## 2 The Degradation of Antibiotics in the Natural Environment
### Biodegradation
The DIRB-driven Bio-Fenton process utilizes DIRB to reduce Fe\({}^{3+}\) to Fe\({}^{2+}\) through electron transfer, thereby enhancing the traditional Fenton reaction. DIRB also produces H\({}_{2}\)O\({}_{2}\) as a by-product of its metabolic activity, which participates in the generation of \(\bullet\)OH, thus degrading organic pollutants, including antibiotics [45]. However, most isolated strains have a single function and cannot adapt to real environments. In actual antibiotic degradation, high-diversity microbial communities can synergistically degrade antibiotics through various metabolic pathways (such as oxidation, reduction, and hydrolysis), achieving a higher degradation effect than single strains. Currently, the use of microbial communities to degrade fluoroquinolone antibiotics has been practically applied; for example, the microbial community in water filters can degrade ciprofloxacin in the water environment, achieving a removal rate of 89% after 28 days. In the degrading bacterial community, strains of the genera Rhizobium and Bacillus dominate [46]. The mixed microbial community AMQD4, composed of Providencia vermicola, Brevundimonas diminuta, etc., can degrade 56.8% of gentamicin (GEN), which is significantly higher than the degradation efficiency of single strains [47]. The community containing sulfate-reducing bacteria can degrade 84.2% of sulfamethoxazole, while the degradation efficiency of single strains is usually lower [48]. In recent years, research has revealed the potential risks of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) carrying ARGs in the microbial degradation process. As a new class of pollutants, ARGs can replicate within microorganisms and be passed on to offspring through vertical transfer; they can also spread between different species mediated by mobile genetic elements (MGEs), facilitating gene transfer among bacterial communities [49]. What is even more concerning is that ARGs can migrate between different media and even transfer into the food web, posing a threat to ecological safety and human health [50]. Research has shown that antibiotic-resistant bacteria in drinking water can enter the human body through oral ingestion. Although diseases may not occur in the short term, infections can happen when the bacteria accumulate to a certain level and the body's immune system is weakened [51]. In 2010, the superbug containing the NDM-1 gene was first discovered in the human body in New Delhi, India. This superbug can develop resistance to multiple antibiotics simultaneously, leading to human deaths due to a lack of effective treatments [52]. The serotype Escherichia coli 0104:H4 carrying the \(\beta\)-lactamase gene caused over 4000 infections of bloody diarrhea in Germany, leading to at least 850 cases of hemolytic uremic syndrome and 50 deaths [53]. [PERSON] revealed the widespread distribution of antibiotic resistance genes (ARGs) in the environment and their co-occurrence with degrading strains through a metagenomic analysis, indicating that degrading strains may serve as potential vectors for the spread of ARGs [54]. Therefore, future research should further optimize microbial degradation strategies or utilize microbial community regulation techniques to enhance the degradation efficiency, while also assessing their ecological safety.