Responses of Phragmites communis and its rhizosphere bacteria to different exposure sequences of molybdenum disulfide and levofloxacin

Abstract

The effect of the molybdenum disulfide (MoS₂)/levofloxacin (LVF) co-exposure was explored on Phragmites communis and rhizosphere soil bacterial communities. The sequence of MoS₂/LVF exposure and the different MoS₂ dosages (10 mg/kg and 100 mg/kg) contributed to different degrees of effect on the plant after 42 days of exposure. The treatment with priority addition of low dosage MoS₂ significantly ameliorated P. communis growth, with root length growing up to 532.22 ± 46.29 cm compared to the sole LVF stress (200.04 ± 29.13 cm). Besides, MoS₂ served as an alleviator and reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in P. communis under LVF stress, and activated bacteria in rhizosphere soil. These rhizosphere soil microbes assisted in mitigating toxic pollution in the soil and inducing plant resistance to external stress, such as bacteria genera Bacillus, Microbacterium, Flavihumibacter and altererythrobacter. Potential functional profiling of bacterial community indicated the addition of MoS₂ contributed to relieve the reduction in functional genes associated with amino acid metabolism and the debilitation of gram_negative and aerobic phenotypic traits caused by LVF stress. This finding reveals the effect of different exposure sequences of MoS₂ nanoparticles and antibiotic for plant-soil systems.

Keywords: Exposure sequence; MoS(2); Phragmites communis; levofloxacin.