Degradation of Microplastics by Soil Bacterium Bacillus Subtilis in Combination with Mcnf Micromotor

Abstract

Microplastics possess high durability and a large surface area, facilitating their adhesion to various pollutants like heavy metal ions and organic contaminants, posing a significant threat to human health. Conventional physical and chemical degradation methods are ineffective due to the resilient nature of microplastics. Although microbial degradation is possible, it is slow. This research proposes the development of an H2O2 self-propelled micromotor utilizing fly ash, in conjunction with Bacillus subtilis, to degrade microplastics. The MCNF micromotor, characterized by an asymmetric shape, demonstrates a direct relationship between its trajectory length and speed of movement with the concentration of H2O2. Under visible light exposure, the micromotor exhibits efficient catalytic degradation capabilities. At a 2% H2O2 concentration, the micromotor induces deformation and damage to microplastics through Fenton oxidation. Importantly, the MCNF micromotor does not adversely affect the growth pattern of soil bacteriophage B. shortum or laccase (Lac) and peroxidase (POD) activities. Following Fenton pretreatment with the MCNF micromotor and H2O2, polystyrene microplastics undergo biodegradation, achieving a 60% degradation rate within 24 days. Additionally, the biological respiration process generates H2O2, and the direct introduction of MCNF micromotors enhances the biodegradation process, resulting in a 66% degradation rate of polyethylene within 50 days. Compared to the degradation efficiency of microplastics by Bacillus subtilis alone, the combined approach increases the degradation rate of polystyrene by 40% and polyethylene by 24%. This innovative method offers a promising avenue for environmentally friendly and effective microplastic degradation, with broad potential applications.

Keywords: microplastics, Biodegradation, micromotor, Fenton oxidation