盐胁迫下草地早熟禾出苗期可培养细菌多样性与促生功能研究

Diversity and growth-promoting function of culturable bacteria at seedling stage of Poa pratensis under salt stress

摘要:

【目的】 解析200 mmol/L NaCl胁迫下草地早熟禾（Poa pratensis）可培养细菌群落多样性，筛选兼具耐盐性和促生功能的菌株，为盐渍土生物改良提供理论依据和菌种资源。【方法】 采用稀释涂布法分离草地早熟禾品种优美和新月出苗期茎、叶与根的可培养细菌，结合菌株耐盐性及其固氮、溶磷、 解钾、产IAA和产胞外酶能力，筛选盐胁迫响应菌株。【结果】 27株可培养细菌隶属于3门13属。对照组中，优美和新月地上部分优势属分别为假单胞菌属（Pseudomonas）和金黄杆菌属（Chryseobacte- rium），地下部分优势菌属分别为假单胞菌属和土壤杆菌属（Agrobacterium）。与对照组相比，假单胞菌属数量在优美和新月盐胁迫组中分别增加了61.78%和51.67%，增至7.64×103 CFU/g和4.8× 103 CFU/g。27株细菌中，L7（假单胞菌属）、L27和B2（芽孢杆菌属Bacillus）耐盐阈值高达20%，且具有多种促生功能。【结论】 盐胁迫对草地早熟禾组织中可培养细菌群落结构影响显著，菌株L7、L27和 B2为促生功能优良的耐盐菌株。本研究为盐渍化草地中的早熟禾生物修复功能提升奠定了理论基础和细菌资源。

Abstract:

【Objective】 To analyze the diversity of bacterial community cultured by Poa pratensis under 200 mmol/L NaCl stress，and screen strains with both salt tolerance and growth-promoting functions，so as to provide theoretical basis and strain resources for biological improvement of saline soil.【Method】 The culturable bacteria from stem，leaf and root of Youmei and Xinyue cultivars were isolated by dilution coating method，and the strains respon sive to salt stress were screened by combining their salt tolerance，nitrogen fixation，phosphorus dissolution，potas sium dissolution，IAA production and extracellular enzyme production abilities.【Result】 A total of 27 culturable bac teria belong to three phyla and 13 genera. In the control group，the dominant genera in the above-ground parts of Youmei and Xinyue were Pseudomonas and Chryseobacterium，respectively，and the dominant genera in the under ground parts were Pseudomonas and Agrobacterium，respectively. Compared with the control group，the number of Pseudomonas increased by 61. 78% and 51. 67% to 7. 64×103 CFU/g and 4.8×103 CFU/g in the Youmei and Xinyue salt stress groups，respectively. Among the 27 bacteria strains，L7 （Pseudomonas），L27 and B2 （Bacillus） have salt tolerance thresholds as high as 20%，and have various growth-promoting functions.【Conclusion】 Salt stress has a significant effect on the community structure of culturable bacteria in grassland Poa pratensis tissues. Strains L7，L27 and B2 were screened out as salt-tolerant strains with excellent growth-promoting functions， which laid a theoretical foundation and bacterial resources for improving the bioremediation function of Poa pratensis in salinized grassland.