Over the last century, polycyclic aromatic hydrocarbons (PAHs) have been discharged into the ecosystems through natural and human activities owing to increased population growth and industrial activities, such as fossil fuels [1]. Anthracene is a typical contaminant of PAHs and is often used in the preparation of scintillators, wood preservatives, paints, and plastics [2], causing severe harm to the ecological environment, such as soil and groundwater. It affects the survival of plants, animals, and microorganisms because it easily binds to organisms and damages their DNA and RNA [3]. In addition, its accumulation due to food chain enrichment poses a serious risk to human health [4]. Therefore, it is crucial to explore anthracene remediation techniques [5]. Microbial remediation is widely used because of less secondary contamination, lower cost, and higher efficiency [6].

In recent years, scholars have conducted a preliminary exploration of the biodegradation process of anthracene. Dioxygenase is the key rate-limiting enzymes for the degradation of PAHs. Firstly, it oxidizes to generate anthraquinone and the benzene ring cleavage to form phthalic acid, which is converted to benzoic acid. Finally, the degradation process is completed by the biosynthesis and utilization of fatty acid and tricarboxylic acid cycle (TCA) [7,8].

Erythromycin was one of the highest antibiotics detected in the Pearl River Delta region in China, and its residual amount in the environment is large and antibacterial [9]. The erythromycin cannot be completely absorbed by humans and animals, and most of them are excreted into the environment by feces and urine as secondary contaminants, causing serious contamination of soil and water resources [10]. The residues of erythromycin in the environment are only in trace amounts, but still have strong antibacterial effects that exceed the tolerance range of microorganisms, making it difficult to survive in the soil or water, and the biodegradation effect is significantly reduced [11]. Therefore, erythromycin was selected for follow-up studies. However, in previous reports [12], the coercive effect of erythromycin on microorganisms in the environment was often not taken into account in the degradation of anthracene, and this topic has to be addressed in practical applications.

Herein, we selected four natural macrocyclic degrading bacteria, from which we screened the best strain for anthracene degradation, and the critical gene responsible for anthracene biodegradation was identified by transcriptome analysis. Furthermore, the function of this crucial gene in the anthracene biodegradation was further determined by genetic manipulation.