Vial Ludovic, Cuny Caroline, Gluchoff-Fiasson Katia, Comte Gilles, Oger Phil M, Faure Denis, Dessaux Yves, Bally René, Wisniewski-Dyé Florence
UMR-CNRS 5557 Ecologie Microbienne, Université Claude Bernard Lyon 1, Villeurbanne, France.
FEMS Microbiol Ecol. 2006 Nov;58(2):155-68. doi: 10.1111/j.1574-6941.2006.00153.x.
Forty Azospirillum strains were tested for their ability to synthesize N-acyl-homoserine lactones (AHLs). AHL production was detected for four strains belonging to the lipoferum species and isolated from a rice rhizosphere. AHL molecules were structurally identified for two strains: Azospirillum lipoferum TVV3 produces 3O,C(8)-HSL (N-3-oxo-octanoyl-homoserine-lactone), C(8)-HSL (N-3-octanoyl-homoserine-lactone), 3O,C(10)-HSL (N-3-oxo-decanoyl-homoserine-lactone), 3OH,C(10)-HSL (N-3-hydroxy-decanoyl-homoserine-lactone) and C(10)-HSL (N-3-decanoyl-homoserine-lactone), whereas A. lipoferum B518 produced 3O,C(6)-HSL (N-3-oxo-hexanoyl-homoserine-lactone), C(6)-HSL (N-3-hexanoyl-homoserine-lactone), 3O,C(8)-HSL, 3OH,C(8)-HSL and C(8)-HSL. Genes involved in AHL production were characterized for A. lipoferum TVV3 by generating a genomic library and complementing an AHL-deficient strain with sensor capabilities. Those genes, designated alpI and alpR, were found to belong to the luxI and luxR families, respectively. When cloned in a suitable heterologous host, alpI and alpR could direct the synthesis of the five cognate AHLs present in A. lipoferum TVV3. These two adjacent genes were found to be located on a 85 kb plasmid. Southern hybridization experiments with probes alpI/R indicated that genes involved in AHL production in the three other AHL-producing strains were not closely related to alpI and alpR. This study demonstrates that AHL-based quorum-sensing is not widespread among the genus Azospirillum and could be found only in some A. lipoferum strains.
对40株固氮螺菌菌株合成N-酰基高丝氨酸内酯（AHLs）的能力进行了测试。从水稻根际分离出的属于脂环固氮螺菌的4个菌株检测到AHL的产生。对两个菌株的AHL分子进行了结构鉴定：脂环固氮螺菌TVV3产生3O，C(8)-HSL（N-3-氧代辛酰基高丝氨酸内酯）、C(8)-HSL（N-3-辛酰基高丝氨酸内酯）、3O，C(10)-HSL（N-3-氧代癸酰基高丝氨酸内酯）、3OH，C(10)-HSL（N-3-羟基癸酰基高丝氨酸内酯）和C(10)-HSL（N-3-癸酰基高丝氨酸内酯），而脂环固氮螺菌B518产生3O，C(6)-HSL（N-3-氧代己酰基高丝氨酸内酯）、C(6)-HSL（N-3-己酰基高丝氨酸内酯）、3O，C(8)-HSL、3OH，C(8)-HSL和C(8)-HSL。通过构建基因组文库并用具有传感能力的AHL缺陷菌株进行互补，对脂环固氮螺菌TVV3中参与AHL产生的基因进行了表征。发现这些分别命名为alpI和alpR的基因分别属于luxI和luxR家族。当克隆到合适的异源宿主中时，alpI和alpR可以指导脂环固氮螺菌TVV3中存在的5种同源AHL的合成。发现这两个相邻基因位于一个85 kb的质粒上。用alpI/R探针进行的Southern杂交实验表明，其他3个产生AHL的菌株中参与AHL产生的基因与alpI和alpR没有密切关系。这项研究表明，基于AHL的群体感应在固氮螺菌属中并不普遍，仅在一些脂环固氮螺菌菌株中存在。
