Identification Of The Phosphate Solubilizing-related Genes In Endophytic GZJR-8 And The Physiology And Biochemistry Characteristic Of LTYR-11 And LTJR-57

The demand of phosphorus in agricultural production is only lower than nitrogen.Under natural conditions,soluble phosphorus,which can be absorbed and used,is often a class of mineral nutrition that limits agricultural production.Endophytic bacteria Pseudomonas sp.GZJR-8 was isolated from the stem of Hylomecon japonica,and it was initially identified that GZJR-8 had a effect of dissolving phosphorus.In this study,the function of pqqE and GDH genes of GZJR-8 in phosphate solubilization was identified.The genes pqqE and GDH were knocked out respectively by the homologous recombination technology,and we constructed the complementary strain of the mutant by electro transformation.For the wild-type,mutant and complementary strain,we tested whether they produced soluble phosphorus ring by insoluble inorganic phosphate mediumn(PKO)and total available phosphorus and pH by ascorbic acid-molybdenum blue coloration phosphorus measurement.The results showed that pqqE and GDH genes were phosphate solubilixing-related genes in GZJR-8,in which the phosphorus solubilizing capacity of the mutants decreased,but it did not completely lose,the complementary strains can restore the ability to dissolve phosphorus.This strain could dissolve phosphorus through the acid-producing mechanism,could promote plant growth.The strain has potential application value in agricultural production.The strains LTYR-11 and LTJR-57 were isolated from leaves and stems of Alhagi sparsifolia Shap.,and sequence analysis and phylogenetic analysis of 16 S rRNA gene showed that the two strains belonged to the genus Bosea and Blastococcus,the closest pattern strains were Bosea vaviloviae Vaf-18T(95%)and Blastococcus saxobsidens BC448T(98.8%)respectively.The similarity of the sequences with the known pattern strains suggested that the two strains might be potential new taxonomic units.Subsequently,the culture conditions,growth temperature,growth pH,salt tolerance,antibacterial activity,various enzyme activities,iron-producing vector and other physiological and biochemical indexes of these two endophytic bacteria were tested.The results showed that: For Bosea sp.LTYR-11,Its optimum growth conditions were 0.1TSA and NA medium.It grew well at 30-37 ? and stopped at 44 ?,pH 7.5-8,0-1% content of NaCl and stopped in 1.5%,it could not be grown in an anaerobic environment,could swim.It also had a very strong ability of iron-producingcarrier and degreased hydrogen peroxide,urea and other enzyme activities.For Blastococcus sp.LTJR-57,Its optimum growth conditions were MA medium.It grew well at 37-44 ? and stopped at 50 ?,pH 9,grew under alkaline conditions,0% content of NaCl and stopped in4%.It also had a ability of iron-producing carrier,improving the utilization of iron ions,and degreased skim milk(casein),tyrosine,hydrogen peroxide(strong),urea and other enzyme activities.