Phytopathology. 1999 Jun;89(6):470-5. doi: 10.1094/PHYTO.1999.89.6.470.
ABSTRACT The role of antibiotics in biological control of soilborne pathogens, and more generally in microbial antagonism in natural disease-suppressive soils, often has been questioned because of the indirect nature of the supporting evidence. In this study, a protocol for high pressure liquid chromatography/mass spectrometry is described that allowed specific identification and quantitation of the antibiotic 2,4-diacetylphloroglucinol (Phl) produced by naturally occurring fluorescent Pseudomonas spp. on roots of wheat grown in a soil suppressive to take-all of wheat. These results provide, for the first time, biochemical support for the conclusion of previous work that Phl-producing fluorescent Pseudomonas spp. are key components of the natural biological control that operates in take-all-suppressive soils in Washington State. This study also demonstrates that the total amount of Phl produced on roots of wheat by P. fluorescens strain Q2-87, at densities ranging from approximately 10(5) to 10(7) CFU/g of root, is proportional to its rhizosphere population density and that Phl production per population unit is a constant (0.62 ng/10(5) CFU). Thus, Phl production in the rhizosphere of wheat is strongly related to the ability of the introduced strain to colonize the roots.
摘要 由于支持证据的间接性质，抗生素在土壤病原菌生物防治中的作用，更广泛地说，在天然抑病土壤中的微生物拮抗作用中的作用，经常受到质疑。在本研究中，描述了一种高压液相色谱/质谱法的方案，该方案允许对在抑制小麦全蚀病的土壤中生长的小麦根上产生的天然荧光假单胞菌产生的抗生素 2,4-二乙酰基邻苯二酚（Phl）进行特异性鉴定和定量。这些结果首次为先前的工作提供了生化支持，即 Phl 产生的荧光假单胞菌是在华盛顿州全蚀病抑病土壤中起作用的天然生物防治的关键组成部分。本研究还表明，荧光假单胞菌 Q2-87 菌株在根际中产生的 Phl 总量与其根际种群密度成正比，其范围约为 10(5)至 10(7) CFU/g 根，并且每个种群单位的 Phl 产量是常数（0.62ng/10(5)CFU）。因此，小麦根际中 Phl 的产生与引入菌株在根中定殖的能力密切相关。
