Análise genômica de bactérias com capacidade de degradar combustíveis fósseis, isoladas do Rio Negro, Manaus-Am

Abstract

Hydrocarbon pollution is recognized as one of the major environmental problems of recent decades, resulting from oil and petroleum derivative spills. In the Amazon region, the risk is exacerbated by the high consumption of diesel oil used in vessels, which increases the contamination of aquatic and terrestrial ecosystems. In this context, bioremediation emerges as a promising alternative for mitigating these impacts. Previous studies conducted with bacterial consortia isolated near the Ceasa port (Manaus-AM) demonstrated the efficiency of consortium A3 in hydrocarbon degradation, achieving rates above 70% in just seven days. This research focused on the identification and functional characterization of three bacterial strains isolated from contaminated environments: Acinetobacter seifertii (313), Achromobacter xylosoxidans (314), and Pseudomonas sp. (316). For strain 316, belonging to the Pseudomonas genus, phylogenomic analysis indicated low ANI identity and dDDH values below 70% compared to the closest type species, suggesting it may represent a potential new Pseudomonas species. Through genome assembly and annotation, genes associated with the degradation of aliphatic and aromatic hydrocarbons were identified, particularly monooxygenases such as alkB, ladA, almA, and CYP450. These enzymes participate in the initial stages of hydrocarbon oxidation, facilitating their entry into β-oxidation pathways and subsequent mineralization. The strains were experimentally evaluated for their hydrocarbon-degrading abilities using two complementary methods: the colorimetric assay with 2,6-dichlorophenol-indophenol (DCPIP), and gas chromatography–mass spectrometry (GC-MS), which quantifies the specific degradation of n-alkanes present in diesel. The results showed that Acinetobacter seifertii (313) exhibited superior performance in both tests, degrading between 76% and 92% of alkanes (C11–C26), outperforming the bacterial consortium A3 and the pure cultures 314 and 316. Strain 314 achieved more modest degradation rates, ranging from 10% to 52%, while strain 316 displayed intermediate performance, varying between 12% and 53%.