Screening Of A Phosphate Dissolving Bacteria Strain And It's Culture Conditions Optimization

Phosphorus is one of the essential elements for the growth of plant.However,the phosphorus-deficient farmland soil area takes up two thirds of the total land soil area.Applying phosphorus fertilizer is an important means of growing agricultural product due to current status of acute shortage of phosphorus in cultivated soil.In china,the utilization ratio of phosphate fertilizer is only 10%?20%in a quarter,resulting in quantity of vestigial phosphorus in the soil becoming insoluble phosphorus,which forms huge phosphorous pools in the soil.Phosphate-soluble microorganisms are able to dissolve insoluble phosphorus into soluble phosphorus,which is available for plant to uptake and exploit.Phosphate-soluble microorganisms have gradually become the focus of current research.This research focuses on screening highly efficient phosphate-solubilizing bacteria,using industrial organic wastewater as nutrient sources,optimizing fermentation culture conditions.The research not only eases the pressure of waste disposal,but also provides the theoretical basis for applying Phosphate-soluble bacteria to agricultural production.Preliminary results obtained are as follows:?1?one strain with effective phosphate-solubilizing ability is selected,that is,Bacillus megaterium.Shake flask experiment for 7d,the degradation rate of Ca3?PO4?2 is 16.21%and the degradation rate of phosphate is 6.49%.?2?Monosodium glutamate fermentation liquid waste?MGW?is selected as cultivation nutrient source for Bacillus megaterium.Optimizing by orthogonal experiment,we obtained a better formulation for:beef extract 1.0g,peptone1.0g,MGW diluted 80 times,CaCO₃1.0g,MgSO4·7H₂O 1.0g?H₃BO₃ 0.02g?H₂O1000mL.?3?single factors shake flask culture experiment show that,the better fermentation conditions are:initial pH7.0?7.5,culture temperature 30??35?,culture time 36h,inoculum 5%,liquid-filled 10%,rotary speed 180r/min.?4?Shake flask culture feeding tests show that adding 50%MGW of the original recipe at the culture time 9h is able to enhance bacteria Bacillus megaterium.?5?Shake flask experiments controlled by two-step method show that,Adding Mn²⁺ in initial phase and in culture medium-term and adding Ca²⁺ in initial phase can improve the amount of spore at the end of the Bacillus megaterium culture.while adding Ca²⁺ in initial phase will inhibit the growth of bacteria.Increasing culture pH,temperature and rotary speed in culture medium-term can improve the number of spores.