Study on the effect of magnetite on biofilm yield,EPS composition,and adsorption function
Magnetite is widely present in natural environments,and its contact with biofilms can affect the extracellular polymeric substances(EPS)in them.However,the effects of different concentrations and sizes of magnetite on EPS secretion and composition have not been reported.This study investigated the effects of adding varying concentrations and particle sizes of magnetite to the biofilm formation process of Bacillus amyloliquefaciens DT at different time on the biofilm yield,morphology,EPS secretion and composition,as well as its adsorption performance and mechanism for BDE-47.Results indicated that magnetite addition increased biofilm yield,altered biofilm morphology,and promoted the secretion of dissolved EPS,with the highest secretion reaching 410 mg·L-1.Notably,the addition of 1 g·L-1 50 nm magnetite resulted in the highest protein secretion in EPS.The addition time of magnetite affected the biofilm yield.Adding magnetite with different concentrations before bacterial solution settling had a notable impact on biofilm formation,and magnetite with small particle size was more likely to promote biofilm formation.Results of three-dimensional fluorescence spectroscopy and Fourier-transform infrared spectroscopy indicated that magnetite addition promoted the production of protein-like substances in biofilm.The adsorption experiments of specific biofilms on BDE-47 demonstrated that the addition of 1 g·L-1 50 nm magnetite yielded the highest adsorption capacity,and protein in the biofilm played a major role in the adsorption process.This study elucidates the influence and mechanism of magnetite on the composition and function of biofilm,which can provide theoretical basis for the preparation of biofilm with high adsorption properties.
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