been added as fertilizer to increase P uptake and plant growth. The improvement of soil fertility is oneof the most common strategies to increase agricultural production. Maintaining high levels of available nitrogen (N) andphosphorus (P), the two most limiting nutrients in soil, remains being a challenge.Major researches on biofertilizer have concentrated on understanding and improving N2 fixation. However, it is knownthat every aspect of the process of nodule formation is limited by the availability of P. Legumes like alfalfa and clovershow a high positive response to P supplementation (Gyaneshwar et al., 2002), but most of the supplemented Pbecome unavailable when its reacts with soil components.Many soil microorganisms are able to solubilize this unavailable P through their metabolic activities exudating organicacids, which directly dissolve the rock phosphate, or chelating calcium ions that release P to the solution. Production ofmicrobial metabolites results in a decrease in soil pH, which probably plays an important role in the solubilization (Abd-Alla, 1994).Phosphate solubilizing bacteria (PSB) were isolated from the area around Bidar region and screened on the basis oftheir solubilization of inorganic tricalcium phosphate in liquid cultures. Ten strains that had higher solubilization potentialwere selected, and they characterized
Diversity and phosphate solubilization by bacteria isolated from Laki Island coastal ecosystem
SRI WIDAWATI
Biodiversitas , 2011,
Abstract: Widawati S (2011) Diversity and phosphate solubilization by bacteria isolated from Laki Island coastal ecosystem. Biodiversitas 12: 17-21. Soil, water, sand, and plant rhizosphere samples collected from coastal ecosystem of Laki Island-Jakarta were screened for phosphate solubilizing bacteria (PSB). While the population was dependent on the cultivation media and the sample type, the highest bacterial population was observed in the rhizosphere of Ipomea aquatica. The PSB strains isolated from the sample registered 18.59 g-1L-1, 18.31 g-1L-1, and 5.68 g-1L-1 of calcium phosphate (Ca-P), Al-P and rock phosphate solubilization after 7-days. Phosphate solubilizing capacity was the highest in the Ca-P medium. Two strains, 13 and 14, registered highest Phosphomonoesterase activities (2.01 μgNP.g-1.h-1 and 1.85NP μg.g-1.h-1) were identified as Serattia marcescens, and Pseudomonas fluorescense, respectively. Both strains were isolated from the crops of Amaranthus hybridus and I. aquatica, respectively, which are commonly observed in coastal ecosystems. The presence of phosphate solubilizing microorganisms and their ability to solubilize various types of phosphate species are indicative of the important role of both species of bacteria in the biogeochemical cycle of phosphorus and the plant growth in coastal ecosystems.
Selection of Cocoa Tree (Theobroma cacao Linn) Endophytic Bacteria Solubilizing Tri-Calcium Phosphate, Isolated from Seedlings Grown on Soils of Six Producing Regions of Côte d’Ivoire  [PDF]
Adama Ouattara, Klotioloma Coulibaly, Ibrahim Konate, Boubacar Isma?l Kebe, Abiba Sanogo Tidou, Abdelkarim Filali-Maltouf
Advances in Microbiology (AiM) , 2019, DOI: 10.4236/aim.2019.99051
Abstract: Phosphorus (P) is an essential macronutrient for the growth and development of cocoa tree (Theobroma cacao Linn). Most of the soils used for cocoa farming in C?te d’Ivoire are low in phosphorus. But cocoa farmers generally have a widespread reluctance to invest in chemicals fertilizers due to high costs and environmental associated risk. Phosphate Solubilizing Bacteria (PSB) are kwon to play an important role in supply of phosphorous to plants in a sustainable manner in P deficient soils. The aim of this research was to screen the endophytic bacteria of cocoa nurseries able to solubilize tri-calcium phosphate. Seedlings of two varieties of cocoa (P7 and NA32) and seedlings of an all-comer, were grown on eighteen (18) samples soils collected in six producing regions of C?te d’Ivoire. A total of 218 endophytic bacteria were isolated and tested on the Pikovskaya’s agar medium, containing Ca3 (PO4) 2. The colonies with clear zone around the microbial growth were suspected as phosphate solubilizing bacteria. Out of 218 bacteria, 90 (41.28%) showed a clear zone around colonies after 7 days of incubation. The Phosphate Solubilization Index (PSI) ranged from 20% to 200%. Bacterial isolated from the soils of Duékoué locality showed the highest mean index of 137.67%. Five PSB (CEBSP5, CEBSP6, CEBSP7, CEBSP8, and CEBSP9) from Duékoué soils and two PSB (CEBSP12 and CEBSP13) from Soubré soils have a PSI ranged from 150% to 200%. Further study in greenhouse and in field condition will confirm the use of these PSB as biofertilizer to increase the available P content in soils, reduce environmental pollution and promote sustainable agriculture.
Phosphate Solubilization by Bacillus subtilis and Serratia marcescens Isolated from Tomato Plant Rhizosphere  [PDF]
Eman A. H. Mohamed, Azza G. Farag, Sahar A. Youssef
Journal of Environmental Protection (JEP) , 2018, DOI: 10.4236/jep.2018.93018
Abstract: Plants need phosphorus for many physiological activities in a form of phosphate anions. Three different bacterial strains (Bacillus subtilis PH, Serratia marcescens PH1, and Serratia marcescens PH2), recently isolated from tomato plant rhizosphere, have high phosphate solubilization index (SI from 2.8 to 3.2) on Pikovskaya agar medium (which contains calcium phosphate). Moreover, phosphate release from calcium in Pikovskaya broth over 5 days is increasing with cell growth for the different isolates. The most efficient phosphate solubilization case is the mixed culture of the 3 strains (OD475 is almost 1). On the other hand, pH values decreased dramatically with time due to organic acids secretion and the maximum acidification level is recoded for Serratia marcescens PH2 (pH = 1.94). Interestingly, the isolates are resistance to important pesticides (oxamyl, thiophanate methyl, and captan) that are commonly used in the sampling area. This resistance is very favorable and increases the persistence of the phosphate solubilizing bacteria in contaminated soils. The isolates are therefore plant symbionts and growth promoting agents.
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