深海覆盖了地球表面超过70%的面积，其中绝大部分都是未知的细菌群落。放线菌是生物活性天然产物的主要原源，这些产物被用于药物发现项目中，并且深海是寻找与生物技术相关的放线菌的有前途来源。以前对深海沉积物中的放线菌研究范围局限于特定区域，或者没有将社区特征与生物活性潜力分析结合起来。本研究使用16S rRNA metabarcoding表征了来自北极和大西洋（亚速尔群岛和马德拉）海盆上层深海沉积物的放线菌群落，并研究了从这些样品中提取的可培养放线菌的生物合成潜力。Metabarcoding分析显示，放线菌的组成在样本区域之间有所不同，北极样本的丰度更高，而大西洋样本的多样性更高。利用无培养方法检测到了20个放线菌属，而依赖培养的方法只发现了9个属。放线菌的分离得到了44个菌株，主要属于短杆菌属、微球菌属和短细菌属。其中部分分离物仅在特定的采样区域中被鉴定。随后对放线菌的化学提取物进行了抗微生物、抗癌和抗炎症活性筛选。两个链霉菌菌株的提取物对念珠菌表现出了活性。此外，八个提取物 (来自短杆菌属、短细菌属、微球菌和链霉菌菌株)对至少一个测试的癌细胞系 (HepG2和T-47D)显示出显著活性。此外，15个放线菌提取物在RAW 264.4细胞模型测定中表现出抗炎作用，并没有伴随细胞毒性反应。生物活性放线菌提取物的去重和分子网络分析显示存在一些与已知天然产物相关的代谢物，但分析的某一群集没有与作为这些生物活性原因的自然产物相匹配。总体而言，我们能够从所研究的深海样本中恢复出不同生物活性的分类学多样性放线菌。培养依赖和非依赖方法的结合有助于更好地理解深海环境中的放线菌多样性，这对于获得新的化学丰富菌株的优化方法很重要。版权所有©2023 Ribeiro、Antunes、Alexandrino、Tomasino、Almeida、Hilário、Urbatzka、Leão、 Mucha和Carvalho。

The deep-sea covers over 70% of the Earth's surface and harbors predominantly uncharacterized bacterial communities. Actinobacteria are the major prokaryotic source of bioactive natural products that find their way into drug discovery programs, and the deep-sea is a promising source of biotechnologically relevant actinobacteria. Previous studies on actinobacteria in deep-sea sediments were either regionally restricted or did not combine a community characterization with the analysis of their bioactive potential. Here we characterized the actinobacterial communities of upper layers of deep-sea sediments from the Arctic and the Atlantic (Azores and Madeira) ocean basins, employing 16S rRNA metabarcoding, and studied the biosynthetic potential of cultivable actinobacteria retrieved from those samples. Metabarcoding analysis showed that the actinobacterial composition varied between the sampled regions, with higher abundance in the Arctic samples but higher diversity in the Atlantic ones. Twenty actinobacterial genera were detected using metabarcoding, as a culture-independent method, while culture-dependent methods only allowed the identification of nine genera. Isolation of actinobacteria resulted on the retrieval of 44 isolates, mainly associated with Brachybacterium, Microbacterium, and Brevibacterium genera. Some of these isolates were only identified on a specific sampled region. Chemical extracts of the actinobacterial isolates were subsequently screened for their antimicrobial, anticancer and anti-inflammatory activities. Extracts from two Streptomyces strains demonstrated activity against Candida albicans. Additionally, eight extracts (obtained from Brachybacterium, Brevibacterium, Microbacterium, Rhodococcus, and Streptomyces isolates) showed significant activity against at least one of the tested cancer cell lines (HepG2 and T-47D). Furthermore, 15 actinobacterial extracts showed anti-inflammatory potential in the RAW 264.4 cell model assay, with no concomitant cytotoxic response. Dereplication and molecular networking analysis of the bioactive actinobacterial extracts showed the presence of some metabolites associated with known natural products, but one of the analyzed clusters did not show any match with the natural products described as responsible for these bioactivities. Overall, we were able to recover taxonomically diverse actinobacteria with different bioactivities from the studied deep-sea samples. The conjugation of culture-dependent and -independent methods allows a better understanding of the actinobacterial diversity of deep-sea environments, which is important for the optimization of approaches to obtain novel chemically-rich isolates.Copyright © 2023 Ribeiro, Antunes, Alexandrino, Tomasino, Almeida, Hilário, Urbatzka, Leão, Mucha and Carvalho.