Meng Qingxin, Huang Rong, Xun Lijie, Wu Xiaoman, Deng Shangkao, Yue Dan, Zhao Wenzheng, Dong Xia, Gong Xueyang, Dong Kun
Yunnan Provincial Engineering and Research Center for Sustainable Utilization of Honey Bee Resources, Eastern Bee Research Institute, College of Animal Science and Technology, Yunnan Agricultural University, Kunming, China.
Institute of Sericulture and Apiculture, Yunnan Academy of Agricultural Sciences, Mengzi, China.
Front Microbiol. 2024 Oct 21;15:1459354. doi: 10.3389/fmicb.2024.1459354. eCollection 2024.
, an ancient plant species endemic to Yunnan Province, China, remains underexplored in terms of its endophytic bacterial communities. The plant tissue pedicel serves as the connection between the flower and the stem, not only delivers nutrients but also transmits metabolic substances from endophytic bacteria to the nectar during long-term microbial colonization and probably improves the antagonistic activity of nectar against yeast. Hence, 138 isolates of endophytic bacteria have been isolated in this study from the pedicels of 12- and 60-year-old . Comparative analysis revealed significantly higher density of endophytic bacteria in older trees. Among these isolates, 29 exhibited inhibitory effects against nectar yeasts. Most of the isolates displayed positive results for Gram staining, catalase reaction, gelatin liquefaction, and motility. Additionally, the isolates demonstrated the ability to utilize diverse substrates, such as glucose, nitrate, and starch. Based on 16S rRNA molecular biology analysis, these isolates were identified to be 11 different species of 6 genera, with the majority belonging to genus. Notably, C1 isolate, identified as , exhibited strongest antagonistic effect against three yeasts, i.e., , and , with minimum inhibitory concentration values below 250 μg/mL. Major metabolites of were aminoglycosides, beta-lactams, and quinolones, which possess antimicrobial activities. Furthermore, KEGG enrichment pathways primarily included the synthesis of plant secondary metabolites, phenylpropanoids, amino acids, alkaloids, flavonoids, neomycin, kanamycin, and gentamicin. Therefore, antagonistic activity of against yeasts could be attributed to these antibiotics. The findings highlight the diverse endophytic bacteria associated with , indicating their potential as a valuable resource of bioactive metabolites. Additionally, this study provides new insights into the role of endophytic bacteria of pedicels in enhancing nectar resistance against yeasts.
[植物名称]是中国云南省特有的一种古老植物物种，其内生细菌群落仍未得到充分研究。植物组织花梗作为花与茎之间的连接部分，不仅输送养分，还在长期微生物定殖过程中将内生细菌的代谢物质传递到花蜜中，可能提高花蜜对酵母的拮抗活性。因此，本研究从12年和60年树龄的[植物名称]花梗中分离出138株内生细菌。比较分析显示，老龄树中内生细菌的密度显著更高。在这些分离株中，29株对花蜜酵母表现出抑制作用。大多数分离株革兰氏染色、过氧化氢酶反应、明胶液化和运动性检测呈阳性。此外，这些分离株表现出利用多种底物的能力，如葡萄糖、硝酸盐和淀粉。基于16S rRNA分子生物学分析，这些分离株被鉴定为6个属的11个不同物种，其中大多数属于[属名]属。值得注意的是，被鉴定为[菌株名称]的C1分离株对三种酵母，即[酵母名称1]、[酵母名称2]和[酵母名称3]表现出最强的拮抗作用，最低抑菌浓度值低于250μg/mL。[菌株名称]的主要代谢产物为氨基糖苷类、β-内酰胺类和喹诺酮类，具有抗菌活性。此外，KEGG富集途径主要包括植物次生代谢产物、苯丙烷类、氨基酸、生物碱、黄酮类、新霉素、卡那霉素和庆大霉素的合成。因此，[菌株名称]对酵母的拮抗活性可能归因于这些抗生素。这些发现突出了与[植物名称]相关的多样内生细菌，表示它们作为生物活性代谢物宝贵资源的潜力。此外，本研究为花梗内生细菌在增强花蜜对酵母抗性中的作用提供了新的见解。
