南海东海岛近海固氮细菌多样性及对菜心的促生作用

Diversity and growth promotion of nitrogen-fixing bacteria isolated from the offshore of Donghai Island in the South China Sea

摘要:

海洋固氮细菌在自然界氮循环中发挥着重要作用，筛选和开发海洋固氮促生的菌种资源，对于生物菌肥的开发应用和农业生产具有重要意义。[目的]研究海洋固氮细菌的生物多样性及对陆地作物的促生作用，筛选优良的植物根际促生菌株。[方法]通过形态特征、生理生化试验和16SrRNA基因序列比对进行菌属鉴定；将解磷、解钾、产蛋白酶和纤维素酶等性能优良的菌株作为菜心盆栽试验的组合菌液，探究对菜心能否起促生作用。[结果]本研究从南海东海岛的海岛沉积物中筛选出18株固氮菌，分布在6个属9种，不动杆菌属4株，假交替单胞菌属1株，芽孢杆菌属8株，嗜冷杆菌属1株，海单胞菌属1株，交替单胞菌属3株。菜心幼苗经过组合菌剂的浇灌，在茎高、茎粗、最大叶宽和最大叶长4个指标均表明对菜心有显著的促生作用。其中，以芽孢杆菌属和不动杆菌属的菌株在菜心的生长过程中起关键的促进作用，对菜心的促生性能最佳。[结论]南海近海具有种类丰富多样的固氮细菌，以芽孢杆菌属和不动杆菌属的菌株促生作用最为显著，具有开发成微生物菌肥的潜力，为优良的海洋促生微生物菌种资源的定向利用及蔬菜的无公害生产提供重要依据。

关键词:固氮细菌;南海近海;种群分布;促生作用

Abstract:

[Objective] We studied the diversity and crop-growth promotion of marine nitrogen-fixing bacteria and screened for excellent plant rhizosphere-promoting strains. [Methods] We identified the representative strains by morphological, physiological and biochemical characteristics, and 16S rRNA gene sequence alignment analysis. We used strains with excellent properties as the combined bacterial liquids in the pot-planting test. [Results] We isolated a total of 18 nitrogen-fixing bacteria from the offshore of Donghai Island in the South China Sea, which were classified into 9 species of 6 genera, belonging to 4 strains of the genus Acinetabacter, 1 strain of the genus Pseudoalteromonas, 8 strains of the genus Bacillus, 1 strain of the genus Psyctrobacter, 1 strain of the genus Oceanimonas and 3 strains of the genus Alteromonas. The seedlings of Chinese flowering cabbage were irrigated by combined microbial agents. Among them, the strains of the genera Bacillus and Acinetobacter had a key promoting effect in the growth process of Chinese flowering cabbage, and showed the best growth promoting effect on Chinese flowering cabbage. [Conclusion] This study provides an important basis for the targeted utilization of marine microbial resources and the pollution-free production of vegetables.

Key words:nitrogen-fixing bacterium;South China Sea offshore;population and species distribution;growth promotion