# Evaluation of Three Treatments for the Resource Utilization of Cephalosporin C Fermentation Residue

## TL;DR

This study evaluates three methods to treat cephalosporin C fermentation residue, finding that steam explosion is most effective in reducing antibiotics and resistance genes while preserving nitrogen.

## Contribution

The study introduces steam explosion as a novel and effective treatment for cephalosporin C fermentation residue.

## Key findings

- Steam explosion reduced residual cephalosporin C to 0 mg/kg and decreased antibiotic resistance genes by 62.2%.
- Steam explosion preserved 98.1% of nitrogen and reduced antimicrobial activity by 80.3%.
- LC/MS analysis showed steam explosion destroyed key antibiotic structures like the β-lactam ring.

## Abstract

In China, antibiotic fermentation residue has been listed as a “hazardous waste” due to its high residual concentrations of antibiotics. There are many ways to deal with antibiotic fermentation residue; however, effective methods are still lacking. In the present work, steam explosion (SE), thermal, and aerobic composting treatments were performed to investigate the resource utilization of cephalosporin C fermentation residue (CFR). The results show that 0 mg/kg, 50.2 mg/kg and 150.5 mg/kg cephalosporin C (CEPC) remained after the SE, composting, and thermal treatments. The total abundance of antibiotic resistance genes (ARGs) decreased by 62.2% and 47.2% after the SE and thermal treatments and increased by 1.4 times in the samples subjected to composting. Nitrogen analysis showed that the nitrogen loss (N loss) was only 1.9% in the SE-treated samples. The antibiotic inhibition zone was reduced by 80.3%, 71.2% and 40.8% in the samples subjected to SE, composting, and thermal treatments. LC/MS showed that the β-lactam ring and dihydrothiazine ring of CEPC were largely destroyed via SE. These results suggest that the SE treatment not only decreased the residual cephalosporin and ARG levels and antimicrobial activity but also preserved most of the nitrogen. SE is therefore a feasible treatment that can be used to deal with CFR.