喀麦隆土壤柴油降解酵母的分离与鉴定以及其降解特性的研究

发布时间：2024-12-11 00:12

　　从喀麦隆先前没有被石油烃污染的土壤样品中分离获得一株柴油降解酵母KML。根据其形态特征,生理生化特性和5.8S rDNA-ITS基因序列分析,这株酵母菌被认定为解脂耶罗维亚酵母菌(Yarrowia lipolytica)。通过单因素变量法研究各种因素对这株菌降解能力的影响。结果显示：在20、30、37℃三种不同温度下测试其降解率,30℃为最适温度,约有59.0%的柴油被降解。通过不同的最初pH测试(分别为6、7、8、9和10),最适最初pH值为9,约75.1%的柴油被降解。培养基中不同的氮源对KML柴油降解率影响试验影响结果显示：浓度为1mg/ml的酵母提取物为最好的氮源,降解的柴油为76.8%；培养基中添加浓度为10mg/ml的鼠李糖作为生物表面活性剂的情况下KML柴油降解率最高可达到78.0%。 不同的生物接种量也影响到KML降解率。接种量分别为7×106、3.8×107、4.7×108和2.8×109cells/ml情况下,其对应的柴油降解率分别为66.1,61.2,55.1和54.0%。分离菌株在含浓度为10%-5%柴油的培养基中均能降解柴油。 气相色谱-质谱法(GC-M...

【文章页数】：88 页

【学位级别】：硕士

【文章目录】：
摘要
ABSTRACT
Chapter 1 Literature review
    1.1 Use of petroleum and its products
    1.2 Components in crude oil or petroleum
    1.3 Environmental issues of petroleum
    1.4 Methods to clean up petroleum
        1.4.1 Mechanical method
        1.4.2 Chemical method
        1.4.3 Physical method
        1.4.4 Biological method
    1.5 Microorganims degrading petroleum hydrocarbons
    1.6 Mechanisms of hydrocarbons biodegradation
    1.7 Factors affecting the biodegradation
        1.7.1 Physical state of oil
        1.7.2 Temperature
        1.7.3 Nutrients
        1.7.4 Others factors
    1.8 Presentation of Cameroon and objectives of this work
        1.8.1 Cameroon
        1.8.2 Objectives and scope of this study
        1.8.3 Plan of the thesis
    References
Chapter 2 Isolation and identification of diesel degrading microorganisms
    2.1 Introduction
    2.2 Materials
        2.2.1 Microorganisms source
        2.2.2 Medium and reagents
            2.2.2.1 Media
            2.2.2.2 Reagents
        2.2.3 Main reagents
        2.2.4 Equipments
    2.3 Methods
        2.3.1 Isolation of microorganisms
        2.3.2 Screening of diesel oil degrading microorganisms
        2.3.3 Identification of the isolate
            2.3.3.1 Morphological characteristics of colonies on the plate
            2.3.3.2 Microscopic appearance of cells
            2.3.3.3 Physiological and biochemical tests
            2.3.3.4 Molccular identification
    2.4 Results and discussion
        2.4.1 Results
            2.4.1.1 Morphogical characteristics of isolate KML
            2.4.1.2 Physiological and biochemical characteristics
            2.4.1.3 Molecular identification
        2.4.2 Discussion
    2.5 Conclusions
    References
Chapter3 Biodegradation of diesel oil by isolate KML
    3.1 Introduction
    3.2 Materials
        3.2.1 Microorganisms source
        3.2.2 Media and reagents
            3.2.2.1 Media
            3.2.2.2 Reagents
        3.2.3 Chemicals
        3.2.4 Equipments
    3.3 Methods
        3.3.1 Enrichment method
        3.3.2 Biodegradation studies
            3.3.2.1 Inoculum preparation
            3.3.2.2 Standard curve of diesel
            3.3.2.3 Time course of diesel oil degradation by isolate KML
        3.3.3 Effects of various factors on the biodegradation
            3.3.3.1 Effect of temperature
            3.3.3.2 Effect of pH on diesel oil degradation
            3.3.3.3 Effect of different nitrogen sources on diesel degradation
            3.3.3.4 Effect of different yeast concentration
            3.3.3.5 Effect of different rhamnolipid concentration
            3.3.3.6 Effect of different inoculum concentration
            3.3.3.7 Effect of different diesel oil concentration
    3.4 Results and discussion
        3.4.1 Results
            3.4.1.1 Standard curve of diesel oil concentration
            3.4.1.2 Biodegradation essay of isolate KML
            3.4.1.3 Effect of pH
            3.4.1.4 Effect of temperature on diesel degradaiton by isolate KML
            3.4.1.5. Effect of different nitrogen sources
            3.4.1.6 Effect of yeast extract concentration
            3.4.1.7 Effect of rhamnolipid concentration
            3.4.1.8. Effect of inoculum concentration
            3.4.1.9 Effect of diesel oil concentration on diesel degradation by isolate KML
        3.4.2 Discussion
    3.5 Conclusions
    References
Chapter 4 GC-MS analysis of diesel oil components
    4.1 Introduction
    4.2 Materials
        4.2.1 Medium and chemicals
        4.2.2 Equipments
    4.3 Methods
    4.4. Results and discussion
    4.5 Conclusions
    References
Chapter 5 Conclusion and future work
    5.1 Conclusions
    5.2 Future work
Acknowledgements
Publications



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