Bisphenol A degradation by halotolerant Bacillus HQ-51-Ba from deep sea environment and its metabolic pathway

Bisphenol A (BPA), as an endocrine disruptor, has estrogenic activity and disrupts the endocrine systems of humans and animals, leading to various health problems. Bacterial degradation is considered to be a cost effective and environmentally friendly method for BPA degradation compared to other treatment methods. HQ-51-Ba, was isolated from sediment of the deep ocean hydrothermal region in the Atlantic Ocean, and showed high degradation capacity for BPA at salinity environment. By analyzing the morphology and 16S rRNA sequence results, HQ-51-Ba was identified as Bacillus sp. Additionally, the gene of spore coat protein A (CotA) was found in complete genome sequence, which showed laccase activity for BPA degradation. Compared to other BPA-degrading bacteria, HQ-51-Ba exhibits superior viability and reproductive capacity at 7 % salinity. Under optimal conditions, it achieved complete degradation of BPA (10 mg/L) within 11 h. The functional enzyme responsible for BPA degradation was validated as intracellular. Identification of five key intermediates enabled the proposal of a BPA degradation pathway for HQ-51-Ba. Notably, intermediates 4-hydroxybenzoic acid (HBA) and 4-hydroxyacetophenone (HAP) demonstrate lower toxicity than BPA. The results of this study not only screened a salt tolerant strain of BPA degrading bacteria, but also provided a promising approach for the treatment of BPA pollution in saline wastewater. • A strain of salt-tolerant bacteria, HQ-51-Ba was isolated from deep sea. • HQ-51-Ba showed strong vitality and reproductive ability at a salinity of 7 %. • HQ-51-Ba completely degrades 10 mg/L BPA within 11 h under optimal conditions. • Five intermediates identified enabled a proposed BPA degradation pathway for HQ-51-Ba. • The toxicity of intermediate products HBA and HAP is lower than that of BPA.