油樟内生溶磷菌的筛选及其生物学特性

筛选具有溶磷能力的植物内生细菌，并探索该类菌的促生和抗逆性能，有助于扩大溶磷微生物来源、研发微生物肥料、改善土壤磷素营养和提高农业产量。该研究以从油樟组织中分离得到的50株内生细菌为材料，通过溶磷圈法初筛得到24株具有溶磷潜能的菌株，利用钼蓝比色法测定它们的溶磷能力和培养液的pH值，并研究溶磷能力较强菌株产生吲哚乙酸( IAA)、铁载体、1-氨基环丙烷-1-羧酸( ACC)脱氨酶、几丁质酶等促生和抗逆性能。结果表明：24株油樟内生细菌都能从磷酸钙中释放出有效磷(溶磷量为51.26~237.08μg·mL-1)，其中，YG60、YG43、YG36、YG25、YG49、YG44株菌的溶磷量较高，均大于150μg·mL-1。接种油樟内生菌后，培养液的pH值均有一定程度的降低，但菌株溶磷量与培养液pH值间不存在显著相关性。6株溶磷量大于150μg · mL-1的菌株大部分具有分泌IAA、产铁载体、ACC脱氨酶活性和几丁质酶活性的能力；其中YG43、YG60和YG25分泌IAA的能力较强(IAA分泌量分别为22.55、18.75和16.41μg·mL-1)，YG43和YG60产铁载体的能力较强(As/Ar小于0.6)，YG43、YG60和YG25的ACC脱氨酶活性(分别为0.194、0.224、0.208 U·mg-1)较高，YG43和YG60的几丁质酶活性(分别为2.968 U和2.502 U)较高。综合菌株的溶磷、促生和抗逆性能，认为YG43、YG60和YG25菌株在促进植物生长、提高植物抗性及生物防治方面具有较好的应用前景。

Screening and characterization of phosphate dissolving endophytic bacteria from Cinnamomum longepaniculatum

Screening endophytic strains with phosphate-dissolving and exploring the characterization of growth promo-ting and resistance were conducive to broad the phosphate dissolving microbial resources, to develop microbial fertiliz-ers, to improve soil phosphorus nutritious and to increase agricultural yield. We isolated 50 endophytic bacteria from interior tissues of Cinnamomum longepaniculatum, and 24 phosphate dissolving endophytic bacteria strains were screened using phosphate solubilizing zone ( PKO) inorganic culture medium, subsequently, the capacity of dissolving phosphorus of 24 strains were determined by phosphor-molybdate blue color methods, and the characteristics benefited to plant-microbe interaction-indoleacetic acid ( IAA) , siderophore, 1-aminocyclopropane-1-carboxylic acid deaminase ( ACC) and chitosanase activities were also evaluated. The results showed that 24 strains could release phosphate from tricalcium phosphate with the range of dissolving phosphate from 51.26 μg·mL-1 to 237.0 μg·mL-1, and the maxi-mum phosphate content in the solution was obtained with strain YG60. Among 24 strains, 6 strains ( YG60, YG43, YG36, YG25, YG49, YG44 ) showed the higher phosphate solubilization capacity ( 237. 08, 211. 53, 180. 68, 166.85, 151.28, 150.20 μg·mL-1 respectively) . Furthermore, 24 strains could decrease the pH of the medium with the pH value range from 4.5 to 5.5, and the relationship between pH and phosphorus solubizition was also discussed;however, there were no close relationship between them. The further experimental results showed that most of the 6 strains with higher phosphate dissolving capacity had the ability to produce IAA and siderophores, and had ACC deam-inase and chitosanase activity. Among them, YG43, YG60 and YG25 possessed higher IAA producing capacity (22.55, 18.75 and 16.41 μg·mL-1 respectively); YG43 and YG60 possessed higher siderophores of As/Ar<0.6 (0.459, 0.579 respectively );YG43, YG60 and YG25 had strong ACC deaminase activity (0.194, 0.224, 0.208 U·mg-1),YG43 and YG60 had strong chitosanase activity (2.968 U,2.502 U). In terms of all the properties of dis-solving phosphate, secreting IAA, siderophores, ACC deaminase and chitosanase, strains YG43, YG60 and YG25 isolated from interior tissues of C. longepaniculatum have abundant biological characteristics related to plant growth promotion, stress homeostasis regulation and biocontrol activity. They are possible to be further developed as excellent strains for application.