Effects of Paenibacillus polymyxa inoculation on below-ground nematode communities and plant growth.

Paenibacillus polymyxa has been shown to have great potential as a bio-fertiliser and biocontrol agent, however information regarding its effect on below-ground biota when used as a soil additive is scarce. Below-ground biota provide vital services to boost plant performance and thus knowledge regarding their response to bio-fertiliser and biocontrol agents is critical for future crop management. Here, we extracted below-ground nematode (N) and microbial communities (M) and reassembled them in presence and absence of P. polymyxa soil inoculation (P). We then assessed the impacts of each of the three components, individually and in combination, on nematode community structure and plant growth. The main pattern was a gradual shift in the below-ground nematode community from those with increased abundances of omnivorous and plant parasitic nematodes towards those with increased abundances of predatory nematodes along the treatment gradient from N, to N,M to N,P to N,M,P. This shift from increased abundances of omnivores and plant parasitic nematodes to increased abundances of predatory nematodes was significantly positively correlated with plant growth. In conclusion, our study demonstrates for the first time that inoculation of soil with P. polymyxa changes the below-ground nematode community resulting in significant changes to plant growth. [ABSTRACT FROM AUTHOR]