Selection of dominant bacteria for phosphate liberation in calcareous soil
石灰性土壤中解磷优势菌的筛选研究

B2 and B67 were identified as two best bacteria to promote phosphate liberation from crops rhizosphere.During incubation in culture media with B2 and B67,the phosphate dissolved circles in plate culture,i.e.D/d values,are 5.1 and 3.8 respectively for B2 and B67.More than one kind of organic acids,including malic acid,malonic acid,oxalic acid and lactic acid,are produced and the total amount of acid is 28.25 and 19.78 times of control,respectively.Further the pH of culture media decline 2.3 and 1.1 units,respectively.When four soil samples,collected from different areas,are incubated with the above culture media for 20 days under the conditions of constant temperature and humidity,available phosphate in four soil samples is enhanced by B2 and B67. Available phosphate contents are 2.64,3.04,1.71 and 2.20 times of four control samples,respectively when the above four soil samples are incubated with B2;whereas available phosphate contents are 2.12,1.90,1.35 and 1.78 times of four control samples,respectively when the above four soil samples are incubated with B67.Also it is found that phosphate lyolysis is positively related to the available number of bacteria and phosphatase activity in soil.