Desenvolvimento de bioinoculantes para promoção de crescimento e controle de fitopatógenos de interesse agrícola com base em espécies de Streptomyces e Bacillus isolados de rios amazônicos

Abstract

This thesis aimed to investigate the biotechnological potential of two Streptomyces and three Bacillus strains isolated from Amazonian sediments for the development of bioinoculants with applications in phytopathogen control and plant growth promotion. The study was structured into three complementary chapters. In Chapter I, two Streptomyces strains (APUR 32.5 and MPUR 40.3) were evaluated for their biocontrol potential against anthracnose caused by Colletotrichum scovillei in peppers (Capsicum chinense), as well as their ability to stimulate plant growth. Both strains exhibited significant antifungal activity in vitro and in vivo, in addition to promoting root growth. Furthermore, the strains expressed hydrolytic enzymes, solubilized phosphates, and produced siderophores, demonstrating promising characteristics for use as multifunctional bioinoculants. Chapter II provided an in-depth genomic and chemical characterization of these Streptomyces strains. Phylogenomic analysis indicated that APUR 32.5 represents a potential new species. Genome mining revealed biosynthetic gene clusters (BGCs) related to the production of bioactive metabolites, which was corroborated by metabolomic analyses and antifungal activity assays of the extracts. The integration of genomic and chemical data allowed for the association of BGCs with the detected bioactive compounds, reinforcing the biotechnological potential of these strains. In Chapter III, three Bacillus strains (MPUR 33.1, MPUR 35.2, and MPUR 44.1) were characterized through phylogeny, biosynthetic gene prediction, and antifungal activity. The analyses demonstrated that these strains possess a wide diversity of genes related to the production of secondary metabolites and hydrolytic enzymes. The results obtained in this thesis highlight the potential of Amazonian microorganisms as promising sources for the development of sustainable bio-inputs, contributing to the reduction of chemical pesticide use and the adoption of sustainable agricultural practices.