乳酸菌分离株的特性和鉴定及其对象草和甜高粱青贮发酵品质的影响

发布时间：2022-02-13 14:56

　　象草（Pennistum Purpurem Sch.）和甜高粱（sorghum bicolor）是重要的禾本科植物,广泛种植于热带和亚热带地区,常用于调制青贮饲料。添加乳酸菌促进乳酸发酵,抑制丁酸发酵,提高了青贮饲料的发酵品质。乳酸菌的生长和活性受发酵天数,乳酸菌的初始种群,水溶性碳水化合物和干物质含量的影响[1]。本研究的目的是分离乳酸菌,通过16S r DNA序列鉴定并确定其对象草和甜高粱青贮饲料发酵品质的影响。本研究将为开发乳酸菌资源的合理利用提供理论依据。试验共分为四部分。1.象草青贮饲料中乳酸菌菌株的分离、鉴定本试验旨在从象草青贮饲料中分离、鉴定乳酸菌,为研究新的乳酸菌菌株和筛选潜在的优良乳酸菌菌株奠定基础。象草（Pennisetum purpureum）种植在中国江苏省南京农业大学实验田（北纬32°01′19″,东经118°51′08″,海拔17 m）。从小型发酵系统制备的象草青贮饲料中分离出176株产乳酸菌株,并基于形态学,生理学和生物化学特性以及16S rRNA分析鉴定了 7株这些菌株。结果表明,所有这7株分离乳酸菌菌菌均为同型发酵乳酸菌,并且能够在pH 3.5环境下生... 

【文章来源】：南京农业大学江苏省211工程院校教育部直属院校

【文章页数】：122 页

【学位级别】：博士

【文章目录】：
摘要
ABSTRACT
LIST OF ABBREVIATIONS
CHAPTER-1 INTRODUCTION
    1.1.Background
    1.2.General characteristics of tropical grasses
    1.3.Potential grasses for tropical silage making
        1.3.1 Elephant grass(Pennisetum purpureum)
        1.3.2 Sorghum(sorghum bicolor)
    1.4.Principles of ensiling
    1.5.Characteristics of grasses affecting the fermentation quality of silage
    1.6.Silage fermentation processes
        1.6.1.Aerobic phase
        1.6.2.Fermentation phase
        1.6.3.Stable phase
        1.6.4.Feed-out Phase/ aerobic spoilage phase
    1.7.Factors affecting the ensiling process
        1.7.1.grasses
        1.7.2.Grass dry matter
        1.7.3.Buffering capacity of grass
        1.7.4.Mechanical treatments of grasses
        1.7.5.Density
    1.8.Micro-organisms involved in the ensiling process
        1.8.1 LAB and their effects on the fermentation quality of silage
        1.8.2 Obligate heterofermentative LAB
        1.8.3 Enterobacteria
        1.8.4 Clostridia
        1.8.5 Fungi
        1.8.6 Bacilli
    1.9.Isolation and screening of lactic acid bacteria
    1.10.Physiology of lactic acid bacteria
    1.11.Phenotypic characterization
    1.12.Genotypic characterization
    1.13.Aerobic stability test
        1.13.1.Microbial,chemical and physical changes during aerobic exposure
        1.13.2.Effect of aerobic spoilage on silage quality
        1.13.3.Effect of homofermentative Lactic acid bacteria on aerobic stability
    1.14 Effect of heterofermentative LAB on aerobic stability
    1.15.Objectives of the study
CHAPTER-2 Isolation and characterization of LAB strains from elephant grass
    1.Introduction
    2.Material and methods
        2.1.Isolation of LAB from elephant grass silage
        2.2.Morphological and physiological tests of LAB
        2.3.Extraction of lactic acid bacteria genomic DNA
        2.4.Sequence alignments and phylogenetic implications
        2.5.Storage of LAB isolates
    3.Results
        3.1.The morphological and physiological properties of characteristic strains isolates
        3.2.16S rRNA gene sequence analysis
        3.3.Amplification products obtained from the recA gene multiplex assay
    4.Discussion
    5.Conclusion
Chapter-3 Effect of lactic acid bacteria isolates on the fermentation quality of elephantgrass during ensiling
    1.Introduction
    2.Material and methods
        2.1.Silage preparation
        2.2.Chemical analyses
        2.3.Microbial population
        2.4.Statistical analyses
    3.Result
        3.1.Characteristics of elephant grass
        3.2.Effect of LAB isolates on pH,DM,WSC and NH3-N of elephant grass duringensiling
        3.3.Effect of LAB isolates on the organic acids of elephant grass during ensiling
        3.4.Effect of LAB isolates on microbiological composition of elephant grass duringensiling
    4.Discussion
        4.1.Microbiological composition
    5.Conclusion
Chapter-4 Effects of lactic acid bacteria isolates on the fermentation quality of sweetsorghum silage during ensiling
    1.Introduction
    2.Material and methods
        2.1.Forage harvesting
        2.2.Silage preparation
        2.3.Chemical analyses
        2.4.Microbial population
        2.5.Statistical analyses
    3.Result
        3.1.Characteristic of sweet sorghum
        3.2.Effect of LAB isolates on fermentation quality of sweet sorghum during ensiling
        3.3.Effect of LAB isolates on organic acids of sweet sorghum during ensiling
        3.4.Effect of LAB isolates on microbiological compositions of sweet sorghum silageduring ensiling
        3.5.Fermentation quality of sweet sorghum silages after 90 days of ensiling
    4.Discussion
    5.Conclusions
Chapter-5 Effects of LAB on the fermentation quality and aerobic stability of elephantgrass silage during ensiling
    1.Introduction
    2.Material and methods
        2.1.Forage harvesting
        2.2.Silage preparation
        2.3.Aerobic stability
        2.4.Chemical analyses
        2.5.Microbial population
        2.6.Statistical analyses
    3.Results
        3.1.Characteristic of elephant grass
        3.2.Effect of LAB isolates on fermentation quality of elephant grass
        3.3.Effects of LAB isolates on organic acids of elephant grass silage during ensiling
        3.4.Fermentation quality of elephant grass silages after 90 days
        3.5.Effect of LAB isolates on microbiological compositions
        3.6 Aerobic stability of elephant grass silage
            3.6.1 Effect of LAB isolates on organic acids composition of elephant grass silageduring aerobic exposure
            3.6.2.Effect of LAB isolates on fermenation quality of elephant grass silage duringaerobic exposure
    4.Discussion
        4.1.Aerobic stability of elephant grass silage
    5.Conclusion
CONCLUSION
RECOMMENDATIONS AND SCOPE FOR FURTHER RESEARCH
INNOVATION
REFERENCES
APPENDICES
ACKNOWLEDGEMENTS
LIST OF PUBLICATIONS


【参考文献】：
期刊论文
[1]The Effect of Microbial Inoculants Applied at Ensiling on Sorghum Silage Characteristics and Aerobic Stability[J]. Ashbell G,Weinberg Z G.  Agricultural Sciences in China. 2002(10)



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