Mineração genômica e identificação de moléculas com potencial biotecnológico da microbiota amazônica

Abstract

The Amazon, with its vast biodiversity, harbors a complex network of ecosystems interconnected by rivers such as the Negro and Solimões. This unique dynamic favors the emergence and diversification of microbial lineages, rendering the region a hotspot for the discovery of innovative biological solutions. Within this context, this thesis investigated the biotechnological potential of 36 bacteria isolated from Amazonian river sediments, focusing on applications in phytopathogen biocontrol and plant growth promotion. The bacterial isolates were evaluated in vitro against agriculturally significant phytopathogens, including Corynespora cassiicola, Colletotrichum siamense, Rhizoctonia solani, and Ralstonia solanacearum. This initial screening gave rise to two main chapters: the first investigates the biocontrol of R. solanacearum, while the second examines the genomic potential and agricultural applications of Alcaligenes nematophilus SOL 109. In Chapter 1, three isolates - Priestia aryabhattai RN 11, Streptomyces sp. RN 24, and Kitasatospora sp. SOL 195 - demonstrated remarkable efficacy against R. solanacearum, with in vitro inhibition of 87-100%, reduction of disease incidence by 40-90% in tomato seedlings, and promotion of plant growth. Phylogenomic analyses based on ANI and dDDH revealed that RN 11 belongs to the species Priestia aryabhattai (ANI: 98.61%, dDDH: 88.3%), while RN 24 and SOL 195 presented values below the cut-off points for new species, potentially representing novel species within the genera Streptomyces and Kitasatospora, respectively. Chapter 2 elucidates the multifaceted potential of A. nematophilus SOL 109, demonstrating in vitro inhibition ranging from 74 to 93% against phytopathogenic fungi. Under greenhouse conditions, evaluations indicate that the SOL 109 effectively controlled the pathogen R. solani and promoted growth in tomato plants. Genomic and chemical analyses of SOL 109 identified unique and shared biosynthetic gene clusters (BGCs) within the genus Alcaligenes, genes conferring resistance to antibiotics and heavy metals, and metabolites with antimicrobial properties. The results of this thesis highlight the unexplored potential of Amazonian aquatic microorganisms, revealing new actinobacterial species (RN 24 and SOL 195) and reporting for the first time the occurrence of A. nematophilus in Brazil. This study significantly contributes to the development of sustainable plant disease management strategies, offers valuable insights into the secondary metabolism of the genus Alcaligenes, and opens new perspectives for biotechnological applications in agriculture, reinforcing the importance of conservation and study of Amazonian microbial biodiversity.