Harnessing the microbiomes of Brassica vegetables for health issues.

Plant health is strongly connected with plants´ microbiome. In case of raw-eaten plants, the microbiome can also affect human health. To study potential impacts on health issues of both hosts, the microbiome composition of seven different Brassica vegetables, originating from different food processing pathways, was analyzed by a combined approach of amplicon sequencing, metagenomic mining and cultivation. All Brassica vegetables harbored a highly diverse microbiota as identified by 16S rRNA gene amplicon sequencing. The composition of the microbiota was found to be rather driven by the plant genotype than by the processing pathway. We characterized isolates with potential cancer-preventing properties by tracing myrosinase activity as well as isolates with biological control activity towards plant pathogens. We identified a novel strain with myrosinase activity and we found bacterial myrosinase genes to be enriched in rhizosphere and phyllosphere metagenomes of Brassica napus and Eruca sativa in comparison to the surrounding soil. Strains which were able to suppress plant pathogens were isolated from naturally processed vegetables and represent a substantial part (4.1%) of all vegetable microbiomes. Our results shed first light on the microbiome of edible plants and open the door to harnessing the Brassica microbiome for plant disease resistance and human health.