Botany and Microbiology Department, Faculty of Science, Suez Canal University, Ismailia, 41522, Egypt.
Folia Microbiol (Praha). 2022 Feb;67(1):81-89. doi: 10.1007/s12223-021-00911-y. Epub 2021 Sep 16.
The endophytic actinobacteria associated with Artemisia herba-alba (synonym: Seriphidium herba-alba) are highly diverse. This study aimed to illustrate the extent of their differences from the free-living actinobacteria in the surrounding environment. A selection of eighteen actinobacteria inhabiting A. herba-alba were compared with twenty and ten actinobatceria isolates from the surrounding desert and groundwater, respectively, representing six genera. Antagonistic and enzymatic activities, plant growth-promoting traits, and the occurrence of biosynthetic genes were compared among the isolates. Data were analyzed statistically using principal component analysis (PCA) and were visualized using heat map. Endophytic strains showed higher antimicrobial activity and production of plant growth promoters compared to desert and groundwater strains. Polyketide synthase and non-ribosomal peptide synthetase gene clusters were detected at higher frequencies in the endophytic strains (8 and 11 strains, respectively) than the desert strains (1 and 2 strains, respectively). In contrast, both gene clusters were not detected in the groundwater strains. The PCA revealed unique metabolic characteristics of the endophytes. The heatmap clustered the endophytic strains apart from the free-living strains, indicating distinctive qualitative and quantitative bioactivities. Analysis of 16S rRNA genes confirmed the chemotaxonomic identity of all but two strains, with > 94.5% similarity. Six endophytes displayed < 99.5% similarity with their closest type strains, which might indicate species novelty. This study provides an evidence of functional differences and possible species novelty of the endophytic actinobacteria inhabiting A. herba-alba, compared with the free-living species.
与黄花蒿（同义词：苦蒿）相关的内生放线菌具有高度多样性。本研究旨在阐明其与周围环境中自由生活放线菌的差异程度。选择了 18 株内生放线菌与分别来自周围沙漠和地下水的 20 株和 10 株放线菌进行比较，代表 6 个属。比较了分离株之间的拮抗和酶活性、植物促生长特性和生物合成基因的发生情况。使用主成分分析（PCA）对数据进行统计分析，并使用热图进行可视化。与沙漠和地下水菌株相比，内生菌株显示出更高的抗菌活性和植物生长促进剂的产生。聚酮合酶和非核糖体肽合成酶基因簇在内生菌株（分别为 8 株和 11 株）中的检出频率高于沙漠菌株（分别为 1 株和 2 株）。相比之下，这两个基因簇都没有在地下水菌株中检测到。PCA 揭示了内生菌独特的代谢特征。热图将内生菌株与自由生活菌株聚类分开，表明其具有独特的定性和定量生物活性。16S rRNA 基因分析证实了除两株外所有菌株的化学分类学同一性，相似度>94.5%。有 6 株内生菌与最接近的模式菌株的相似度<99.5%，这可能表明它们具有物种新颖性。本研究提供了证据表明，与自由生活的物种相比，栖息在黄花蒿中的内生放线菌具有功能上的差异和可能的物种新颖性。
