Effects of microplastics on the high-risk antibiotic resistance genes in different layer of membrane composting

Area of Science:

• Environmental Science
• Microbiology
• Agricultural Science

Background:

• Semipermeable membrane composting is used for poultry manure.
• Microplastic (MP) contamination is present in animal manure.
• Antibiotic resistance genes (ARGs) are a public health concern.

Purpose of the Study:

• To investigate the impact of microplastics (MPs) on high-risk antibiotic resistance genes (ARGs) during poultry manure composting.
• To analyze ARG levels in different layers of composting piles with and without MPs.

Main Methods:

• Composting experiments were conducted with and without MPs.
• High-risk ARGs (mcr-1, blaNDM-1, tetX) were quantified in different composting layers.
• Bacterial community composition associated with ARGs was analyzed.

Main Results:

• MPs significantly enhanced the removal of mcr-1 and blaNDM-1 (>99.50%) during the megathermal composting phase.
• MPs increased the growth rate of tetX in the middle and bottom layers compared to the control.
• MPs altered ARG-associated bacterial genera abundance, reducing overall ARG levels during the megathermal phase but increasing tetX during cooling.

Conclusions:

• Microplastics influence the fate of high-risk ARGs differently during composting phases.
• MPs can enhance the removal of some ARGs while promoting the proliferation of others.
• The bottom layer of compost piles with MPs poses a higher risk due to increased ARG host bacteria abundance.