Phosphorus Solubilizing Microorganisms Research Articles

Performance assessment of a Canna indica assisted vermifilter for synthetic dairy wastewater treatment

Abstract Two lab-scale vertical flow vermifilter were designed, one aided with Canna indica (MAVF) and the other without it (VF), but Eisenia fetida was inserted in both the systems. The experimental phase continued for ten weeks with a hydraulic loading rate of 0.65 m3 m−2 day−1. Results indicated that MAVF possess maximum organic and nitrogen degradation capacity during the treatment process and it was working steadily without sign of clogging, but vermifilter without macrophyte (VF) was clogged within the first few weeks of its operation. Removal efficiencies of BOD were 80.6% for MAVF and 71% for VF, while for COD it was 75.8% and 66.1%, respectively. TSS removal for MAVF and VF was found to be 84.8% and 73.8%, respectively, but TDS removal was insignificant in both the filters. Interlayer analysis presented that maximum organics and solids removed in the 1st layer or worm active zone. MAVF removed 42.6% TN, and effluent NH4+-N concentration in MAVF and VF were as low as 8.4 mg/L and 13.2 mg/L, respectively. However, TP concentration in effluent increased gradually may be due to the actions of phosphorus solubilizing microorganisms (PSM) and phosphatase enzymes secreted by earthworm. Growth characteristics of C. indica and E. fetida were also observed during the experimental period. Different physical and biochemical changes in soil due to plant and earthworm activity were analysed through FTIR, SEM and humic component analysis. The performance of MAVF was found to be superior to VF with high longevity.

Microbial Phosphorus Solubilization and Its Potential for Use in Sustainable Agriculture.

The use of excess conventional Phosphorus (P) fertilizers to improve agricultural productivity, in order to meet constantly increasing global food demand, potentially causes surface and ground water pollution, waterway eutrophication, soil fertility depletion, and accumulation of toxic elements such as high concentration of selenium (Se), arsenic (As) in the soil. Quite a number of soil microorganisms are capable of solubilizing/mineralizing insoluble soil phosphate to release soluble P and making it available to plants. These microorganisms improve the growth and yield of a wide variety of crops. Thus, inoculating seeds/crops/soil with Phosphate Solubilizing Microorganisms (PSM) is a promising strategy to improve world food production without causing any environmental hazard. Despite their great significance in soil fertility improvement, phosphorus-solubilizing microorganisms have yet to replace conventional chemical fertilizers in commercial agriculture. A better understanding of recent developments in PSM functional diversity, colonizing ability, mode of actions and judicious application should facilitate their use as reliable components of sustainable agricultural systems. In this review, we discussed various soil microorganisms that have the ability to solubilize phosphorus and hence have the potential to be used as bio fertilizers. The mechanisms of inorganic phosphate solubilization by PSM and the mechanisms of organic phosphorus mineralization are highlighted together with some factors that determine the success of this technology. Finally we provide some indications that the use of PSM will promote sustainable agriculture and conclude that this technology is ready for commercial exploitation in various regions worldwide.

Recycling Influence in Phosphorus Biossolubilization from Rock Phosphate Concentrate in Air-Lift Bioreactor

The nutrients availability for the plants is a determining factor for their development and growth. Phosphorus is an essential compound to plants, it is necessary to perform photosynthesis, respiration, gene transfer and reproduction. An alternative mechanism to the use of chemical fertilizers for increasing the cultures productivity on the soil phosphorus deficiency is the use of biotechnology by mainly biological processes occurring in the system soil/plant realized by phosphorus solubilizing microorganisms (PSM). Therefore, the objective of this study was to evaluate the phosphorus biossolubilization process from phosphate rock concentrate by Trichoderma harzianum in air-lift bioreactor employing reactive medium recycle. During 6 days was evaluated the phosphorus biossolubilization process by Trichoderma harzianum in air-lift reactor employing ascending air 0.5 vvm (volumetric flow per minute) and reaction medium recycle containing phosphate rock concentrated (5 g/L). Phosphorus biossolubilization by Trichoderma harzianum in air-lift reactor only with upward aeration (0.5 vvm) showed maximum solubilization equal to 212.19 ppm (27.23%), followed by 98,18% of glucose consumption and total acid concentration equal to 1.25 µmol/ml (0.5 µmol/ml of lactic acid, and 0.73 µmol/ml of acetic acid) in the fifth process day at 28 ± 0,5°C. By employing reaction medium recycle flow of 200 mL/min in air-lift reactor with aeration of 0.5 vvm at 28 ± 0.5°C, initial cell inoculum concentration equal to 3.5 ± 0.5 g/L and 5 g/L of phosphate rock concentrate and glucose was obtained on the third day of process 244.9 ppm (31.42% solubilization) of soluble phosphorus. By increasing the volumetric flow rate of recycle to 400 ml/min maintaining the same conditions, in the fourth day was reached 216.1 ppm (27.73% solubilization) of soluble phosphorus and 8.2 µmol/ml of organic acids (lactic and acetic). Comparing the results achieved between the three phosphorus biossolubilization process from phosphate rock concentrate in air-lift reactor by Trichoderma harzianum was observed that by employing recycle of reactive medium at 200 mL/min associated with compressed air flow at 0.5 vvm was obtained for a shorter period (3 days) a higher concentration of phosphorus soluble in a liquid medium (244.9 ppm). Indicative of the positive influence of the reactive medium recycle in the phosphorus availability process by Trichoderma harizianum from the production of organic acids using glucose as substrate.

