The ecological and evolutionary implications of agricultural probiotics on the local soil microbiome

益生菌接种剂是向更可持续农业转变的主要工具。最明显的好处是豆类，如大豆，它与固氮菌-根瘤菌-形成联系，使它们能够从大气中获得氮，从而减少对碳密集型化肥的需求。为作物提供有效的根瘤菌菌株可以对产量产生重大影响，特别是当作物在其原生范围之外种植时，那里没有天然的根瘤菌伙伴。然而，向土壤中引入高密度的新细菌可能会对当地的微生物群落产生影响，而这些微生物群落在很大程度上是未被探索的。新细菌可能具有生态效应，例如冲刷掉局部多样性，或进化效应，例如通过水平基因转移将新基因引入常驻细菌。我们有机会在一个令人兴奋的时刻研究这些动态：英国正处于将新细菌广泛引入天真微生物群落的尖端。目前，大豆正在成为一种新的和可持续的作物，但它们的天然根瘤菌伙伴(大豆相关的慢生根瘤菌-SABS)在英国土壤中完全不存在。在这个项目中，我们将使用中生体实验结合尖端测序方法来研究SAB引入对英国土壤中当地微生物群的生态和进化影响。这名学生将与英国各地的大豆种植者接触，以确定采样地点，设计和进行温室实验，并开发分析方法。

Probiotic inoculants represent a major tool in the shift towards a more sustainable agriculture. The clearest benefits are seen in legumes, like Soya, which form associations with nitrogen fixing bacteria - rhizobia - allowing them to obtain nitrogen from the atmosphere and so reduce the need for carbon intensive fertilizers. Providing crops with effective rhizobia strains can have impressive impacts on yield, especially when crops are being grown outside of their native ranges where their natural rhizobial partners are absent. However, the introduction of high densities of novel bacteria into the soil is likely to have consequences for the local microbial community which are largely unexplored. Novel bacteria may have ecological effects, e.g. washing out of local diversity, or evolutionary effects, e.g. by introducing novel genes to resident bacteria through horizontal gene transfer.We have the opportunity to study these dynamics at an exciting moment: The UK is on the cusp of the widespread introduction of novel bacteria into a naïve microbial community. At present Soya is emerging as a novel - and sustainable - crop but their natural rhizobial partners (Soya-associated Bradyrhizobium - SABs) are entirely absent from UK soils. In this project we will use mesocosm experiments combined with cutting edge sequencing approaches to investigate the ecological and evolutionary effect of SAB introduction on the local microbiome in UK soils. The student will engage with Soya growers across the UK to identify sampling sites, design and conduct greenhouse experiments and develop analytical methods.