Alvarez Belén, López María M, Biosca Elena G
Instituto Valenciano de Investigaciones Agrarias, Carretera Moncada-Náquera, km 4.5, Moncada 46113, Valencia, Spain.
Appl Environ Microbiol. 2007 Nov;73(22):7210-7. doi: 10.1128/AEM.00960-07. Epub 2007 Sep 14.
Ralstonia solanacearum phylotype II biovar 2 causes bacterial wilt in solanaceous hosts, producing severe economic losses worldwide. Waterways can be major dissemination routes of this pathogen, which is able to survive for long periods in sterilized water. However, little is known about its survival in natural water when other microorganisms, such as bacteriophages, other bacteria, and protozoa, are present. This study looks into the fate of a Spanish strain of R. solanacearum inoculated in water microcosms from a Spanish river, containing different microbiota fractions, at 24 degrees C and 14 degrees C, for a month. At both temperatures, R. solanacearum densities remained constant at the initial levels in control microcosms of sterile river water while, by contrast, declines in the populations of the introduced strain were observed in the nonsterile microcosms. These decreases were less marked at 14 degrees C. Lytic bacteriophages present in this river water were involved in the declines of the pathogen populations, but indigenous protozoa and bacteria also contributed to the reduced persistence in water. R. solanacearum variants displaying resistance to phage infection were observed, but only in microcosms without protozoa and native bacteria. In water microcosms, the temperature of 14 degrees C was more favorable for the survival of this pathogen than 24 degrees C, since biotic interactions were slower at the lower temperature. Similar trends were observed in microcosms inoculated with a Dutch strain. This is the first study demonstrating the influence of different fractions of water microorganisms on the survival of R. solanacearum phylotype II released into river water microcosms.
青枯雷尔氏菌II型生理小种2引起茄科寄主植物的青枯病，在全球造成严重经济损失。水道可能是这种病原菌的主要传播途径，它能够在灭菌水中长期存活。然而，当存在其他微生物，如噬菌体、其他细菌和原生动物时，对于其在天然水中的存活情况却知之甚少。本研究调查了一株来自西班牙的青枯雷尔氏菌菌株接种到取自西班牙一条河流的水微宇宙中的命运，该水微宇宙含有不同的微生物群落组分，在24℃和14℃下放置一个月。在这两个温度下，在无菌河水的对照微宇宙中，青枯雷尔氏菌的密度在初始水平保持恒定，而相比之下，在非无菌微宇宙中观察到引入菌株的数量下降。这些下降在14℃时不太明显。该河水中存在的裂解性噬菌体参与了病原菌数量的下降，但本地原生动物和细菌也导致了其在水中持久性的降低。观察到了对噬菌体感染具有抗性的青枯雷尔氏菌变体，但仅在没有原生动物和本地细菌的微宇宙中出现。在水微宇宙中，14℃比24℃更有利于这种病原菌的存活，因为在较低温度下生物相互作用较慢。在用一株荷兰菌株接种的微宇宙中也观察到了类似趋势。这是第一项证明不同组分的水微生物对释放到河水微宇宙中的青枯雷尔氏菌II型存活影响的研究。
