Producing Biofertilizer With Spent Mushroom Substrate Using Co-inoculation Of Various Of Phosphate-solubilizing, Potassium Solubilizing And Nitrogen Fixing Bacteria

The purpose of this paper is to screen the microbial strains which have the abilityof phosphate-soluilizing, potassium-solubilizing and nitrogen-fixing. Spent mushroomsubstrate biofertilizer was produced by co-inoculation of screened strains tested foron the crops growth was researched by pot experiment. It will provide a strategy toreuse the spent mushroom substrate.Four phosphate-solubilzing microorganisms, four potassium-solubilizingmicroorganisms and four N2-fixing microorganisms were isolated from saline-alkalisoil. The capacity of solubilizing phosphate, potassium and nitrogen fixation wereanalyzed. And then the resistance of these strains to high temperature, highconcentration of ammonium and salt, and the value of was studied, too. The16SrDNA sequence of fourteen selected strains were analyzed by the method ofmolecular identification. Then with the combination of morphological taxonomy, P5,P7, P8and P9were preliminary identified as Pseudomonas putida, Bacillusmegaterium, Pseudomonas fluoresens and Bacillus subtilis, respectively. K5, K8, K9and K10were preliminary identified as Actinomycete, Bacillus amyloliquefaciens,Bacillus subtisli, and Bacillus licheniformis, respectively. N3was identified asMicrococcus, N5, N7and N9were identified as Bacillus licheniformis.The P8was cultivated in the optimal medium to study the relationships organicacid and P solubilization, pH.708.263mg/L total organic acids can be produced after3d, meanwhile, the content of soluble phosphate reached412.85mg/L and pH reducedto5.2, which proved the production of organic acids to be an mechanism forsolubilizing P.Spent mushroom substrate (SMS) as the carrier were conversion to biofertilizersusing co-inoculation of these twelve screened strains and three preservative strains(phosphate-solubilzing microorganisms FL7, potassium-solubilizing microorganismsK3and N2-fixing microorganisms N1) in the laboratory. The content ofphosphate-solubilizing, potassium-solubilizing and total nitrogen as the index, theoptimal conditions of factors were30°C, pH7,70%initial water content,200rpm ofrotate speed,400g/L of loading capacity,60mesh of particle diameter,0.2%of nitrogen source and inorganic salt in the single factor experiment. Meanwhile, thecontent of soluble phosphate, soluble potassium and N2-fixing was positivecorrelation with the quantity of microorganisms. The content ofphosphate-solubilizing, potassium-solubilizing and total nitrogen as the index,optimization of medium compost and fermentation conditions were studied with the,a maximum content of soluble phosphate of745.861mg/L predicated by the modelequation was achieved at31.4°C, pH7.08and water content73.2%, meanwhile, amaximum content of soluble potassium of1467.64μg/L was achived at30.9°C, pH7.13and water content73.0%, and a maximum content of N2-fixing of1511mg/Lwas achived at31.2°C, pH7.15and water content74.5%. Subsequent proving testdemonstrated the content of soluble phosphate, soluble potassium and total nitrogenreached744.745mg/L,1463.96μg/L and1503.79mg/L, respectively.In the pot experiment, SMS biofertilizer produced by these fifteen microorganismmade the available P, K and total N in soil and plant dry weight reached to113.37mg/Kg,367.6137mg/Kg,731.461mg/Kg and0.5478g, which increased by14.2%,10.9%,11.1%and12.9%compared with the biofertilizer produced by FL7, K3andN1, respectively.