• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Recombinant protein production in Bacillus species, isolation and methionine production in methionine-producing microorganisms.
【24h】

Recombinant protein production in Bacillus species, isolation and methionine production in methionine-producing microorganisms.

机译：芽孢杆菌属物种的重组蛋白生产，蛋氨酸生产微生物中的分离和蛋氨酸生产。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Linoleic acid isomerase (LAI) is the enzyme that converts linoleic acid to conjugated linoleic acids (CLAs) which appear to be capable of lowering cancer risk and enhancing immunity. There is an interest in developing commercial processes for the production of single isomers of CLA by biotransformation of LA using microbial cells and enzymes. However, the evaluation of these strains suggest that growth and LA isomerase production levels by these anaerobes are insufficient to support economic commercial production of single CLA isomers. A better alternative is to clone the isomerase gene and to generate new production strains using recombinant technology. Bifidobacterium LAI genes were cloned into pET24a(+) as an expression vector and transferred into E. coli BL21 (DE3) as the expression host while Propionibacterium acnes LAI were cloned into Bacillus species as the expression hosts. Unfortunately, the expressed Bifodobacterium LAI formed inclusion bodies and did not exhibit detectable enzymatic activities. Propeptide Staphylococcus hyicus lipase fused with P. acnes LAI expressed in B. megaterium YYBm1 was secreted into the surrounding medium. Based on MALDI-TOF MS results showed that this propeptide S. hyicus lipase still attached with the secreted LAI and might inhibit activity. However, other propeptides ( B. subtilis nprE, B. subtilis amyE, B. megaterium nprM) did not protect LAI from proteolytic degradation.;Methionine is the first limiting amino acid in poultry feed and must be supplemented to the poultry feed mixture. Many studies attempted to isolate methionine producing microoragnisms from environments and genetically modified by using chemical mutagens. However, genetically-modified organisms are considered unacceptable for use in organic food production. Therefore, wild type strains with methionine-producing ability are necessary for the organic poultry industry. In this study, numerous bacteria were isolated from natural environments that appeared to produce high methionine; however, all of them were identified as pathogens. In addition, bacteria excreted methionine into the surrounding medium and it was concluded that this could be impractical for large scale recovery of methionine. Conversely, isolated yeast strain K1 yielded high methionine content, compared to other yeasts. Based on large subunit rRNA sequences, these isolated strains were identified as Pichia kudriavzevii/Issatchenkia orientalis. P. kudriavzevii/I. orentalis is recognized as a "generally recognized as safe" (GRAS) organism. Yeast strain K1 may be suitable as a source of methionine for dietary supplements in organic poultry feed.
机译：亚油酸异构酶（LAI）是将亚油酸转化为共轭亚油酸（CLA）的酶，似乎可以降低癌症风险并增强免疫力。有兴趣开发通过使用微生物细胞和酶通过LA的生物转化来生产CLA的单一异构体的商业方法。但是，对这些菌株的评估表明，这些厌氧菌的生长和LA异构酶的生产水平不足以支持单一CLA异构体的经济商业生产。更好的替代方法是克隆异构酶基因，并使用重组技术产生新的生产菌株。将双歧杆菌的LAI基因克隆到表达载体pET24a（+）中，并转移到作为表达宿主的大肠杆菌BL21（DE3）中，而痤疮丙酸杆菌LAI则克隆到芽孢杆菌中作为表达宿主。不幸的是，表达的双歧杆菌LAI形成包涵体并且没有表现出可检测的酶活性。与巨大芽孢杆菌YYBm1中表达的痤疮丙酸杆菌LAI融合的前肽葡萄球菌脂肪酶被分泌到周围的培养基中。基于MALDI-TOF MS结果表明，该肽原葡萄球菌脂肪酶仍与分泌的LAI结合，并可能抑制其活性。然而，其他前肽（枯草芽孢杆菌nprE，枯草芽孢杆菌amyE，巨大芽孢杆菌nprM）不能保护LAI免受蛋白水解降解。蛋氨酸是家禽饲料中的第一个限制性氨基酸，必须添加到家禽饲料混合物中。许多研究试图从环境中分离出产生蛋氨酸的微生物，并使用化学诱变剂对其进行了基因改造。然而，转基因生物被认为不能用于有机食品生产。因此，对于有机家禽业来说，具有蛋氨酸生产能力的野生型菌株是必需的。在这项研究中，从自然环境中分离出许多细菌，这些细菌似乎会产生高蛋氨酸。但是，它们都被确定为病原体。另外，细菌将蛋氨酸排到周围的培养基中，因此得出结论，这对于大规模回收蛋氨酸可能是不切实际的。相反，与其他酵母相比，分离的酵母菌株K1产生的蛋氨酸含量较高。基于大的亚基rRNA序列，这些分离出的菌株被鉴定为库氏毕赤酵母/东方伊萨氏菌。 P. kudriavzevii / I。齿肠被认为是“一般公认的安全”（GRAS）生物。酵母菌株K1可能适合作为有机家禽饲料中膳食补充剂蛋氨酸的来源。

著录项

  • 作者

    Saengkerdsub, Suwat.;

  • 作者单位

    University of Arkansas.;

  • 授予单位 University of Arkansas.;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 177 p.
  • 总页数 177
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号