Efficiency of benthic diatom-associated bacteria in the removal of benzo(a)pyrene and fluoranthene

Oumayma Kahla (1) , Sondes Melliti Ben Garali (1) , Fatma Karray (2) , Manel Ben Abdallah (3) , Najwa Kallel (2) , Najla Mhiri (3) , Hatem Zaghden (2) , Badreddine Barhoumi (4) , Olivier Pringault (5) , Marianne Quemeneur (5) , Marc Tedetti (5) , Sami Sayadi (6) , Asma Sakka Hlaili (1)

1 UCAR - Université de Carthage (Tunisie)
2 CBS - Centre de Biotechnologie de Sfax
3 Laboratoire des Bioprocédés Environnementaux, LMI COSYS-Med
4 EPOC - Environnements et Paléoenvironnements OCéaniques
5 MIO - Institut méditerranéen d'océanologie
6 Laboratoire des Bioprocédés Environnementaux

We investigated the efficiency of a benthic diatom-associated bacteria in removing benzo(a)pyrene (BaP) and fluoranthene (Flt). The diatom, isolated from a PAH-contaminated sediment of the Bizerte Lagoon (Tunisia), was exposed in axenic and non-axenic cultures to PAHs over 7 days. The diversity of the associated bacteria, both attached (AB) and free-living bacteria (FB), was analyzed by the 16S rRNA amplicon sequencing. The diatom, which maintained continuous growth under PAH treatments, was able to accumulate BaP and Flt, with different efficiencies between axenic and non-axenic cultures. Biodegradation, which constituted the main process for PAH elimination, was enhanced in the presence of bacteria, indicating the co-metabolic synergy of microalgae and associated bacteria in removing BaP and Flt. Diatom and bacteria showed different capacities in the degradation of BaP and Flt. Nitzschia sp. harbored bacterial communities with a distinct composition between attached and free-living bacteria. The AB fraction exhibited higher diversity and abundance relative to FB, while the FB fraction contained genera with the known ability of PAH degradation, such as Marivita, Erythrobacter, and Alcaligenes. Moreover, strains of Staphylococcus and Micrococcus, isolated from the FB community, showed the capacity to grow in the presence of crude oil. These results suggest that a “benthic Nitzschia sp.-associated hydrocarbon-degrading bacteria” consortium can be applied in the bioremediation of PAH-contaminated sites.

Mots clés: PAH accumulation; PAH biodegradation; Bizerte; Lagoon; Nitzschia sp. phycosphere; Hydrocarbon-degrading bacteria

Domaines: Océan, Atmosphère

Oumayma Kahla, Sondes Melliti Ben Garali, Fatma Karray, Manel Ben Abdallah, Najwa Kallel, et al.. Efficiency of benthic diatom-associated bacteria in the removal of benzo(a)pyrene and fluoranthene. Science of the Total Environment, 2021, 751, pp.141399. ⟨10.1016/j.scitotenv.2020.141399⟩. ⟨hal-02925530⟩