Monitoramento de ambientes marinhos contaminados com hidrocarbonetos aromáticos de petróleo através de métodos moleculares

Abstract

The global demand for energy sustains frequent and intense activity in the oil industry, with offshore oil exploration being a common practice. The toxic, mutagenic, and carcinogenic potential of hydrocarbons, the main constituents of petroleum, makes marine biodiversity vulnerable to accidental spills, which can affect humans through the food chain or by reaching coastal zones. Continuous monitoring of marine environments represents an interesting strategy for the early detection of contamination, enabling rapid intervention to prevent short- and long-term catastrophic effects caused by the contamination of oceans by petroleum hydrocarbons. This study aimed to identify bacterial groups with the potential to indicate petroleum hydrocarbon contamination in marine environments via molecular approaches. To achieve this goal, four main experiments were conducted: (1) isolation and characterization of marine naphthalene-degrading strains; (2) evaluation of the modulation of marine bacterial communities exposed to different types of hydrocarbons (aliphatic, monocyclic aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAH), a synthetic mixture (MIX), and crude oil (OL)); (3) assessment of the impact of exposure time on microbial community dynamics in seawater; and (4) investigation of bacterial group occurrence across various beaches in the state of Rio de Janeiro before and after contamination with naphthalene. The first experiment was based on culture-dependent techniques, whereas the other experiments relied on 16S rRNA gene sequencing. The results revealed that both contaminant type and exposure time influenced the composition, structure, and succession dynamics of the bacterial communities. Compared with individual compounds, complex mixtures, such as crude oil, promoted greater diversity. Several bacterial genera exhibited specific responses to different hydrocarbons, and five groups were considered suitable for indicating contamination (target genera 1, 2, 3, 4, and 5, coded due to the intention to file a patent application). The selection of potential bioindicators was based on different criteria, including the frequency of occurrence, consistent enrichment in the presence of contaminants, and functional evidence from the literature related to the metabolic potential for degrading petroleum hydrocarbons. These groups consistently responded to contamination and were frequently detected in more than 37 sampling events across distinct geographic regions, environmental conditions, and experimental settings. Quantitative PCR (qPCR) has been proposed as a promising tool for the rapid and sensitive detection of the enrichment of these bacterial groups in marine environments, with potential applications in biomonitoring strategies. This approach is expected to contribute to the development of a broadly applicable and continuously usable tool for monitoring aquatic environments and enabling early detection of hydrocarbon contamination. Environmental monitoring remains essential for early warning, containment, and effective support of remediation practices.