Screening And Identification Of Phosphate-dissolving Bacteria In Black Soil Farmland And Their Biological Characteristic

About 95 % of phosphorus in soil is not directly available to plants.Phosphorus solubilizing bacteria are a group of functional microorganisms that can convert the ineffective phosphorus in soil into effective phosphorus that can be directly absorbed and used by plants through their reproduction and metabolism.In this study,we used the traditional dilution plate method and plate scribing method to screen and purify phosphorus solubilizing bacteria strains,and identified the pure strains of phosphorus solubilizing bacteria isolated by molecular biology sequencing technology,and explored their phosphorus solubilizing ability,phosphorus solubilizing characteristics,and the effect of promoting the growth of soybean potted plants.This study provides an important basis for establishing resource-saving and environment-friendly agricultural production methods.The main findings are as follows:(1)Twelve strains of phosphorus solubilizing bacteria were screened from black soil agricultural soil.12 strains of phosphorus solubilizing bacteria belonged to four families and four genera,among which three fungi,i.e.,WP5 were Penicillium spp.of the Cupressaceae family and WP8 and WP9 were Aspergillus spp.of the Aspergillus family;nine bacteria,i.e.,WP1,WP2,WP3 and WP4 and were Bacillus spp.of the Bacillus family and WP6,WP7,WP10,WP11 and WP12 were Pseudomonas spp.of the Pseudomonas spp.WP6,WP7,WP10,WP11 and WP12 were Pseudomonas spp.(2)All 12 strains of phosphate solubilizing bacteria were soluble in three common insoluble phosphates(tricalcium phosphate,iron phosphate and aluminum phosphate).Among them,WP1,WP6 and WP3 were significantly more soluble in tricalcium phosphate than other strains,and the effective phosphorus content of the fermentation supernatant was 520.84 mg/L,513.86 mg/L and 468.48 mg/L,respectively;WP3,WP5 and WP6 were more soluble in iron phosphate,and the effective phosphorus content of the fermentation supernatant was 508.97 mg/L,485.93 mg/L and 427.98 mg/L,respectively.The effective phosphorus content of the fermentation supernatant was508.97 mg/L,485.93 mg/L and 427.98 mg/L,respectively;WP4,WP1 and WP5 were more soluble in aluminum phosphate,and the effective phosphorus content of the fermentation supernatant was 624.17 mg/L,525.73 mg/L and 518.05 mg/L,respectively.(3)The phosphorus solubilization ability of 12 strains increased with the increase of incubation time(below 56 h)and incubation temperature(below 33 ℃);the strongest phosphorus solubilization ability was usually found under the condition of neutral p H;monosaccharides and disaccharides were the best carbon sources for most strains;ammonium and nitrate nitrogen were the best nitrogen sources for most strains.(4)Phosphorus in black soil is mainly in the form of Ca-P,so two strains of phosphorus solubilizing bacteria,WP1 and WP6,which are more soluble in tricalcium phosphate,were selected for verification in soybean pot tests.From the analysis of the results of the pot test,it was found that the effective phosphorus content in soybean interroot soil at day 80 of the WP1 and WP6 bacterial suspension root irrigation treatment was19.83 % and 7.54 % higher than that of the non-inoculated CK control.Meanwhile,the100-grain weight of soybean was 24.4 g,22.1 g and 20.4 g for WP1,WP6 and WP1+WP6treatments,respectively,which were higher than that of CK group.