Prospecção de bactérias produtoras de biossurfactantes em áreas de transição (portos)

Abstract

Biosurfactants, amphiphilic compounds produced by microorganisms, have attracted increasing interest due to their biodegradability, low toxicity, and effectiveness under diverse environmental conditions, making them promising alternatives to synthetic surfactants in remediation processes and industrial applications. This dissertation is structured into two complementary chapters. The first chapter presents a systematic review on the prospecting of biosurfactants in transitional ecosystems, such as mangroves, port areas, and coastal zones, with emphasis on their applications in bioremediation. Sixteen articles published between 2015 and 2025 were analyzed, selected from international databases (Scopus, Web of Science, and PubMed). The studies indicate a predominance of biosurfactants belonging to the glycolipid and lipopeptide classes, produced mainly by bacteria of the genera Pseudomonas, Bacillus, and Rhodococcus, as well as yeasts such as Candida and Starmerella. A growing trend toward the use of agro-industrial residues as substrates was also observed, reinforcing the alignment of these technologies with sustainability principles and the circular economy. The reported applications demonstrate high efficiency of biosurfactants in the solubilization and mobilization of pollutants, including hydrocarbons and heavy metals, highlighting their strategic role in the bioremediation of impacted transitional environments. In the second chapter, an experimental study was conducted to prospect biosurfactant-producing bacteria in port areas of the municipality of Piúma, Espírito Santo, Brazil, characterized by contamination from diesel oil. Sediment samples were collected from points of high vessel traffic, resulting in the isolation of seven bacterial strains. These isolates were cultivated in minimal salt medium (MSM), using diesel oil as the sole carbon source. The surfactant activity of the produced metabolites was evaluated using drop-collapse and oil-spreading tests, as well as the emulsification index (E24), employing diesel oil and gasoline as oily phases. The biosurfactants exhibited low emulsifying activity against diesel oil (E24 < 10%); however, they demonstrated moderate efficiency in the emulsification of gasoline, with indices reaching approximately 35% for some isolates, indicating greater affinity for light hydrocarbons. Taken together, the findings from the systematic review and the experimental study reinforce the potential of biosurfactants as valuable tools for the remediation of contaminated environments and highlight the importance of transitional ecosystems— such as mangroves and port areas—as reservoirs of microorganisms with biotechnological relevance. The integration of these approaches contributes to advancing knowledge on the microbial diversity involved in biosurfactant production, their applications, and the remaining challenges related to large-scale production and the economic feasibility of these bioproducts in environmental and industrial contexts.