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首页> 外文学位 >Biochemical and genetic characterisation of cerein 7 and cerein 8, two novel bacteriocins produced by Bacillus cereus Bc7, isolated from a soil sample.
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Biochemical and genetic characterisation of cerein 7 and cerein 8, two novel bacteriocins produced by Bacillus cereus Bc7, isolated from a soil sample.

机译：蜡状芽孢杆菌Bc7产生的两种新的细菌素cerein 7和cerein 8的生化和遗传特性，从土壤样品中分离出来。

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摘要

Many bacteria produce different antibiotic compounds that provide them with adaptative advantage against competitors in natural environments. Some of these compounds can be used in controlling natural populations by acting on targets different than those blocked by most of the currently used antibiotics.;On the other hand, the use of these compounds as food preservatives increases their economic interest. On this context, several soil isolates belonging to the genus Bacillus were screened for bactericidal activity and two of them were found to produce antimicrobial substances: Bacillus megaterium Bm38 and Bacillus cereus Bc7; Bc7 showed the strongest inhibitory activity. The aim of the present work is to understand the biochemical and genetic determinants involved in the production of Bc7 antimicrobial activity. The results of this study will increase the tools for the fight against infectious diseases.;Bacillus cereus Bc7 produces heat stable antibiotic peptides (bacteriocins), active against a large number of Gram-positive bacteria (including Listeria species) but inactive against Gram-negatives. Purification to homogeneity by hydrophobic-interaction, cation-exchange, and reverse-phase liquid chromatography (FPLC) revealed that Bacillus cereus Bc7 produces two bacteriocins, cerein-7 and cerein-8 that can be distinguished by their N-terminal amino acid sequences (N-Gly-Trp-Gly-Asp-Val-Leu for cerein-7 and N-Gly-Trp-Trp-Asn-Ser-Trp-Gly-Lys for cerein-8). Their mode of action is bactericidal and, in some cases, bacteriolytic, suggesting a "two steps" mechanism in which a primary effect disrupts membrane integrity causing cell death in many bacilli whereas, in some cocci, a secondary effect triggers autolytic processes in susceptible bacteria.;The gene encoding cerein-8 was sequenced, its primary translation product was a 74 amino-acids peptide containing a leader sequence of the double-glycine type. This leader peptide is proteolytically processed to produce the mature cerein-8 of 56 amino-acids, with a theoretical molecular weight of 4.893. The deduced sequence of the leader peptide of 18 amino-acids indicates that it is related to sec-independent N-terminal extensions.
机译：许多细菌会产生不同的抗生素化合物，从而使其具有对抗自然环境中竞争者的适应性优势。这些化合物中的某些可以通过作用于不同于大多数当前使用的抗生素所阻止的目标而用于控制自然种群。另一方面，将这些化合物用作食品防腐剂增加了其经济利益。在此背景下，筛选了属于芽孢杆菌属的几种土壤分离物的杀菌活性，发现其中两个产生了抗菌物质：巨大芽孢杆菌Bm38和蜡状芽孢杆菌Bc7。 Bc7表现出最强的抑制活性。本工作的目的是了解参与Bc7抗菌活性生产的生化和遗传决定因素。这项研究的结果将为抗击传染病提供更多工具。蜡状芽孢杆菌Bc7产生热稳定的抗生素肽（细菌素），对许多革兰氏阳性细菌（包括利斯特氏菌属）有活性，但对革兰氏阴性菌无活性。通过疏水相互作用，阳离子交换和反相液相色谱（FPLC）纯化至均质性显示蜡状芽孢杆菌Bc7产生两种细菌素，cerein-7和cerein-8可通过其N端氨基酸序列区分（对于Cerinin-7为N-Gly-Trp-Gly-Asp-Val-Leu，对于Cerein-8为N-Gly-Trp-Trp-Asn-Ser-Trp-Gly-Lys。它们的作用方式具有杀菌作用，在某些情况下具有溶菌作用，这表明了“两步”机制，其中主要作用破坏了膜的完整性，导致许多杆菌死亡，而在某些球菌中，次要作用触发了易感细菌的自溶过程。 ；对编码cerein-8的基因进行测序，其主要翻译产物是含有双甘氨酸型前导序列的74个氨基酸的肽。该前导肽经蛋白水解处理以产生具有56个氨基酸的成熟cerein-8，理论分子量为4.893。推导的18个氨基酸的前导肽序列表明，它与sec独立的N端延伸有关。

著录项

  • 作者

    Oscariz Rada, Juan Carlos.;

  • 作者单位

    Universidad Publica de Navarra (Spain).;

  • 授予单位 Universidad Publica de Navarra (Spain).;
  • 学科 Microbiology.;Molecular biology.;Biochemistry.;Pharmacy sciences.
  • 学位 Dr.
  • 年度 2000
  • 页码 76 p.
  • 总页数 76
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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