Pseudomonas putida strain B2017 produced as technical grade active ingredient controls fungal and bacterial crop diseases

Biological control is emerging as a feasible alternative to chemical pesticides for the protection of crop plants. Pseudomonas putida shows enormous potential as biological control agent (BCA) not only because it is well reported to control a number of relevant crop diseases, but also because it has a short generation time, colonises plants and their environment, exerts its BCA activity through a range of different mechanisms, and promotes plant growth. Despite of these advantages no plant protection product based on P. putida is available in the market so far. In the present manuscript we describe the production of P. putida B2017, a novel biofungicide and biobactericide strain, at increasing scale – from laboratory (Erlenmeyer flasks) to pilot scale (125-L bioreactors) – as part of development process of a new commercial plant protection product. The technical grade active ingredient (TGAI) produced, regardless of the production scale, is as effective as the chemical reference against Fusarium oxysporum f.sp. radicis-lycopersici in tomato, Rhizoctonia solani in potato, Sclerotinia sclerotiorum in lettuce and Pectobacterium atrosepticum in potato. The TGAI titration obtained in 125-L bioreactors is high enough as to warrant effective TGAI concentration in a putative end-product even after typical viability losses expected during formulation. In summary, we hereby show that P. putida B2017 is a promising BCA not only because its efficacy against plant pathogens, but also because it can be produce at large scale.