Isolation And Identification Of Phosphate-solubilizing Microorganism From Soil

In order to obtain the strains with potential applications of microbialfertilizer, phosphate-solubilizing microorganisms(PSM) are screened from35soilsamples collected from Xinyang, Zhengzhou,Xuchang and so on, in Henan procince,using the selective medium. Firstly, the phosphate-solubilizing activity of PSM wasdetermined by Mo-Sb colorimetry, and the antifungal activity of PSM was assayed bydual culture method. Secondly, the growth promoting effect of PSM on tomato plantwas investigated under greenhouse conditions. Finally, taxonomy of PSM wasconducted with analysis of the16S rDNA and ITS sequences based on thedetermination of morphological physiological and biochemical characteristics. Theresults were as follows:1. A total of53phosphate-solubilizing bacteria(PSB) and7inorganic phosphatesolubilizing fungis(PSF) were obtained from the35soil samples by the duel culturetests. Among the53PSB,30strains belong to inorganic PSB and23strains belong toorganic PSB.2. The capacities of53PSB and7PSF were tested by Mo-Sb colorimetry,respectively. The results showed that all test strains could solubilize calciumcarbonate and lecithin into dissoluble phosphorus in degree. The phosphatesolubilizing activites of PSF were higher than that of PSB. The activity of PSF strainWPFJ1was180.00μg/mL, while PSB strain WP1was165.72μg/mL.3. Results of dual test showed that15stains of PSB inhibited to Alternaria solani,Colletotrichum orbiculare, Fusarium graminearum, Gaeumannomyces graminis var.tritici, Rhizoctonia cerealis and Ustilaginoidea oryzae.4. The growth promoting effect of strains WP1, WP-BT2-8, YP21and WPFJ1,single and combination, on tomato plant were investigated with pot experiment undergreenhouse conditions. Results indicated that all test strains could promoted growth oftomato plant, and the growth promoting effect of strain WPFJ1was the mostdistinguished in single test, and that of the complex group of strains WP1+WP-BT2-8was was the most distinguished in combination test.5. The growth curves of strain WP1,WP-BT2-8,WPFJ1and YP21were measured.The results showed that4strains could release soluble P from substrate under the lack of soluble P.The pH values of fermentation broth decreased gradually duringinorganic PSM developtment. It suggested that the phosphate solubilizing activity ofinorganic PSM strain was related to acid secretion; The pH values of fermentationbroth showed little change during organic PSB incubation, it suggested that thephosphate solubilizing mechanisms maight be related to enzymolysis.6. The analysis of the16S rDNA sequences of53PSB strains and ITS sequencesof7PSF strains were conducted. The results showed that53PSB strains belonged to7Genus, and more than18species, such as Bacillus, Paenibacillus, Pseudomonas,Burkholderia, Enterobacter, Acinetobacter and Serratia, which indicated thebiodiversity of PSB was abundant in soil of Henan province.7PSF strains belongedto Penicillium, Aspergillus and Chaunopycnis, respectively. As the available PSM,strain WP1was identified as Burholderia stabilis, strains WP-BT2-8and YP21wereidentified as Paenibacillus polymyxa, and strain WPFJ1was identified as Aspergillusniger.