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

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.