Identification and biological screening in the search for antimicrobial agents produced by Actinobacteria against citrus canker

Abstract

Citrus cancer (Xanthomonas citri subsp. Citri, Xcc) is a phytopathology that occurs endemically in the main citrus regions in Brazil and its impact on orchards can result in significant productivity and economic losses. The disease has no cure and chemical control with cupric pesticides is the main measure used by producers to prevent the disease from entering the orchards. However, continued use of copper has raised concerns due to impacts related to human health and the ecosystem, food security, induction of resistance mechanisms by the Xcc bacterium and the adverse effects caused on citrus plants. The existence of environmentally friendly and effective products against citrus canker would reduce and/or replace the use of copper in the field. In this sense, biological control agents, especially microorganisms, represent promising alternatives to the use of chemical pesticides in agriculture. Therefore, the proposal of this project is the development of an efficient and environmentally safe agricultural biodefensive for a more sustainable management of citrus canker as an alternative to copper using actinobacteria as a biological agent. Actinobacteria are potential microorganisms for the search of antimicrobial agentes due to their intrinsic ability to produce secondary bioactive metabolites, especially antibiotics. In Brazil, there are no commercial biodefensives registered for citrus canker produced from actinobacteria. In Phase 1 of the project, it was possible to identify different actinobacteria isolates with a potent protective effect against citrus canker through in vitro and in vivo tests on Pera orange seedlings, proving the technical and scientific feasibility of the proposal. With the execution of Phase 2, we aim to develop our product on a pilot scale with aiming the commercialization of a new biodefensive product in the national market. For this, we will carry out the Scale-up of the productive scale; develop a formulation to optimize the product's effectiveness in the field, facilitate application, prolong stability and shelf life for commercialization and evaluate the efficiency of the product formulated in the field. Reaching these objectives, at the end of this project we will have the prototype of the biodefensive produced with actinobacterial assets duly standardized. In citrus production, Brazilian orange production is the largest in the world and accounts for more than 60% of the total juice produced and 80% of the international market, which is one of the main value chains of Brazilian agribusiness. With the development of biodefensives for the control of citrus canker, Actinobac will contribute to minimize losses and make Brazilian citrus culture more profitable and sustainable. (AU)