海洋细菌解淀粉芽胞杆菌BA-3在兰花的定殖及对根际微生态的影响

为明确海洋细菌解淀粉芽胞杆菌BA-3在兰花根际的定殖特性,本研究采用抗生素标记法筛选出对利福平和卡那霉素稳定的菌株BA-3-K。平板对峙试验证明,菌株BA-3-K对兰花茎腐病抑菌率达86.91%,与原始菌株BA-3抑菌率87.69%无明显差异。采用灌根法和涂茎法证实了标记菌株BA-3-K能在兰花植株体内定殖达60 d以上。灌根处理表明,生防菌BA-3-K的定殖数量为土壤>根>茎,呈先升后降的趋势,第21d在根部和茎部达到最大分别为2.54×10^5和1.47×10^5cfu/g,在土壤中第15d达到最大6.50×10^5cfu/g,但叶部未检测到标记菌株BA-3-K;涂茎处理生防菌的定殖量茎>叶,第17 d在茎部达到最大2.33×10^5cfu/g,随后呈下降趋势,根部和土壤未检测到标记菌株BA-3-K;通过扫描电镜定性观察,发现BA-3-K可在植株茎部定殖。盆栽试验表明,菌株BA-3-K施用后,根际土壤中细菌、真菌和放线菌的数量明显高于对照处理。本研究表明海洋细菌BA-3有较强的定殖能力,具有良好的应用价值。

Colonization Dynamics Marine Bacterium Bacillus amyloliquefaciens BA-3 and Its Impact on the Microbial Community of Cymbidium Rhizosphere

Marine bacterium strain BA-3 was applied to cymbidium plants to investigate the colonization features and the impact on the microbial community of Cymbidium rhizosphere. Mutant strain BA-3-K with stable marker of antibiotic and inhibitory effect against Fusarium oxysporium of cymbidium were screened by using the rifampin and kanamycin-resistant mutants and dual culture method. Plate confrontation test proves that the inhibition rates of strain BA-3-K and original strain BA-3 against Fusarium oxysporium were 86.91% and 87.69%. It was verified that the strain BA-3-K could colonize for 60 days or more in cymbidium by root irrigating and stem daubing. After root irrigating, the colonization quantity of strain BA-3-K trended to increase firstly and then decrease. The highest quantity in roots and stems were 2.54×10⁵ cfu/g and 1.47×10⁵ cfu/g at 21 d, in soil were 6.50×10⁵ cfu/g at 15 d after inoculation, respectively. Bacteria quantities in different parts were soil > root > stem and strain BA-3-K wasn't detected in leaf. After stem daubing, the highest colonization quantity in stem was 2.33×10⁵ cfu/g at 17 d after inoculation and then decreased. Bacteria quantities in different parts were stem>leaf. and strain BA-3-K wasn't detected in root and soil. The strain BA-3-K could colonize in stem of cymbidium by scanning electron microscope. Pot tests demonstrated that the quantities of bacteria, fungi and actinomycetes in rhizosphere soil was significantly higher than that in control by root irrigating with strain BA-3-K. The results indicated that marine bacterium strain BA-3 has strong colonization ability and good application value.