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1896 1920 1987 2006
Lecture 2
An Overview of Microbial
Life
Zhao Liping, Chen Feng
School of Life Science and Technology
Shanghai Jiao Tong University
http://micro.sjtu.edu.cn
Chapter 2 inBROCK BIOLOGY OF MICROORGANISMS
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I. Cell Structure and Evolutionary
History
Most of the microbial cells are prokaryotic cells原核
细胞
Some microorganisms have eukaryotic cell structure
真核细胞
Some microorganisms are non-cellular life forms非细
胞生物
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2.1 Elements of Cell and Viral Structures
Internal structure of microbial cells. Prokaryote cells lack a true
nucleus and organelles原核细胞无真正的细胞核及细胞器
Eukaryote cell possesses a true nucleus and organelles
真核生物具有细胞核及细胞器
Eukaryotic cells真核
Algae藻类
Fungi真菌
Molds丝状真菌
Yeasts
Protozoa原生生物
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Non-cellular life forms: virus 病毒
A single virus particle is about 65nm in diameter.
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Nucleoid : aggregated DNA /bacterial chromosome
in the prokaryotic cell 类核:用于描述原核细胞中
聚集在一起的DNA
2.2 Arrangement of DNA in Microbial
Cells: Bacterial Nucleoid
By gently lysing the cells, the highly compacted
nucleoid will emerge intact. 采用极轻微小心的细胞
裂解方法,就可以得到一团完整展开的类核DNA。
(Arrows
point to edge
of strands).
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Bacteria contain one long circular DNA-
chromosome. 细菌的类核包含一条环状的DNA
(染色体)
The DNA can be 1mm long
The cell is usually 2-3m long
The DNA in both the open circle and supercoiled chromosome is
present in a covalently closed form. 超螺旋
The double-stranded DNA in E. coli chromosome contains over
50 supercoiled domains.超螺旋域
Genome sizes vary greatly ranging from viruses with the
smallest to algae and vertebrates possessing the
greatest amount.病毒基因组最小,藻类、脊椎动物最大
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2.3 Tree of Life
Evolution is the change in a line of descent over
time leading to new species or varieties.演化/进化
Evolutionary relationships between life forms are
the subject of phylogeny.系统发生学
Phylogenetic relationships can be deduced by
comparing sequences of certain macromolecules
(ribosomal RNAs).
Ribosomal RNA gene sequencing and phylogeny.
(a) Cells, either from a pure culture or from an environmental sample, are broken open;(b) the gene-encoding ribosomal RNA is isolated, and many identical copies
made by polymerase chain reaction (PCR)(c) The gene is sequenced(d) the sequences obtained are aligned in a computer.
(e) An algorithm makes a tree that shows the differences in rRNA sequence
between the organisms analyzed. 对比不同生物之间rRNA的差异,可得到描述其两两差异的树状结构.
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Phylogenetic tree of life as defined by comparative ribosomal
RNA sequencing. three domains of organisms: the bacteria and the
Archaea, cells of which are prokaryotic, and the Eukarya (eukaryotes).三域:
细菌, 古生菌与真核生物.
1896 1920 1987 2006
PART II Microbial Diversity
2.4 Physiological Diversity of Microorganisms
微生物的生理多样性
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All cells need carbon and
energy sources.
Chemoorganotrophs obtain
their energy from the
oxidation of organic
compounds.化能有机营养型.
Chemolithotrophs obtain
their energy from the
oxidation of inorganic
compounds.化能无机营养型
Phototrophs contain
pigments that allow them to
use light as an energy source.
光能营养型
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Autotrophs and heterotrophs
Autotrophs use CO2 as their carbon source, whereas
heterotrophs use organic carbon. 自养型生物以CO2
为碳源, 异养型生物以有机碳为碳源.
Depend on the carbon source.
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2.5 Prokaryotic Diversity
Several lineages are present in the domains
Bacteria and Archaea, and an enormous diversity of
cell morphologies and physiologies are represented
there. 细胞形态及生理的多样性
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Microbial cells: Bacteria
Pathogens
Soils, water, animal intestine, etc
Different energy sources, carbon sources, oxygen
demands
Detailed phylogenetics tree of Bacteria
产液菌属
栖热袍菌属
无硫绿细菌
异常球菌
螺旋体绿硫细菌
浮霉状菌属
蓝细菌
变形杆菌
革兰氏阳性细菌
Proteobacteria: the largest
division (called a phylum门) of
Bacteria.变形杆菌
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Cyanobacteria蓝细菌
The Cyanobacteria are phylogenetic relatives
of gram-positive bacteria and are oxygenic
phototrophs.
Filamentous cyanobacteria 丝状蓝细菌
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Microbial cells: Archaea
Many are extremephiles, anerobic
• Boiling-hot spring
• Freezing-Antarctic ocean
• Radioactive wastes
• Salty, acidic, alkaline soils or water
They can be found almost anywhere on earth
There are two lineages of Archaea, the Euryarchaeota and the
Crenarchaeota. 古生菌有广古生菌界与泉古生菌界.
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Molds
Mushrooms Fungi
Yeasts
Slime molds
Algae
Protozoa
2.6 Eukaryotic Microorganisms
Cells of algae and fungi have cell walls, whereas the protozoa do not.
Fungi are heterotrophic eukaryotic microorganisms.
They are nonphotosynthetic and typically form
reproductive spores.真菌为异养真核生物,非光合,一般可形成繁殖的孢子.
Algae are phototrophic eukaryotes that contain
photosynthetic pigments within chloroplast藻类是光合真核生物,在其叶绿体中有光合色素.
Protozoa are animallike protists exhibiting
heterotrophic nutrition and they can be defined as
usually motile eukaryotic unicellular microorganisms.
原生生物是类似动物的低等异养真核生物, 常定义为可运动的单细胞真核微生物.
Detailed phylogenetic tree of Eukarya
双滴虫 微孢子虫
鞭毛虫
粘质霉菌
硅藻
褐藻
纤毛虫
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Algae 藻类 Fungi 真菌
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Protozoa 原生生物
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a)Amoeba变形虫
b)A typical ciliate典型的纤毛虫
c) A flagellate鞭毛虫
Some algae and fungi have developed mutualistic associations
called lichens. 一些藻类与真菌共生而形成地衣
Some algae and fungi have developed mutualistic associations
called lichens. 一些藻类与真菌共生而形成地衣
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Discussion
What kinds of organisms belong to the
Microorganisms?
Different between mould, cyanobacteria and
algae?
Different between yeast, mould and mushroom?
Different between protozoa, yeast and animal?
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