Screening And Medium Optimization Of Phosphate-solubilizing,Potassium-solubilizing Microorganism

Phosphorus-solubilizing and potassium-solubilizing microbial fertilizers are the hotspots of microbial fertilizer research.In recent years,with the increasingly prominent land problems such as soil compaction and land salinization,microbial fertilizers have developed faster and faster,making microbial fertilizers gradually accepted by everyone.Phosphorus-dissolving and potassium-solubilizing bacterial fertilizers mainly include three kinds of microbial bacteria such as phosphorus-solubilizing bacteria,phosphate-solubilizing bacteria,and potassium-releasing bacteria,and they are mainly used for dissolving phosphorus,potassium-related salts,minerals,and the like that cannot be directly absorbed by crops in soil.It is a soluble element of phosphorus and potassium for the absorption and utilization of crops,supplements the phosphorus and potassium content of plants,promotes crop growth,increases crop yield,and enhances crop resistance.In this study,functional bacteria screened from PGPR eXperiments,such as peony,tobacco,peanut,alfalfa,banana,sedum,pineapple,winter jujube,distiller's grains,and blueberry,were screened for the functions of dissolving phosphorus,dissolving phosphorus,and dissolving potassium.The single strain pot eXperiment was conducted on the strains with the functions of solubilizing phosphorus,dephosphorizing,and dissolving potassium.Selection of potted plants for screening,identification,antagonistic eXperiments,etc.The potted strains with the best function were screened in combination pot eXperiments,the strains were optimized for the culture medium.From PGPR Lab,functional strains screened from plants such as alfalfa,banana,sedum,tobacco,peony,lees,and pineapple can be collectively sorted,numbered,and preserved.Phosphorus dissolving,phosphate-solubilizing,and potassium-solubilizing functions were screened for the 1140 strains that had been sorted out,and the function of the strains was screened repeatedly to obtain 11 strains of phosphorus-solubilizing bacteria with stable functions,60 strains of phosphorus-solubilizing bacteria,and 157 potassium-solubilizing bacteria.Potted eXperiments were carried out on the selected strains of phosphorus-solubilizing,phosphate-solubilizing,and potassium-solubilizing strains,and the selected crop was a cucumber seedling.The reason why cucumber was selected as the eXperimental object was that the relative growth period of cucumber was relatively fast,and it was relatively sensitive to the treatment of eXternal factors.The eXperimental group and the control group could produce a large difference to facilitate the comparison of observation and data measurement.After a single-strain pot eXperiment,the comparison of the plant height,stem diameter,fresh weight of the root,fresh weight of dry weight of the aboveground part,the agronomic traits of the leaf weight of the aboveground part,the number of branches of the leaves,and the variation of phosphorus and potassium contents in the soil were obtained.The strains with good pot eXperiment were 4 strains of phosphate-solubilizing bacteria,5 strains of potassium-solubilizing bacteria,1 strain of phosphorus-solubilizing bacteria,and 9 strains with both potassium-solubilizing and phosphate-solubilizing functions.After analyzing the potted planting results,one strain of phosphate-solubilizing bacteria,two strains of potassium-solubilizing bacteria,one strain of phosphate-solubilizing bacteria,and two strains that have both the functions of phosphate-solubilizing and potassium-solubilizing were selected to carry out compound pot e Xperiments.Before the compound pot eXperiment,the siX strains were further tested for function,colony morphology,strain identification,and antagonistic eXperiments between the strains.A phylogenetic tree was established based on the 16S rDNA sequence of the strain.Through the identification of the selected si X strains,strain GQJK61 and strain JTYP2 can be identified as Bacillus velezensis,strain GQJK60 is Bacillus tequilensis,and strain YP3N101 is Bacillus aerius.I140 and I42 are Enterobacter ludwigii.Observe and record some of the e Xternal morphology of the colonies.After functional verification,the strains are still in good effect,and eliminate the combination of antagonistic effects between the strains.Afterwards,6 strains were combined in 6combinations to perform the pot eXperiment of the composite strains.According to the data of the pot eXperiment,the optimal strain combination scheme was determined.The strains YP3N101 and I42 selected from the combination were used to optimize the culture medium.The optimization process of the culture medium was based on bean sprouts culture medium,and the most suitable carbon source,nitrogen source,and inorganic salt species were determined by single factor e Xperiments.In the single factor eXperiments,the carbon sources used were sucrose,glucose,maltose,soluble starch and corn starch,the organic nitrogen sources were beef eXtract,peptone,yeast powder,and soybean meal,the inorganic nitrogen sources were?NH₄?₂SO₄,NH₄NO₃,NH₄Cl,and urea,The inorganic salts are MgSO₄,CaCO₃,K₂HPO₄,KH₂PO₄.After the single factor optimization eXperiment was completed,the optimal factors for the culture medium were selected and orthogonal eXperiments were designed based on orthogonal design tables to determine the optimal ratio of each factor in the growth medium of the strain.The optimal carbon source of strain YP3N101 is 3%glucose,the optimal organic nitrogen source is 1.5%peptone,the optimal inorganic nitrogen source is 0.3%NH₄NO₃,and the optimal inorganic salt is 0.3%CaCO₃.The optimal carbon source of strain I42 was 3%sucrose,the optimal organic nitrogen source was 1.5%yeast powder,the optimal inorganic nitrogen source was 0.3%NH₄Cl,and the optimal inorganic salt was 0.3%KH₂PO₄.