Effect of integrated application of phosphorus and phosphate solubilizing microorganisms on root colonization, productivity and seed quality of Cucurbita pepo L.

Effect of integrated application of phosphorus and phosphate solubilizing microorganisms on root colonization, productivity and seed quality of Cucurbita pepo L.

Enrichment and Isolation of Phosphorus Solubilizing Bacteria

The aim of this study was to enrich phosphorus solubilizing microorganisms from high-phosphorus iron ores, apatite ores and phosphogypsum waste. Phosphorus solubilizing microorganisms can be utilized in dephosphorization of high-phosphorus iron ores and in phosphorus leaching from fluorapatite ores. Low grade fluorapatite ore (3.6% P, pH 6.8), fluorapatite concentrate (13% P, pH 8.3), phosphogypsum waste (0.7% P, pH 2.3), iron ore 1 (0.19% P, pH 7.6) and iron ore 2 (0.18% P, pH 7.6) were used as potential sources of phosphorus solubilizing microorganisms. The samples were cultured in NBRIP media at pH 5 and 8 with either glucose or sucrose as a carbon source, and in modified 9K media at pH 1.5 and 2.5 for 3 weeks. Phosphorus solubilizing bacteria were enriched only from the fluorapatite concentrate at the pH of 8. The four obtained heterotrophic isolates were identified by 16S rRNA gene sequencing, and were shown to be closest related to Burkholderia fungorum. These results indicate that the diversity of culturable phosphorus solubilizing bacteria present in apatite and iron ores is relatively low. The isolated Burkholderia strain showed phosphorus solubilizing potential.

Phosphate-solubilizing microbes and their occurrence in the rhizospheres of Piper betel in Karnataka, India

Low phosphate solubility is one of the most important factors limiting the plant growth in Indian soils. Many microorganisms can enhance phosphate solubility, but little is known about the magnitude of their phosphorus-solubilizing ability. The native populations of phosphate-solubilizing bacteria and fungi were studied in different rhizospheric soil samples obtained from betel vine plants (Piper betel L.) in order to compare the results. The present study focuses on the phosphate-solubilizing capacity of bacteria and fungi in rhizospheric soil samples obtained from betel vine plants, revealing the dominance of Aspergillus species (26.1 mm) as major phosphate solubilizers, along with Bacillus subtilis (46.6 mm) among the bacteria that utilize tricalcium phosphate, potassium dihydrogen phosphate, and rock phosphate as phosphate sources. The other phosphorus-solubilizing microorganisms were Bacillus species, Streptomyces, Aspergillus fumigatus, Nocardia, actinomycetes, and certain yeasts. The presence of high numbers of phosphate-solubilizing bacterium Bacillus subtilis (3 × 10^6 cfu g^{-1}) and fungus Aspergillus niger (3 × 10^5 cfu g^{-1}) in the rhizospheric zones of Piper betel plants explains how the plants obtain their nutrient requirements. The identity of Aspergillus species and Bacillus with the maximum zone was confirmed using molecular sequencing with 16s rDNA. The sequence data were aligned and analyzed to identify the bacteria along with their closest neighbors.

