## 3 Results and Discussion
### Analysis of Plasmid Presence and Antibiotic Resistance Genes
#### 3.6.6 Other Gene Clusters  
BGC Region 4 Derived from _Lentzea_ sp. JNUCC 0626  
The antiSMASH analysis of BGC region 4 revealed a low similarity (-7%) to the known platencin BGC, suggesting limited direct relevance to platencin analog production. Further KnownClusterBlast analysis found that protein XJ15412 shares 51.3% amino acid sequence identity with MaoC/PaaZ C-terminal domain-containing protein (Ptn). Additionally, protein XJJ15443, located at the terminal end of region 4, demonstrated 54.31% identity to PtnO7, a member of the SDR family oxidoreductase [84]. Despite these findings, the genes in BGC region 4 showed higher similarity to those involved in steroid catabolism rather than secondary metabolite production, such as platencin, when compared to gene clusters found in _Salinispora arenicola_ and _Rhodococcus ruber_ Chol-4. Specifically, as illustrated in Supplementary Figure S23 and Table S34, most of the 34 proteins, from protein XJJ15410 to XJJ15443, are implicated in steroid degradation pathways [85; 86]. This discovery opens up several biotechnological applications. For instance, 3-ketosterol 9\(\alpha\)-hydroxylase (protein XJJ15415) plays a pivotal role in catalyzing hydroxylation at the 9\(\alpha\)-position of steroids, leading to the production of biologically active metabolites. This enzyme could be harnessed for developing customized pharmaceutical agents targeting specific steroidal compounds [87]. Moreover, the metabolic engineering of pathways involving these enzymes could enhance the production of steroids such as testosterone, further underscoring the potential for tailored steroid drug synthesis [88]. In addition to pharmaceutical applications, steroid degradation pathways may contribute to bioremediation by breaking down steroidal pollutants such as cholate in contaminated environments. Microbes capable of degrading steroid structures offer promising solutions for environmental cleanup [89]. Finally, enzymes involved in steroid metabolism hold the potential for synthetic biology applications, where they can be used to engineer novel metabolic pathways for the synthesis of non-natural steroid compounds. Modifying these metabolic routes could yield new biocatalysts suited to industrial applications, expanding the scope of biotechnological catalysts for steroid-related processes [90]. Thus, the steroid degradation genes identified in BGC region 4 hold significant promise for applications ranging from drug development and environmental remediation to industrial biocatalysis. BGC Region 14 Derived from _Lentzea_ sp. JNUCC 0626  
BGC region 14 was initially predicted to contain genes involved in the biosynthesis of aryl polyenes (APEs). APEs are bacterial secondary metabolites that serve as pigments and protect cells from oxidative stress. Structurally, APEs consist of a polyene chain conjugated to an aromatic ring (aryl group), giving them both antioxidant properties and their characteristic vibrant color. Recent studies on the APE BGC in _Escherichia coli_ CFT073, which is composed of 18 genes spanning 15.5 kb, confirmed that this cluster plays a critical role in APE biosynthesis. Heterologous expression experiments have successfully demonstrated the production of APEs from this BGC [91]. To investigate whether the BGC region 14 of _Lentzea_ sp. JNUCC 0626 contains genes related to APE biosynthesis, we performed a one-by-one BLASTP search on the genes in the region. Our analysis aimed to identify homologs of known APE biosynthetic genes, such as acyl carrier proteins (ACPs), 3-hydroxyacyl-ACP dehydatases, and 3-ketoacyl-ACP synthases, which are typically essential for the production of APEs. As a result, we found that region 14 contains a XJ16829 protein with homology to 3-oxoacyl-ACP synthase, a key enzyme in fatty acid biosynthesis. However, no other genes commonly associated with APE biosynthesis, including ACP, 3-hydroxyacyl-ACP dehydatases, or 3-ketoacyl-ACP synthases, were detected in this region (Figure S24, Table S35).