Insights into bacterial resistance to contaminants of emerging concerns and their biodegradation by marine bacteria

Contaminants of Emerging Concern (CECs) are human-made chemicals that remain unregulated. The continuous detection of CECs in aquatic ecosystems, due to their incomplete removal, emphasizes the importance of understanding their fate and impact on the environment and human health. The detrimental effects of CECs on marine eukaryotes are well documented in multiple studies. However, their impact on marine bacteria and their biodegradation by these organisms are not well understood. In this study, two marine bacteria, Priestia sp. 35 ODPABA G14 and Rhodococcus sp. 23 AHTN G14, previously isolated from submarine sediments, were used. These two strains were tested for their resistance as well as their capacity to degrade different classes of hydrophobic and hydrophilic CECs, including synthetic musks, UV filters, pesticides and pharmaceuticals. Both strains showed high resistance to all of the hydrophobic tested CECs even up to 500 mg L⁻¹. Only Ketoprofen was toxic to bacterial cells, particularly to Rhodococcus sp. starting at concentration as low as 4 mg L⁻¹. Furthermore, Priestia sp. and Rhodococcus sp. strains exhibited high biodegradation potential, especially for hydrophobic compounds. Although this may not apply to all pollutants, the data presented in this study suggest a positive correlation between marine bacterial resistance to CECs and their high biodegradation potentials.