Marine sediments microbes degrade a limited repertoire of organic UV filters

Understanding the processes that organic UV filters undergo in coastal and marine environments is crucial for assessing their long-term environmental risks. One key process is degradation by microorganisms in sediments. This study aimed to determine whether coastal marine sediments harbor microorganisms capable of degrading organic UV filters. Sediment from Toulon Harbor was tested for its degradation potential with respect to 12 different organic UV filters. Sediment microcosms showed degradation activity towards benzophenone-3 (BP3), 2-ethylhexyl salicylate (ES), and homosalate (HS) after 12 days. However, no degradation was observed for butyl methoxydibenzoylmethane (BM), octocrylene (OC), diethylamino hydroxybenzoyl hexyl benzoate (DHHB), drometrizole trisiloxane (DTS), phenylene bis-diphenyltriazine (TriAsorB), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), diethylhexyl butamido triazone (DBT), or ethylhexyl triazone (ET), even after 100 days of incubation. Two degrading strains were isolated from the microcosms: a Rhodococcus strain degrading ES and a Microbacterium strain capable of degrading HS. Despite substantial efforts, the microorganism thought to be responsible for BP3 degradation could not be isolated. This work demonstrates that microorganisms in coastal sediments can degrade a limited range of organic UV filters.