Fons F, Amellal N, Leyval C, Saint-Martin N, Henry M
LIMOS, UMR 7131, CNRS-UHP Nancy I, Vandoeuvre-les-Nancy CEDEX, France.
Can J Microbiol. 2003 Jun;49(6):367-73. doi: 10.1139/w03-052.
Plant secondary metabolites, such as saponins, have a considerable impact in agriculture because of their allelopathic effects. They also affect the growth of soil microorganisms, especially fungi. We investigated the influence of saponins on rhizosphere bacteria in vitro and in soil conditions. The effects of gypsophila saponins on the growth kinetics of rhizosphere bacteria were studied by monitoring the absorbance of the cultures in microtiter plates. Gypsophila saponins (1%) increased the lag phase of bacterial growth. The impact of gypsophila saponins on subterranean clover rhizosphere was also investigated in a pot experiment. The addition of gypsophila saponins did not modify clover biomass but significantly increased (twofold with 1% saponins) the weight of adhering soil. The number of culturable heterotrophic bacteria of the clover rhizosphere was not affected by the addition of gypsophila saponins. Nevertheless, the phenotypical characterization of the dominant Gram-negative strains of the clover rhizosphere, using the Biolog system, showed qualitative and quantitative differences induced by 1% saponins. With the addition of saponins, the populations of Chryseomonas spp. and Acinetobacter spp., the two dominant culturable genera of control clover, were no longer detectable or were significantly decreased, while that of Aquaspirillum dispar increased and Aquaspirillum spp. became the major genus. Aquaspirillum dispar and Aquaspirillum spp. were also the dominant rhizosphere bacteria of Gypsophila paniculata, which greatly accumulates these saponins in its roots. These results suggest that saponins may control rhizosphere bacteria in soil through rhizodeposition mechanisms.
植物次生代谢产物，如皂苷，因其化感作用而在农业中具有相当大的影响。它们还会影响土壤微生物尤其是真菌的生长。我们在体外和土壤条件下研究了皂苷对根际细菌的影响。通过监测微孔板中培养物的吸光度，研究了满天星皂苷对根际细菌生长动力学的影响。满天星皂苷（1%）延长了细菌生长的延迟期。在盆栽试验中还研究了满天星皂苷对地下三叶草根际的影响。添加满天星皂苷并未改变三叶草的生物量，但显著增加了（1%皂苷时增加了两倍）附着土壤的重量。添加满天星皂苷对三叶草根际可培养的异养细菌数量没有影响。然而，使用Biolog系统对三叶草根际优势革兰氏阴性菌株进行的表型特征分析表明，1%皂苷诱导了定性和定量的差异。添加皂苷后，对照三叶草的两个优势可培养属金黄杆菌属和不动杆菌属的种群不再可检测到或显著减少，而不同螺菌增加，不同螺菌属成为主要属。不同螺菌和不同螺菌属也是圆锥石头花根际的优势细菌，圆锥石头花在其根部大量积累这些皂苷。这些结果表明，皂苷可能通过根际沉积机制控制土壤中的根际细菌。
