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首页> 外文学位 >Biodegradation of methanol and alpha-pinene using thermophilic bacteria and its application in thermophilic biofiltration systems.
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Biodegradation of methanol and alpha-pinene using thermophilic bacteria and its application in thermophilic biofiltration systems.

机译：使用嗜热细菌对甲醇和α-pine烯进行生物降解及其在嗜热生物过滤系统中的应用。

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摘要

The overall goal of this study was to recover and characterize thermophilic bacteria that can degrade the VOCs methanol and α-pinene and to develop a bench-scale thermophilic biofiltration system for the removal of these VOCs.; Thermophilic bacterial mixtures that degrade both methanol and α-pinene were obtained via enrichment techniques. Two tested bench-scale thermophilic biofiltration systems utilizing these bacteria were designed to treat VOCs under conditions, particularly temperatures between 50 and 60°C, commonly found in the waste stream of forest product industries such as oriented strand board mills. The first system had removal efficiencies of >98% for methanol but only 23% for α-pinene. α-Pinene removal was poor, likely because of mass transfer limitation (i.e., α-pinene is essentially immiscible). The second system, having the same parameters as the first system except being larger in size, was designed and operated to evaluate residence time and the effects of surfactants on VOC removal. A nonionic surfactant mixture (having concentrations of 0.05% w/v for Triton X-100, 0.1% w/v for Brij 35 and 0.05% for Brij 58) when added to system resulted in increased α-pinene removal, indicating that the surfactants may increase mass transfer and bioavailability of α-pinene.; An additional study was conducted to further investigate the effects of nonionic surfactants on α-pinene solubility and on the thermophilic biodegradation of methanol and α-pinene in liquid systems. A test of solubility enhancement of α-pinene by surfactants utilized the same surfactants mixture as was used in the second bïofiltration system, as well as each surfactant in the mixture individually and at various concentrations. All three nonionic surfactants were able to linearly increase α-pinene concentrations in water, although each did so to a different extent. When testing thermophilic biodegradation, over 99.9% of the α-pinene was degraded within 8 h (k of 0.27/h) with surfactants. In contrast, only 4% of the α-pinene was degraded without surfactants (k of 0.08/h). Maximum degradation rates of α-pinene with and without surfactants were 50.6 mg/l/h and 0.15 mg/l/h, respectively. The surfactants did not affect growth rates on methanol nor methanol degradation. Tests also showed that the surfactants neither served as nutrient sources nor were toxic to the bacteria. Therefore the results indicate that nonionic surfactants may be successfully employed to enhance α-pinene degradation under thermophilic conditions by increasing its solubility, mass transfer, and bioavailability, while not adversely affecting methanol degradation.; The final phase of this thesis focused on the characterization of the thermophilic methanol-utilizing facultative methylotrophs by using both phenotypic and molecular techniques. The major recoverable isolates of both methanol and α-pinene bacterial mixtures appeared similar. The bacteria were able to utilize both methanol and multicarbon compounds, thus the recovered bacteria were considered to consist of facultative methylotrophs. Phenotypic and molecular (i.e., 16S rRNA gene sequences) characteristics revealed that none of isolates matched closely to any published thermophilic or methylotrophic species. At least two new thermophilic methanol-utilizing methylotrophs have been found. One isolate should belong to the Deinococus-Thermus phylum, the other two isolates should belong to Gammaproteobacterium class and in the Proteobacterium phylum.
机译：这项研究的总体目标是回收和鉴定可降解VOC的甲醇和α-pine烯的嗜热细菌，并开发一种台式规模的嗜热生物过滤系统以去除这些VOC。通过富集技术获得了降解甲醇和α-pine烯的嗜热细菌混合物。设计了两个利用这些细菌的经过测试的台式嗜热生物过滤系统，用于在一定条件下（特别是在50至60°C的温度下）处理VOC，这些条件通常出现在林业产品行业（例如定向刨花板工厂）的废物流中。第一个系统对甲醇的去除效率> 98％，但对α-pine烯的去除效率仅为23％。 α-P烯的去除很差，可能是由于传质限制（即α-pine烯基本上不混溶）。设计和运行第二个系统，该系统具有与第一个系统相同的参数，只是尺寸更大，用于评估停留时间以及表面活性剂对VOC去除的影响。当添加到系统中时，非离子表面活性剂混合物（Triton X-100的浓度为0.05％w / v，Brij 35的浓度为0.1％w / v，Brij 58的浓度为0.05％）导致α-pine烯的去除率增加，表明表面活性剂可能会增加α-pine烯的传质和生物利用度。进行了另一项研究，以进一步研究非离子表面活性剂对液体体系中α-pine烯的溶解度以及甲醇和α-pine烯的嗜热生物降解的影响。用表面活性剂提高α-pine烯的溶解度的测试使用了与第二次过滤系统中使用的相同的表面活性剂混合物，以及混合物中的每种表面活性剂分别以不同的浓度使用。所有三种非离子表面活性剂均能够线性增加水中的α-pine烯浓度，尽管每种方法的程度不同。当测试嗜热生物降解时，表面活性剂在8小时内降解了超过99.9％的α-pine烯（k为0.27 / h）。相反，在没有表面活性剂的情况下，只有4％的α-pine烯被降解（k为0.08 / h）。有和没有表面活性剂的α-pine烯的最大降解率分别为50.6 mg / l / h和0.15 mg / l / h。表面活性剂不影响甲醇的生长速率或甲醇降解。测试还表明，表面活性剂既不作为营养来源也不对细菌有毒。因此，结果表明非离子表面活性剂可通过增加其溶解度，传质和生物利用度而在嗜热条件下成功地用于增强α-pine烯的降解，而不会不利地影响甲醇的降解。本文的最后阶段着重于通过表型和分子技术对嗜热甲醇利用的兼性甲基营养型进行表征。甲醇和α-pine烯细菌混合物的主要可回收分离物似乎相似。细菌能够利用甲醇和多碳化合物，因此回收的细菌被认为是兼性甲基营养型。表型和分子（即16S rRNA基因序列）特征表明没有分离株与任何已发表的嗜热或甲基营养物种紧密匹配。已经发现至少两个新的利用甲醇的嗜热甲醇营养菌。一种分离株应属于 Deinococus-Thermus 门，另外两种分离株应属于γproteobacterium类和 Proteobacterium phylum。

著录项

  • 作者

    Dhamwichukorn, Srisuda.;

  • 作者单位

    Michigan Technological University.;

  • 授予单位 Michigan Technological University.;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 p.2592
  • 总页数 183
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 微生物学;
  • 关键词

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