Leão Pedro, Gueiros-Filho Frederico J, Bazylinski Dennis A, Lins Ulysses, Abreu Fernanda
Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
Instituto de Química, Universidade de São Paulo, São Paulo, SP, 05508-000, Brazil.
Antonie Van Leeuwenhoek. 2018 Nov;111(11):2213-2223. doi: 10.1007/s10482-018-1113-x. Epub 2018 Jun 18.
Magnetotactic bacteria, for the most part, are free-living, motile, unicellular prokaryotes that inhabit almost all marine and freshwater environments. One notable exception to the unicellular mode, however, are the magnetotactic multicellular prokaryotes. These morphologically unique prokaryotes (e.g., Candidatus Magnetoglobus multicellularis) are motile aggregates of 20-40 genetically identical, Gram-negative cells organised as a sphere (or ovoid in shape) and only motile as a unit. No specific close physical association between magnetotactic bacteria and non-magnetotactic microorganisms has ever been reported. Here, using culture-independent approaches, we show an unusual association between the spherical magnetotactic multicellular prokaryote Ca. Magnetoglobus multicellularis and Pseudoalteromonas species in environmental sediment and water samples collected from the Araruama Lagoon in Brazil. Cells of Pseudoalteromonas species were observed to be physically attached to the surface and, notably, even in the intercellular space of these spherical magnetotactic multicellular prokaryotes. An attempt to correlate the frequency of association between Pseudoalteromonas and magnetotactic multicellular prokaryotes with sediment depth was made but only a slight decrease in the number of Pseudoalteromonas cells per magnetotactic multicellular prokaryote was observed with increasing depth. Similar observations were made with magnetotactic multicellular prokaryotes from another Brazilian Lagoon (Rodrigo de Freitas) and the putative symbiont/parasite was detected. Although our results suggest some sort of specificity in the relationship between these prokaryotes, the precise nature of this association remains unclear.
趋磁细菌在很大程度上是自由生活、能运动的单细胞原核生物，几乎栖息于所有海洋和淡水环境中。然而，单细胞模式的一个显著例外是趋磁多细胞原核生物。这些形态独特的原核生物（如“候选趋磁球孢菌”）是由20 - 40个基因相同的革兰氏阴性细胞组成的能运动的聚集体，这些细胞组织成一个球体（或卵形），且仅作为一个整体运动。从未有过关于趋磁细菌与非趋磁微生物之间存在特定紧密物理关联的报道。在此，我们采用非培养方法，在从巴西阿拉鲁阿马泻湖采集的环境沉积物和水样中，发现了球形趋磁多细胞原核生物“候选趋磁球孢菌”与假交替单胞菌属物种之间的一种不同寻常的关联。观察到假交替单胞菌属的细胞附着在这些球形趋磁多细胞原核生物的表面，值得注意的是，甚至在其细胞间隙中也有。我们尝试将假交替单胞菌与趋磁多细胞原核生物之间的关联频率与沉积物深度相关联，但仅观察到随着深度增加，每个趋磁多细胞原核生物上假交替单胞菌细胞的数量略有减少。在来自巴西另一个泻湖（罗德里戈·德·弗雷塔斯泻湖）的趋磁多细胞原核生物中也有类似观察结果，并检测到了假定的共生体/寄生物。尽管我们的结果表明这些原核生物之间的关系存在某种特异性，但这种关联的确切性质仍不清楚。
