Resistance and removal mechanisms of deep-sea Bacillus sp. A260 in mitigating Mn2+ and microplastic pollution.

Driven by rapid industrial development, manganese (Mn²⁺) and microplastic pollution pose serious threats to aquatic ecosystems and human neurological health, highlighting the urgent need for effective control strategies. Bioremediation has gained increasing attention in recent years owing to its high efficiency and environmentally friendly nature. In this study, we isolated a Mn²⁺-resistant strain, Bacillus sp. A260, from deep-sea cold seep sediments. This strain displayed exceptional tolerance to 300 mM Mn²⁺ and produced significant quantities of manganese carbonate (MnCO₃). Notably, elevated Mn²⁺ concentrations promoted biofilm formation by strain A260. Further mechanistic investigations revealed a coordinated regulatory network in Bacillus sp. A260, involving MntR-mediated Mn²⁺ homeostasis, YkoY/YceF-dependent Mn²⁺ efflux, and PerR/Fur-regulated Fe/Mn uptake. This network was accompanied by changes in energy metabolism, activation of oxidative stress response, and Spo0A-mediated biofilm synthesis, all of which contributed to the resilience of the strain under Mn²⁺ stress. In addition, Mn²⁺ induced biofilm formation enhanced the microplastic adsorption capacity of strain A260, enabling the simultaneous removal of Mn²⁺ and microplastics. Strain A260 achieved 97 % Mn²⁺ and 96 % microplastic removal at pH 7 and 37 ℃ within 14 days, and exhibited strong adaptability to pH and temperature variations. Thus, Bacillus sp. A260 serves as a robust model for studying microbial metal resistance and is a promising candidate for the simultaneous bioremediation of Mn²⁺ and microplastic contaminants in aquatic environments.