Effect of rhizobia, mycorrhizal fungi and phosphate-solubilizing microorganisms in the rhizosphere of native plants used to recover an iron ore area in Brazil

The iron-ore deposits in Minas Gerais state are concentrated in an area named Ferruginosous Quadrilateral, in which the dominant vegetation belongs to the Cerrado biome (savanna type, called campo rupestre or rupestrian field). This vegetation occurs in altitudes higher than 1000 m and is one of the most endangered biomes of the world. This study aimed to restore an area of rupestrian field used to keep iron-ore products, in which vegetation had been cut and thus resilience did not occur, worsening the low fertility of the fragile soil. Therefore, a revegetation model was proposed using two native species, Centrosema coriaceum (Leguminosae) and Tibouchina multiflora (Melastomataceae), inoculated with selected strains of arbuscular mycorrhizal fungi (AMF) and/or a rhizobium strain. After 48 months of plantation, the plant growth, survival index, physical and chemical soil properties, leaf nitrogen (N) and phosphorous (P), and P soil were evaluated. Inoculated plants benefited in all the analyzed aspects. While T. multiflora presented increased P content in leaves and soil rhizosphere only in inoculated plants, C. coriaceum showed the highest P content in both leaves and soil independently of inoculation. Although the inoculated plants presented more intense root colonization (AMF), the same mycorrhizal species were found in both inoculated and non-inoculated plants of C. coriaceum and T. multiflora. However, species of the Gigasporaceae family were favored in the C. coriaceum rhizosphere, as compared with T. multiflora. In addition, C. coriaceum was able to select in its rhizosphere a rhizobia strain efficient in P solubilization and a large and efficient population of phosphorus solubilizing microorganisms (PSM), preferentially composed of fungi. Through the similarity of their Internal Transcribed Spacer (ITS) sequences, the PSM fungi were identified as Fusarium oxysporum and Aspergillus fischeri using the BLAST database. The data presented suggest that C. coriaceum showed a strong rhizosphere effect in favor of a tripartite action of rhizobia, fungi and AMF populations as strategies to solubilize soil phosphate for survival and plant growth in the rupestrian field. Therefore, the inoculation of these microorganisms is desirable for mine recover.

Nutrient recycling potential in rice–vegetable cropping sequences under in situ residue management at mid-altitude subtropical Meghalaya

Low native soil nitrogen (N) and very low phosphorus (P) coupled with apathy of farmers towards use of fertilizer are the major constraints limiting rice productivity in the North Eastern Hill (NEH) Region of India. Field experiment was undertaken in narrow valley wetland during Kharif and pre-Kharif (rainy) seasons of 2003, 2004, and 2005, respectively, at Umiam (950 m MSL), Meghalaya to evaluate the nutrient recycling and production potential of rice (Oryza sativa L.)—vegetables cropping sequences under low input in situ residue management under rainfed conditions. After rice, five vegetable crops, viz. tomato (Lycopersicon esculentum Mill), potato (Solanum tuberosum L.), frenchbean (Phaseolus vulgaris), cabbage (Brassica oleracea L. var. capitata), and carrot (Daucas carota L.) were grown during pre-kharif season on temporary raised and sunken beds. Minimum tillage was given to both rice and vegetables. No external input including fertilizer, organic manure, pesticides, etc. were applied to either crops. Only the economic parts of the crops were harvested and the rest of the biomass of the entire crop and weed residues were chopped and incorporated into the soil. Among the five cropping sequences, rice–tomato gave the highest rice equivalent yield (214.40 q/ha), followed by rice–carrot (206.4 q/ha). Highest net return (rupees [Rs.] 66,635 ha−1) was recorded in rice–carrot, closely followed by rice–tomato (Rs. 66,139 ha−1). Rice–cabbage and rice–frenchbean were found to be on a par with each other in terms of yield and income. The highest amount of NPK recycling was recorded for the rice–potato sequence. Weed biomass production in the different sequences ranged from 37.5 q/ha for rice–tomato to as high as 50.6 q/ha in the case of rice–fallow. Soil fertility in terms of available NPK status was found to be stable in all the crop sequences except rice–cabbage, where fertility status declined slightly. The soil biological properties such as population of Rhizobium, bacteria, phosphorus-solubilizing microorganisms, and earthworm activity were all found to be remarkably higher in the experimental field compared to other adjacent plots that are managed inorganically. It was concluded that vegetables such as tomato, carrot, potato, etc. could be profitably grown after rice without the addition of fertilizer and manure, if residues are managed effectively under temporary raised beds without deteriorating soil fertility.

