Study On Transformation Characteristics Of Inorganic Phosphorus In Phosphate Accumulating Fungi

Phosphorus is one of the essential elements for plant growth and development and it is also a key restrictive element of water eutrophication.Therefore,the biotransformation process of phosphorus is not only the focus of plant production,at the same time,it is also the research focus of environmental protection wastewater biological phosphorus removal,phosphorus recovery from sewage and agricultural non-point source pollution prevention and control.Phosphorus Accumulating Organisms?PAOs?are a kind of"special"microorganisms that can absorb phosphorus under aerobic condition and release phosphorus under anaerobic condition.In biological taxonomy,they belong to bacteria,actinomycetes and fungi.Such microorganisms are not only widely distributed in artificial ecosystems,such as sewage treatment systems in different regions and different biological phosphorus removal processes,but also widely distributed in water bodies,soils and other natural ecosystems and in the rhizosphere of plants.According to the definition and ecological distribution of phosphorous accumulating bacteria,we can speculate that phosphorus bioconversion in different ecosystems,especially in the alternating process of anaerobic and aerobic,will have an important effect on the solubility and bioavailability of phosphorus in the environment.Therefore,the discovery of the ability of phosphorus-accumulating bacteria to use different inorganic forms of phosphorus in the liquid phase system and the mechanism of phosphorus absorption and release in the solid phase system?soil?will theoretically enrich and improve the biogeochemical cycle of phosphorus.In practice,it is of great significance to continuously improve the stability of biological phosphorus removal in sewage treatment systems and the biological effectiveness of phosphorus in agricultural soils.In this study,Penicillium sp.18?abbreviated as Psp.18 strain?,a highly efficient polyphosphate-accumulating fungus isolated from the Microbiology Laboratory of Jilin Agricultural University,was used as the tested strain.The transformation of calcium phosphorus,aluminum phosphorus and other inorganic phosphorus in solid and liquid two-phase system and its influencing factors were studied preliminarily.The aim is to provide theoretical and data references for further understanding and regulation of the solubility and bioavailability of phosphorus in sewage treatment systems and farmland ecosystem soils.The results of the study in the liquid-phase system show that:1?Phosphorus-producing fungi Psp.18 were used as the only phosphorus source,namely calcium phosphate?Ca₃?PO₄?₂?,aluminum phosphate?AlPO₄?,iron phosphate?FePO₄?and ground phosphate rock,and they were shaken in NBRIP culture medium for 7days.Mycelial fresh weight of strain Psp.18 increased with the culturing time.,at the same time,the available phosphorus content in NBRIP medium showed an increasing trend,and the pH value gradually decreased with the increase of culture time.It was demonstrated that the strain can grow with the above-mentioned 4 kinds of inorganic phosphorus as the only phosphorus source.The results also show that the Phosphorus Phosphate not only can change the concentration of phosphorus in the solution through excessive absorption and release of phosphorus,but also can affect the phosphorus concentration of the liquid phase system by changing the solubility of insoluble phosphorus;its ability to utilize inorganic phosphorus is Ca₃?PO₄?₂>FePO₄>AlPO₄>ground phosphate rock.2?It was demonstrated that the strain can grow with the above-mentioned 4 kinds of inorganic phosphorus as the only phosphorus source.The results also show that the Phosphorus Phosphate not only can change the concentration of phosphorus in the solution through excessive absorption and release of phosphorus,but also can affect the phosphorus concentration of the liquid phase system by changing the solubility of insoluble phosphorus;its ability to utilize inorganic phosphorus is Ca₃?PO₄?₂>FePO₄>AlPO₄>ground phosphate rock.3?The results of the study on the best growth conditions and phosphorus uptake conditions of Psp.18 were as follows:the optimum growth temperature of strain Psp.18 was25°C,and the optimal phosphorus uptake temperature was 28°C;as the dissolved oxygen amount is 50mL,the growth and phosphorus uptake capacity of the strain Psp.18 is the bestThe strain Psp.18 is the best strain for glucose,and the organic acid is poor.In terms of phosphorus uptake capacity,organic acids are superior to sugars,and sodium acetate is the carbon source strain with the highest phosphorus uptake capacity.The use of different strains of nitrogen varies greatly,with ammonium salts being the best,organic nitrogen and nitrate being poor.When ammonium sulfate was used as the nitrogen source,both strain growth and phosphorus uptake capacity were the highest.The results of the study in the solid-phase system show that:4?In the cultivation experiment of black soil as the test soil:Phosphorus-accumulating Psp.18 strains have the effect of increasing the content of available phosphorus,Ca₂-P,Ca₈-P and Ca₁₀-P in black soil,no significant changes in other forms of inorganic phosphorus in black soil.Explains that Psp.18 can promote the transformation of insoluble Ca₁₀-P in black soil and increase the available phosphorus content in soil;but the conversion of Ca₂-P and slow-acting Ca₈-P is complex,which leads to the increase of the amount of phosphorus source to be further studied.5?The result of phosphorus conversion of soil Psp.18 to soil under different WFPS:the WFPS reach 40%and 60%of the strain can normally grow and multiply,the WFPS reach 80%,the microbial growth and reproduction ability in black soil is weak,and the available phosphorus in the soil increases;the WFPS reach 100%and 120%,the black soil microorganisms are in an anaerobic environment and no longer grow and multiply,at this time,the available phosphorus increases significantly,while the other inorganic forms of phosphorus do not change substantially.It shows that phosphorus-accumulating bacteria have the same phosphorus releasing mechanism under anaerobic conditions in soil.