Fluorescent Pseudomonas-FAP2 and Bacillus licheniformis interact positively in biofilm mode enhancing plant growth and photosynthetic attributes
Fluorescent Pseudomonas-FAP2 and Bacillus licheniformis interact positively in biofilm mode enhancing plant growth and photosynthetic attributes
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DOI：
10.1038/s41598-019-40864-4
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发表时间：
2019-03-14
影响因子：
4.6
通讯作者：
Ahmad, Iqbal
中科院分区：
文献类型：
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作者：
Ansari, Firoz Ahmad;Ahmad, Iqbal
常用植物促生根瘤菌（PGPR）在体外和根际生物膜模式下的相容性相互作用，有望为开发有效的联盟提供更好的认识。基于上述假设，本研究采用标准方案评估了两种特征PGPR（荧光假单胞菌FAP2和地衣芽孢杆菌B642）的生物膜相关功能。采用板斑/覆盖法和竞争生长评价法研究了浮游模式下FAP2与B642的相互作用。用标准方法研究了微滴板和玻璃表面生物膜的发育。利用扫描电镜对生物膜的形成进行了表征。通过测定土壤/根样品的CFU/g，研究了两种分离菌株单独接种和共接种对小麦幼苗根际和根面定殖的影响。通过扫描电镜进一步分析了根表面生物膜的发育情况。这两个分离株都表现出多种植物生长促进（PGP）特性（产生IAA、铁载体和氨；磷酸盐增溶）和生物膜相关功能，如产生EPS、海藻酸盐、细胞表面疏水性和群体运动。两种菌株在体外玻璃罩上形成了牢固的生物膜。两菌株在浮游模式下的相互作用在生长抑制和竞争生长动力学方面没有拮抗作用。同样，FAP2和B642菌株在玻璃覆盖片和幼苗根部形成混合生物膜。从单次接种和共接种的活菌数可以看出，这两种分离株在小麦根际和根际均有定殖。与未接种对照相比，单次接种和共接种显著提高了幼苗的营养生长和光合参数，如叶绿素含量、蒸腾速率(E)、内部CO2浓度（Ci）、气孔导度（g(s)）、净光合速率（P-N）和叶片水势（LWP）。本土菌株荧光假单胞菌FAP2和地衣芽孢杆菌B642在浮游和生物膜两种生长模式下都是兼容的PGPR，因此可以建立有效的PGPR组合。自然条件下生物膜生长模式下相互作用的分子机制有待进一步深入研究。
Compatible interaction between commonly used plant growth promoting rhizobacteria (PGPR) in biofilm mode in vitro and in the rhizosphere is expected to provide better understanding for the development of effective consortium. With the above hypothesis, the present study evaluated two characterized PGPR (Pseudomonas fluorescens FAP2 and Bacillus licheniformis B642) for their biofilm-related functions using standard protocols. The interaction between the FAP2 and B642 in planktonic mode was studied by plate spot/overlay method and competitive growth assessment. Biofilm development on a microtitre plate and a glass surface was studied by standard methods. Biofilm formation was characterized by SEM. Rhizosphere and rhizoplane colonization of wheat seedlings by both isolates individually and by co-inoculation was studied by determining CFU/g of soil/root samples. Biofilm development on the root surface was further analyzed by SEM. Both isolates demonstrated multiple plant growth promoting (PGP) traits (production of IAA, siderophore, and ammonia; phosphate solubilization) and biofilm-related functions such as production of EPS, alginate, cell surface hydrophobicity and swarming motility. Both strains formed strong biofilms on a glass cover slip in vitro. Interaction between the two strains under the planktonic mode revealed no antagonism in terms of growth inhibition and competitive growth kinetics. Similarly, FAP2 and B642 strains formed a mixed biofilm on a glass cover slip as well as on seedling roots. Wheat rhizosphere and rhizoplane were colonized by both isolates as evidenced from their viable counts in single and co-inoculation. The effect of single and co inoculation revealed the significant enhancement of vegetative growth and photosynthetic parameters such as chlorophyll content, transpiration rate (E), internal CO2 concentration (Ci), stomatal conductance (g(s)), and net photosynthetic rate (P-N) and leaf water potential (LWP) as compared to uninoculated control. Indigenous Pseudomonas fluorescens FAP2 strain and Bacillus licheniformis B642 are compatible PGPR in both planktonic and biofilm modes of growth and threfore could be developed effective consortium of PGPR. Further indepth investigation is required to understand molecular mechanism of the interaction in biofilm mode of growth under natural condition.