Effect of root exudates and bacterial metabolic activity on conjugal gene transfer in the rhizosphere of a marsh plant
Effect of root exudates and bacterial metabolic activity on conjugal gene transfer in the rhizosphere of a marsh plant
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DOI：
10.1111/j.1574-6941.1998.tb00489.x
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发表时间：
1998-04-01
影响因子：
4.2
通讯作者：
Weber, D
中科院分区：
文献类型：
--
作者：
Kroer, N;Barkay, T;Weber, D
自然生境中细菌之间的基因交换被认为受到生长底物的可用性和生长速度的强烈影响。为了验证这一假设，将Rp4衍生物在荧光假单胞菌和沙雷氏菌之间的结合转移。在一个简单的沙/植物微观世界中进行了研究，并与根分泌物的有效性和细菌代谢活性有关。这种植物的存在极大地促进了转移。根际平均迁移比(T/D.R)为8.9×10(-11)，未受植物根系影响的沙地为5.5×10(-15)。该菌以根分泌物为生长底物，根际细胞的代谢活性([H-3]亮氨酸摄取)高于沙地(分别约1.0×10(-2)和0.5×10(-2)fmoL亮氨酸CFU-1h(-1))，与细胞密度有关。因此，观察到代谢活性和转移之间存在明显的相关性。然而，更多的实验表明，两者之间没有因果关系。当在含有根分泌物的沙子微宇宙中培养时，细菌的代谢活性增加，而配偶转移比率保持不变。因此，与公认的观点相反，根分泌物和代谢活动似乎不是刺激根际共生转移的原因。(C)1998年欧洲微生物学会联合会。爱思唯尔科学公司出版。
Genetic exchange between bacteria in natural habitats is believed to be strongly influenced by availability of growth substrates and growth rate. To test this hypothesis, conjugal transfer of an RP4 derivative between Pseudomonas fluorescens and Serratia sp. was studied in a simple sand/plant microcosm and was related to availability of root exudates and bacterial metabolic activity. The presence of the plant (Echinochlora crusgalli) greatly stimulated transfer. Average transfer ratios (T/D.R) were 8.9 x 10(-11) in the rhizosphere and 5.5 x 10(-15) in sand unaffected by the plant root. The bacteria used root exudates as growth substrate and depending on cell density, the metabolic activity ([H-3]leucine uptake) of the cells was higher in the rhizosphere than in the sand (around 1.0 x 10(-2) and 0.5 x 10(-2) fmol leucine CFU-1 h(-1), respectively). Thus, an apparent correlation between metabolic activity and transfer was observed. Additional experiments, however, suggested that there was no causal relationship between the two. When incubated in a sand microcosm containing root exudates, the metabolic activity of the bacteria increased while conjugal transfer ratios remained constant. Hence, contrary to the accepted view, root exudates and metabolic activity did not appear to be responsible for the stimulation of conjugal transfer in the rhizosphere. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.