Testing Bdellovibrio As a Global Food Security Agents in Crops.

Bdellovibrio bacteriovorus HD100 is a small, Gram-negative, soil bacterium that naturally preys upon other Gram-negative bacteria to grow and reproduce, invading and killing their prey in the process. Natural prey species include a wide variety of soil-dwelling bacterial pathogens that infect agriculturally important plants, fungi and trees, including many species of Pseudomonas; some other prey species are commensals that have a beneficial effect on crop growth. Bdellovibriocould therefore be applied to crop surfaces, pre and post-harvest and to soils as a ‘food security agent’ against bacterial crop pathogens, but may have a complex effect on natural field soil microbiota and therefore crop growth.  I have been studying such crop surface and soil microbiotal effects during my doctoral studies.

We monitored the effects of Bdellovibrio bacteriovorus predatory activity on the surface of post-harvest button mushrooms when infected with Pseudomonas tolaasii, a ‘brown-blotch’ lesion-causing pathogen. Adding Bdellovibrio before or after administration of the P. tolaasii pathogen significantly improved brown blotch appearance on the mushroom surface, along with a reduction in P. tolaasii cell number recovered from the surface tissue.  Bdellovibrio attachment to P. tolaasii and infected-prey “bdelloplast” formation was visible on the mushroom surface in scanning electron microscope images.  Thus B. bacteriovorus kills pathogens in funga.

We have also tested the effects of adding Bdellovibrio bacteriovorus to natural field soil around crop plants, contained in pots. We report the effects of B. bacteriovorus HD100, in field soil, on crop plant height and other indicators of crop yield, when compared to a buffer control. We also present metagenomic analysis of soil microbiota with and without B. bacteriovorus present.

 Our mushroom work shows that Bdellovibrio is an effective food security agent, protecting against gram-negative pathogens post-harvest on mushrooms. The effect of Bdellovibrio application in different field soil types is currently being investigated.