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首页> 外文学位 >Bacterial diversity of the octocoral Pseudopterogorgia elisabethae via culture-dependent and culture-independent methods and screening of selected bacteria for antimicrobial activity.
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Bacterial diversity of the octocoral Pseudopterogorgia elisabethae via culture-dependent and culture-independent methods and screening of selected bacteria for antimicrobial activity.

机译：通过依赖于培养物和不依赖于培养物的方法以及筛选所选细菌的抗菌活性来确定八叶拟南芥的细菌多样性。

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摘要

Alcyonacean octocorals (Order Alcyonacea, amended from Order, Gorgoniidae) are both dominant on Caribbean reefs and prolific sources of bioactive natural products. Although extensive literature has been published with respect to stony coral-associated bacteria, very little is known regarding bacterial populations in healthy octocorals. In this thesis, the octocoral Pseudopterogorgia elisabethae was selected as a model organism to investigate owing to its commercial significance and its understudied bacterial community. The overall hypothesis of this thesis is that the bacterial community of P. elisabethae is diverse and can be cultured to produce a valuable and sustainable source of novel natural products. To test this hypothesis, three studies were performed. In the first investigation, pyrosequencing was used to examine the culture independent bacterial community in P. elisabethae. In the second study, bacteria were isolated from P. elisabethae using nine diverse isolation media to maximize the number of isolates. The final approach involved assessing the ability of bacterial isolates to produce antimicrobial compounds via screening fermentation extracts against five clinically relevant pathogens.;Pyrosequencing results from 14 coral-associated bacterial sequence libraries suggested P. elisabethae individuals are a rich source of diverse and novel bacteria. Bacterial communities were analyzed at the class and the species level, where a lack of conservation between conspecifics within and between reefs in the Bahamas was observed. From the culturing approach, 852 bacteria were isolated and were de-replicated by MALDI-TOF MS to approximately 78 unique isolates. In addition, sequences generated from de-replicated isolates were compared to the pyrosequencing community at 97% sequence similarity, yet very little overlap (0.44%) was observed. Regardless, de-replicated isolates were screened for antimicrobial activity, where a Streptomyces sp. RKBH-B54 and genetically-related Pseudoalteromonasspp. were reproducibly bioactive against yeast and Gram-positive bacteria respectively. Due to the potent bioactivity of RKBH-B54, a bioassay guided fractionation was performed in an attempt to isolate the antifungal compound produced. Dihydromaltophilin and maltophilin were proposed as the most likely compounds responsible for the observed antifungal activity from RKBH-B54 based on comparison of UPLC/HRMS data to analytical databases; unfortunately, the instability of these compounds prevented complete purification and structural elucidation. In conclusion, this thesis has demonstrated that P. elisabethae is a rich source of diverse bacteria, yet collecting multiple individuals throughout the Bahamas is required to truly evaluate the microbial biodiversity in this octocoral. It is also concluded that the potent and reproducible bioactivity of selected bacterial extracts from P. elisabethae can be used as a resource for developing potentially new therapeutic agents.
机译：Alcyonacean octocorals（订单Alcyonacea，从Order，Gorgoniidae修改）在加勒比礁和生物活性天然产物的多产方面均占主导地位。尽管有关石质珊瑚相关细菌的文献已经广泛发表，但关于健康八爪鱼中细菌的数量知之甚少。鉴于其商业意义和对细菌群落的深入研究，本文选择八叶拟南芥假单胞菌为研究对象。本论文的总体假设是，伊丽莎白球菌的细菌群落是多种多样的，可以进行培养以产生有价值的和可持续的新型天然产物。为了检验该假设，进行了三项研究。在第一个研究中，焦磷酸测序用于检查伊利沙伯体育中不依赖培养物的细菌群落。在第二项研究中，使用九种不同的分离培养基从大肠杆菌中分离出细菌，以使分离物的数量最大化。最终方法涉及通过筛选针对5种临床相关病原体的发酵提取物来评估细菌分离物产生抗微生物化合物的能力。;来自14个与珊瑚相关的细菌序列库的焦磷酸测序结果表明，伊丽莎白假单胞菌个体是多种新颖细菌的丰富来源。在类别和物种级别对细菌群落进行了分析，在巴哈马群岛的珊瑚礁之间和珊瑚礁之间的同种异体之间缺乏保护。从培养方法中，分离出852个细菌，并通过MALDI-TOF MS将其复制到大约78个独特的分离株中。此外，将从重复复制的分离株产生的序列与焦磷酸测序社区进行了97％的序列相似性比较，但观察到的重叠很少（0.44％）。无论如何，筛选去复制的分离物的抗微生物活性，其中链霉菌属。 RKBH-B54和与遗传相关的假单孢菌monasspp。对酵母和革兰氏阳性细菌分别具有可复制的生物活性。由于RKBH-B54具有强大的生物活性，因此进行了生物测定指导的分馏，以尝试分离产生的抗真菌化合物。根据UPLC / HRMS数据与分析数据库的比较，提出了二氢麦芽糖蛋白和麦芽糖蛋白是最有可能导致RKBH-B54产生抗真菌活性的化合物。不幸的是，这些化合物的不稳定性阻止了其完全纯化和结构阐明。总之，本论文证明了伊利沙伯体育是多种细菌的丰富来源，但是需要在巴哈马各地收集多个个体才能真正评估该八叶菌的微生物多样性。还得出结论，从伊丽莎白酵母中选择的细菌提取物的有效和可再现的生物活性可以用作开发潜在的新治疗剂的资源。

著录项

  • 作者

    Robertson, Veronica.;

  • 作者单位

    University of Prince Edward Island (Canada).;

  • 授予单位 University of Prince Edward Island (Canada).;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 352 p.
  • 总页数 352
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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