Microcolonies, quorum sensing and cytotoxicity determine the survival of Pseudomonas aeruginosa biofilms exposed to protozoan grazing
Microcolonies, quorum sensing and cytotoxicity determine the survival of Pseudomonas aeruginosa biofilms exposed to protozoan grazing
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DOI：
10.1111/j.1462-2920.2004.00556.x
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发表时间：
2004-03-01
影响因子：
5.1
通讯作者：
Kjelleberg, S
中科院分区：
文献类型：
--
作者：
Matz, C;Bergfeld, T;Kjelleberg, S
本研究基于条件致病菌铜绿假单胞菌生物膜成功适应原生动物放牧的假设。我们测试了铜绿假单胞菌野生型和在生物膜发育的结构和调控特征方面发生遗传改变的菌株，以响应常见的表面摄食鞭毛虫鼻鼻状喙单胞菌。野生型的早期生物膜显示在鞭毛虫存在下形成抗放牧的小菌落，而没有捕食者的生物膜是未分化的。在群体感应突变体（lasR和rhlR/lasR）的生物膜上放牧也导致小菌落的形成，然而，与野生型相比，其数量和大小较低。与野生型相比，缺乏IV型皮利的突变细胞形成的小菌落少得多，而鞭毛缺陷细胞则没有形成小菌落。藻酸盐高产菌株PDO 300开发了更大的小菌落放牧。这些观察结果表明，在早期生物膜和参与鞭毛，IV型皮利的群体感应的作用，和藻酸盐在放牧的存在下，在微菌落形成。野生型成熟生物膜对鞭毛虫R.纳苏塔。rhlR/lasR突变体生物膜上的鞭毛虫的快速生长表明群体感应在致死因子的上调和晚期生物膜的放牧保护中起关键作用。小菌落的形成和毒素的产生都是铜绿假单胞菌生物膜抵抗原生动物放牧并在环境中持续存在的有效机制。
This study was based on the hypothesis that biofilms of the opportunistic pathogen Pseudomonas aeruginosa are successfully adapted to situations of protozoan grazing. We tested P. aeruginosa wild type and strains that were genetically altered, in structural and regulatory features of biofilm development, in response to the common surface-feeding flagellate Rhynchomonas nasuta. Early biofilms of the wild type showed the formation of grazing resistant microcolonies in the presence of the flagellate, whereas biofilms without the predator were undifferentiated. Grazing on biofilms of quorum sensing mutants (lasR and rhlR/lasR) also resulted in the formation of microcolonies, however, in lower numbers and size compared to the wild type. Considerably fewer microcolonies than the wild type were formed by mutant cells lacking type IV pili, whereas no microcolonies were formed by flagella-deficient cells. The alginate-overproducing strain PDO300 developed larger microcolonies in response to grazing. These observations suggest a role of quorum sensing in early biofilms and involvement of flagella, type IV pili, and alginate in microcolony formation in the presence of grazing. More mature biofilms of the wild type exhibited acute toxicity to the flagellate R. nasuta. Rapid growth of the flagellate on rhlR/lasR mutant biofilms indicated a key role of quorum sensing in the upregulation of lethal factors and in grazing protection of late biofilms. Both the formation of microcolonies and the production of toxins are effective mechanisms that may allow P. aeruginosa biofilms to resist protozoan grazing and to persist in the environment.