Towards Nutrition-Sensitive Agriculture: an evaluation of biocontrol effects, nutritional value, and ecological impact of bacterial inoculants

Nutrition-Sensitive Agriculture (NSA) is a novel concept in agriculture that does not consider only yield, but also nutritional value of the food, sustainability of the production, and the ecological impact of agricultural practices. In accordance with its goals, NSA would benefit from applying microbial-based products as they are deemed more sustainable than their synthetic counterparts.This study aims to characterize the effect of 3 plant-beneficial bacterial strains (Paenibacillus pasadenensis strain R16, Pseudomonas syringae strain 260-02, Bacillus amyloliquefaciens strain CC2) on the nutritional and texture quality of romaine lettuce plants (Lactuca sativa) and in containing pathogens in controlled conditions (greenhouse). The pathogens used in the trials are Rhizoctonia solani and Pythium ultimum. The obtained results indicate that strain R16 had a significant ability to reduce symptoms caused by both analyzed pathogens, while the other two strains showed a less efficient biocontrol ability.Indices of the nutritional quality (photochemical activity of photosystem II, content in phenols, carotenoids and chlorophyll) were largely unaffected by the treatments, indicating that the product was equivalent to that obtained without using the bacteria, while the texture of the leaves benefits from the biocontrol treatments.The ecological impact was evaluated by characterizing the bulk soil, rhizosphere, and root microbiota in the presence or absence of the inoculants.The composition of the microbiota was radically different in the rhizosphere and the root endosphere among treatments, but the bulk soil remained practically unchanged, indicating that the use of these treatments did not have a large-scale ecological effect.