Aims

To evaluate the occurrence, the characterization and identity of nodulating bacteria in symbiosis with Mimosa spp. in the ultramafic massif of Barro Alto, Goiás state, Brazil.

Methods

Nodules from field grown M. somnians and M. claussenii were sampled for bacteria isolation and in situ detection using microscopy. Isolates were characterized for their nodulation capacity on M. pudica and common bean, and their tolerance to Ni in culture medium. Bacteria were also partially identified by their 16S rRNA gene sequences. In addition, recA, gyrB, nodC and nifH genes from five representative isolates were sequenced for phylogenetic studies.

Results

In situ detection indicated the exclusive presence of Paraburkholderia sp. within the nodules. This identification was confirmed for most of the isolates by the analysis of their 16S rRNA gene sequences. All isolates identified as Paraburkholderia sp. were able to effectively nodulate M. pudica, but those tested in common bean produced ineffective nodules. Inoculation tests showed that these bacteria improved M. pudica growth in the absence of nitrogen. None of the isolates showed Ni tolerance. The concatenated 16S rRNA, recA and gyrB, and the nodC and nifH genes sequences demonstrated that the five selected isolates were closely related to P. atlantica.

Conclusions

This is the first report of Paraburkholderia present in nodules from Mimosa plants naturally growing in ultramafic soils. These results suggest that this symbiosis may be a factor to be considered as part of programs to restore ultramafic soils in Barro Alto areas degraded by mining activity.

中文翻译：

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Paraburkholderia atlantica 是含羞草属的主要根瘤菌共生体。在巴西塞拉多生物群落的超镁铁质土壤中

目标

为了评估与含羞草共生的结瘤细菌的发生、特征和特性。在巴西戈亚斯州巴罗阿尔托的超镁铁质地块中。

方法

对来自田间生长的M. somnians和M. claussenii的结核取样进行细菌分离和使用显微镜进行原位检测。分离株的特征在于它们对M. pudica和菜豆的结瘤能力，以及它们对培养基中镍的耐受性。细菌也通过它们的 16S rRNA 基因序列进行了部分鉴定。此外，对来自五个代表性分离株的recA、gyrB、nodC和nifH基因进行了测序，用于系统发育研究。

结果

原位检测表明Paraburkholderia sp。结节内。通过分析它们的 16S rRNA 基因序列，大多数分离株的这种鉴定得到了证实。所有分离株均被鉴定为Paraburkholderia sp。能够有效地使M. pudica结瘤，但在普通豆中测试的那些产生无效的结节。接种试验表明，这些细菌在没有氮的情况下改善了M. pudica的生长。没有分离株表现出对镍的耐受性。串联的 16S rRNA、recA和gyrB，以及nodC和nifH基因序列表明，5个筛选出的分离株与大西洋大西洋杨密切相关。

结论

这是在超镁铁质土壤中自然生长的含羞草植物的结核中存在的Paraburkholderia的第一份报告。这些结果表明，这种共生关系可能是一个因素，可以作为恢复因采矿活动而退化的 Barro Alto 地区超镁铁质土壤的计划的一部分。