Evaluation of Raw Cheese as a Novel Source of Biofertilizer with a High Level of Biosecurity for Blueberry

Today's agriculture requires the search for new and modern tools in order to improve and expand the use of its crops and to increase their sustainability. The use of plant growth-promoting PGP bacteria (PGPB) is the target of much research and seems to be an ideal strategy as long as the strains are properly selected for this purpose. Among the bacteria, lactic acid bacteria (LAB) are considered a suitable alternative due to their high biosafety and mechanisms for promoting plant growth. In view of this, in this work we decided to isolate LAB with PGP capacity from raw milk cheese of the PDO "Serra da Estrela". A total of 88 strains with a high diversity and remarkable capacity to control food-borne and pathogenic microorganisms were isolated. In addition, most of them showed excellent capacities for phosphate solubilization and the production of indole-3-acetic acid and siderophores. Subsequently, we also studied their inoculation in blueberry seedlings. Among the isolates, strains QSE20, QSE62 and QSE79 showed the most remarkable ability to efficiently colonize the rhizosphere of this plant, improving root development and increasing the number of secondary roots.