The present invention refers to the strain CECT8538 of Pseudomonas putida and mutants thereof, and the use of said strain as a pesticide in controlling plant diseases caused by fungi and bacteria. Further aspects of the invention relate to methods for preparing pesticidal compositions comprising said strain. Finally, the invention relates to a method for controlling various plant diseases caused by fungi and bacteria in a plant, comprising treating the plant and/or seed thereof or substrate used for growing said plant with the strain CECT8538 of P. putida or a composition including it.