Phosphorus Solubilizing Microorganisms in the Rhizosphere of Local Rice Varieties Grown without Fertilizer on Acid Sulfate Soils

Local farmers who living in South Kalimantan (Banjarese farmers) apply almost none of phosphatic (P) fertilizers to grow local rice varieties. This practice has been adopted for many years. We have investigated the mechanisms involved in P availability for the crop. This study focuses on identifying microorganisms involved in solubilizing insoluble P. The study was conducted in Balandean District, South Kalimantan, Indonesia. The soil was classified as acid sulfate soil. Three out of 8 rice varieties grown were selected for net P balance in the soil-plant system and the microbial studies. We found that the P uptakes by the rice crop was much higher than the sum of P released from soil, water and soil microbial biomass P. It was also observed that these soils harboured bacteria and fungi that have the capability of dissolving aluminium phosphate (AIPO4) and tricalcium phosphate [Ca3(PO4)2]. Based on the area of clear zone on plates, it seem that there were variations of ability in dissolving Al-P or Ca-P. DNA sequence analysis shown that Burkholderia sp. was the common P solubilizing bacterium found in the rhizosphere of rice varieties Siam Unus, Siam Ubi and Siam Puntal. The presence of other bacteria was specific for each rice variety grown.

Effect of levels and sources of phosphorus and phosphate solubilizing microorganisms on growth, yield and quality of sugarcane

Field investigations were carried out at Regional Research Station, Visweswaraya Canal Farm, Mandya (Karnataka) to study the effect of soil inoculation of phosphate solubilizing organisms (PSM) in conjunction with levels and sources of P on growth, yield and quality of sugarcane-Plant and ratoon during 1995 to 1998. The bacterial cultures viz.,Agrobacterium radiobacter andBacillus megaterium in plant crop and the fungusAspergillus awamori in ratoon crop are efficient P solubilizers. Their inoculation with soluble P source viz., SSP and in combination with pressmud (PM) ascentuates their effect as P solubilizers. Enhanced uptake and higher tissue indices of P besides N and K were indicative of better nutrient use efficiency and their positive influence on various growth and yield parameters. Improvement in cane yields (8 to 10%), economy in fertilizer P (25%) are suggestive of cost effectiveness and higher net returns due to their inoculation.

Field evaluation of dual inoculation of alfalfa with Sinorhizobium meliloti and Penicillium bilaii

Field experiments were conducted at five sites to evaluate the effects of dual inoculation of alfalfa (Medicago sativa L.) with Sinorhizobium meliloti and Penicillium bilaii, a phosphorus-solubilizing fungus, on the yield and quality of alfalfa hay. Dual inoculation with S. meliloti strain NRG-34 and P. bilaii strain PB-50 increased nodule number and occupancy, but resulted in only small increases in hay yield and total nitrogen and phosphorus concentrations of hay compared with inoculation with S. meliloti alone. There was little response of alfalfa to phosphorus fertilizer at the sites, and this may partly explain the small effects of dual inoculation of the two microorganisms. There were no significant differences in nodulation, hay yield or hay nutrient concentrations between alfalfa inoculated with separate NRG-34 and PB-50 inoculant products and that inoculated with a co-cultured inoculant. This similarity in response supports use of a single effective delivery system for the two different rhizosphere microorganisms, which is of great practical relevance as producers are more likely to adopt technology that requires a single inoculation procedure than one requiring two separate inoculation procedures at planting time. Key words: Co-cultured inoculant, Medicago sativa, phosphorus-solubilizing microorganisms, Penicillium bilaii, Sinorhizobium meliloti

Integrated nutrient mangement in rainfed hybrid cotton

A field experiment was conducted at Regional Research Station, Bhawanipatna, Kalahandi, Orissa in the Kharif seasons of 1997 and 1998. The treatment N, P and K @ 100, 50 and 50 kg har along with Azatobacter and Phosphorus Solublizing Micro-organisma @ 5 kg ha' each, ZnSO, 25 kg ha' and FYM @10 t ha produced the highest seed cotton yield of 2728 kg ha' and that was on par (2695 kg ha') with the above treatment minus ZnSO, 25 kg ha¹. The crop height, bolls / plant and the boll weight recorded for both the above treatments were also on par with each other for both the years. However, the net return per rupee invested was the highest (Rs. 2.43) for the treatment N, P and K @ 100, 50 and 50 kg ha along with Azatobacter and Phosphorus Soublilizing Micro-organisms @ 5 kg ha-1 each and FYM @10 1 hat followed by Rs. 2.26 for the treatment N. P and K @ 100, 50 and 50 kg ha-1 along with. Azatobacter and Phosphorus Solubilizing Micro-organisms @ 5 kg/ha-1 each, ZnSO, 25 kg ha-1 and FYM @10 t ha-1.