Tetrabromobisphenol A (TBBPA; 4,4’-isopropylidenebis (2,6-dibromophenol)) is one of the most extensively used brominated flame retardants (BFRs), covering approximately 60% of the total worldwide usage [15]. It has been incorporated into numerous consumer products including plastics, textiles, and electronic circuit boards to protect materials against ignition [4]. TBBPA could act as hormones to interfere with the endocrine systems of organisms and humans due to its structural similarity to thyroxin [11]. However, it has been frequently detected in various environmental compartments and biota (ng/L-µg/L), and it is recognized as an important hazardous pollutant due to it may persist and bio-accumulate in the food chain [6, 10, 19, 35].
Physicochemical studies have shown the fate of TBBPA in the aquatic environment [2, 20] while biotransformation process is usually considered to play a major role in determining the fate of this compound in the natural environment. Several biotic studies focused mainly on reductive debromination of TBBPA to yield less brominated bisphenol A (BPA) under ananerobic conditions, and further removal of BPA was not occurred [29, 33]. However, TBBPA is probably long-term exposed to aerobic environment before partitioning into anaerobic conditions. So far, only a few published reports on aerobic biotransformation of TBBPA and mainly focused on freshwater sediment, river sediment, activated sludge, and soil [5, 16, 17]. Previous studies presented first evidence for aerobic TBBPA biodegradation in terrestrial settings, whereas there is limited study on degradation this compound and community-level changes in the coastal marine environment [7].
Coastal marine environments have received land-based source, river flow, stromwater runoff, sewage effluent and industrial wastewater [36]. Intertidal sediments are key transitional zones between terrestrial and aquatic environments, play an important role in biogeochemical cycles and ecosystem services [26]. It has been shown that TBBPA can be quite soluble under elevated pH [31]. On the other hand, a variety of industrial parks are located along the coastline in China and varying degree concentrations of BFRs have been detected in sediments were significantly associated with the urbanization and industrialization of the coastal zone [18]. Thus, if disposed improperly, BFRs in the recycling sites that adjacent to soil and river water could be finally transferred to the marine, which can exert potentially devastating effects on ecosystem structure and function. Wang et al. [34] found that Bacillus, Erythrobacter, Pseudomonas, and Rhodococcus were the main genus in a mangrove sediment. Jiang et al. [13] demonstrated that the predominant genus in TBBPA polluted mangrove species sediments were Anaerolineae, Geobacter, Pseudomonas, Flavobacterium, and Azoarcus. Thus far, the degradation of this compound in coastal environments remains obscure.
We hypothesis that the intertidal sediments that undergo flooding with seawater and exposure to the atmosphere between high and low tides should have significant impacts on TBBPA elimination. The main study aims to compare the removal of TBBPA in the intertidal sediment under different type of vegetation coverages and then track changes in bacterial community by using 16S rRNA gene based Illumina sequencing approach. This study will expand the understanding of the extent of whether indigenous marine microbes in the coastal marine environment are capable of biodegrading TBBPA and provide information on the fate of this compound.