Proteases de Bacillus licheniformis no controle de organismos de importância na saúde única

Abstract

The control of agricultural pests, plant-parasitic nematodes, and disease vectors still relies heavily on chemical pesticides, whose continuous use has favored the selection of resistant populations and caused significant environmental impacts. In this context, the search for sustainable biotechnological alternatives has driven research into microbial enzymes with nematicidal and insecticidal potential. This dissertation aimed to evaluate the efficacy of proteolytic formulations derived from Bacillus licheniformis in controlling different organisms of One Health importance. Four studies involving nematodes, insect pests, and mosquito vectors were conducted. In the first study, the in vitro activity of the HPF protease against the nematodes Panagrellus sp., Meloidogyne incognita, Haemonchus spp., and Trichostrongylus spp. was evaluated. The results demonstrated high nematicidal activity, with up to a 100% reduction in the survival of M. incognita and a significant decrease in the populations of the other nematode species, highlighting the enzyme's potential to degrade the cuticle and body structures of these organisms. In the second study, three commercial protease formulations (APP1500, HPP, and HPF) were evaluated for the control of M. incognita in vitro and under greenhouse conditions. The enzymes exhibited high proteolytic activity under different pH and temperature conditions. Under greenhouse conditions, the formulations promoted reductions of more than 80% in the number of nematode galls and eggs. The third study investigated the larvicidal activity of the HPF formulation against Aedes aegypti larvae. Mortality was dependent on both concentration and exposure time, reaching 100% after 72 h at a concentration of 1.5% (w/v). Morphological analyses revealed severe damage to larval tissues, including leakage of visceral contents, confirming the proteolytic activity of the formulation. Finally, the fourth study evaluated the insecticidal effects of the APP1500 and HPF formulations against Spodoptera frugiperda, one of the major agricultural pests. Larval mortality increased as a function of concentration and exposure time, with ingestion treatments proving more effective than topical application. In addition, signs of an insect immune response were observed, including cuticular darkening associated with the melanization process. Overall, the results demonstrate that proteases derived from B. licheniformis exhibit a broad spectrum of biological activity against organisms belonging to different taxonomic groups. The observed mechanisms suggest that these enzymes promote the degradation of essential protein structures, compromising the integrity of the cuticle, eggs, and internal tissues of the target organisms. Therefore, the evaluated formulations represent promising alternatives for the development of sustainable bioproducts for the management of plant-parasitic nematodes, medically important vectors, and agricultural pests.