Actinomycetota, associated with macroalgae, remains one of the least explored marine niches. The secondary metabolism of Actinomycetota, the primary microbial source of compounds relevant to biotechnology, continues to drive research into the distribution, dynamics, and metabolome of these microorganisms. In this study, we employed a combination of traditional cultivation and metagenomic analysis to investigate the diversity of Actinomycetota in two native macroalgae species from the Portuguese coast. We obtained and taxonomically identified a collection of 380 strains, which were distributed across 12 orders, 15 families, and 25 genera affiliated with the Actinomycetia class, with Streptomyces making up approximately 60% of the composition. Metagenomic results revealed the presence of Actinomycetota in both Chondrus crispus and Codium tomentosum datasets, with relative abundances of 11% and 2%, respectively. This approach identified 12 orders, 16 families, and 17 genera affiliated with Actinomycetota, with minimal overlap with the cultivation results. Acidimicrobiales emerged as the dominant actinobacterial order in both macroalgae, although no strain affiliated with this taxonomic group was successfully isolated. Our findings suggest that macroalgae represent a hotspot for Actinomycetota. The synergistic use of both culture-dependent and independent approaches proved beneficial, enabling the identification and recovery of not only abundant but also rare taxonomic members.

中文翻译：

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揭示葡萄牙北部海岸两种大型藻类的可培养和不可培养放线菌多样性

与大型藻类相关的放线菌仍然是人们探索最少的海洋生态位之一。放线菌的次生代谢是与生物技术相关的化合物的主要微生物来源，继续推动对这些微生物的分布、动力学和代谢组的研究。在这项研究中，我们采用传统栽培和宏基因组分析相结合的方式来研究葡萄牙海岸两种本地大型藻类物种中放线菌的多样性。我们获得并分类鉴定了 380 个菌株，分布在放线菌纲的 12 个目、15 个科和 25 个属，其中链霉菌约占其组成的 60%。宏基因组结果显示，卷曲角叉菜和绒毛藻数据集中都存在放线菌，相对丰度分别为 11% 和 2%。该方法鉴定了属于放线菌门的 12 个目、16 个科和 17 个属，与培养结果的重叠最小。尽管没有成功分离出属于该分类群的菌株，但酸性微生物目已成为两种大型藻类中的主要放线菌目。我们的研究结果表明，大型藻类是放线菌的热点。事实证明，文化依赖性和独立方法的协同使用是有益的，不仅能够识别和恢复丰富的而且还能够识别和恢复稀有的分类成员。