Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstraße 7 B, D-38124 Braunschweig, Germany.
Institute for Biological Interfaces, Karlsruhe Institute of Technology, Germany.
Syst Appl Microbiol. 2018 Nov;41(6):544-554. doi: 10.1016/j.syapm.2018.08.012. Epub 2018 Sep 1.
Many marine Alphaproteobacteria of the Roseobacter group show a characteristic swim-or-stick lifestyle, for which motility is a crucial trait. Three phylogenetically distinct flagellar gene clusters (FGCs) have been identified in Rhodobacteraceae that have been named fla1, fla2 and fla3 according to their relative abundance. In addition to the flagellar-dependent swimming and swarming motility, pilus-dependent twitching mediates bacterial locomotion. Furthermore, filament independent modes of motility, namely gliding and sliding, have been described for various microorganisms. However, no mode of motility other than swimming has so far been described for roseobacters. In the present study, we investigated motility, distribution of flagellar systems and the phylogeny of 120 genome-sequenced Rhodobacteraceae. The phylogenetically broad taxon sampling that included 114 type strains revealed the presence of at least ten distinct clades that were statistically well supported. The investigation of the actual physiological capacity for swimming motility on soft agar plates showed that only about half of the 120 tested strains were motile under the tested conditions. Seven strains developed a conspicuous dendritic motility phenotype that was reminiscent of the swarming motility in Pseudomonas aeruginosa. The observed dendritic motility in two strains (i.e. Sulfitobacter pseudonitzschiae DSM 26842 and Roseovarius pacificus DSM 29589) was particularly surprising because they did not harbor any genes of the FGC. Accordingly, it was concluded that this form of dendritic motility was independent of a flagellum. A comparative genomics approach allowed a remarkable number of pilus-related candidate genes to be identified for this novel type of motility in Rhodobacteraceae.
许多海洋 Alpha 变形菌的玫瑰杆菌群表现出一种独特的游动或黏附生活方式，其中运动能力是一个关键特征。在红杆菌科中已经确定了三个在系统发育上不同的鞭毛基因簇 (FGC)，根据它们的相对丰度分别命名为 fla1、fla2 和 fla3。除了依赖于鞭毛的游动和群体游动运动之外，菌毛依赖性的抽动还介导细菌的运动。此外，各种微生物的滑动和滑行等丝状菌独立运动方式也有描述。然而，到目前为止，还没有描述过玫瑰杆菌的其他运动方式，除了游动。在本研究中，我们调查了运动性、鞭毛系统的分布以及 120 个基因组测序的红杆菌科的系统发育。包括 114 个模式菌株的广泛的系统发育分类群采样揭示了至少存在十个不同的支系，这些支系在统计学上得到了很好的支持。在软琼脂平板上调查实际的游泳运动能力表明，在测试条件下，只有大约一半的 120 个测试菌株具有运动能力。七种菌株表现出明显的树枝状运动表型，类似于铜绿假单胞菌的群体游动。在两种菌株（即 Sulfitobacter pseudonitzschiae DSM 26842 和 Roseovarius pacificus DSM 29589）中观察到的树枝状运动特别令人惊讶，因为它们没有任何 FGC 的基因。因此，得出的结论是，这种树枝状运动形式独立于鞭毛。比较基因组学方法允许为红杆菌科的这种新型运动方式鉴定大量与菌毛相关的候选基因。
