4株茶树根际促生菌菌株的鉴定及促生作用

Identification of four plant growth-promoting rhizobacteria isolated from tea rhizosphere

摘要:

【背景】根际促生菌可以促进植物生长、提高植物抗性。茶树根际具有特殊的根土微生物生境，可以获得具促生作用的有益微生物。【目的】探究4株茶树根际促生菌菌株的分类地位及促生作用，筛选优良的根际促生菌菌株。【方法】通过形态、生理生化特征、16S rRNA基因序列同源性比对鉴定4株茶树根际促生菌，采用钼锑抗比色法测定溶磷量，通过比色法测定ACC脱氨酶活性、CAS法测定产铁载体能力、Salkowski法测定产IAA (Indoleacetic acid)的能力进行促生作用研究，通过盆栽实验测试白菜、空心菜、苋菜及水稻的株高及鲜重以分析促生效应。【结果】鉴定KKS-6-N1为放射型土壤杆菌(Agrobacterium radiobacter)，KKS-7-N7为铜绿假单胞菌(Pseudomonas aeruginosa)，GD3为Pseudomonas hunanensis，GD12为弯曲芽孢杆菌(Bacillus flexus)。固氮菌株KKS-6-N1可产铁载体；固氮菌株KKS-7-N7具有解磷及产铁载体能力，分泌的IAA含量高达101.29 mg/L；解钾菌株GD3具溶磷能力，分泌的ACC脱氨酶酶活为8.09 μmol/(mg·h)，相对铁载体含量为0.31；具固氮解钾性能的菌株GD12分泌的ACC脱氨酶活性为14.46 μmol/(mg·h)。盆栽试验表明，4个菌株对白菜、空心菜、苋菜的株高和鲜重均有明显促进作用，尤以GD3效果更甚。【结论】茶树根际促生菌菌株Pseudomonas hunanensis GD3促生作用显著，具有开发成微生物菌肥的潜力。

Abstract:

[Background] Plant growth-promoting rhizobacteria can promote plant growth and improve stress tolerance. There are special microbial habitats on tea rhizosphere and some beneficial microorganisms with growth-promoting effects could be easily acquired. [Objective] To ascertain taxonomic status and study growth-promoting characteristics of four PGPR strains isolated from tea rhizosphere, and further screen superior PGPR strain. [Methods] These four strains were identified based on morphological, physiological and biochemical characteristics, homology alignments of 16S rRNA gene sequences. The plant growth-promoting characteristics of isolates were studied. Phosphorus contents were analyzed with Mo-Sb colorimetry. ACC (1-Aminocyclopropane-1-carboxylic acid) deaminase activity was measured by colorimetric method. Also, siderophere secreting capacity and IAA content were determined by quantitative test of CAS (Chrome zaurol S) medium and method of Salkowski, respectively. In pot experiments, plant growth-promoting effects were analyzed by measuring shoot heights and fresh weights of tested plants (including Chinese cabbage, swamp cabbage, amaranth and rice). [Results] The strain KKS-6-N1 was identified as Agrobacterium radiobacter, KKS-7-N7 identified as Pseudomonas aeruginosa, GD3 identified as Pseudomonas hunanensis, and GD12 identified as Bacillus flexus, respectively. In these four strains, nitrogen-fixing strains KKS-6-N1 and KKS-7-N7 produced siderophore, KKS-7-N7 also had the abilities of phosphorus-dissolving and IAA secreting as high as 101.29 mg/L. The other two strains, potassium-solubilizing strain GD3 still dissolved phosphorus, its ACC deaminase activity was 8.09 μmol/(mg·h) and relative content of siderophore was 0.31. whereas GD12, which had dissolved potassium and fixed nitrogen, was found to secret ACC deaminase of 14.46 μmol/(mg·h). In pot experiments, shoot heights and fresh weights of Chinese cabbage, swamp cabbage and amaranth were increased obviously by inoculation of these four strains, especially GD3 is the most excellent among them. [Conclusion] Pseudomonas hunanensis GD3, which isolated from tea rhizosphere, could strongly promote plant growth. And it is possible to develop as an excellent microbial fertilizer.