1 1
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
In the first chapter, we introduced a general outline on what will be of this subject. Now we start to examine details of microorganisms. Let’s see what microorganisms look like and what are made of.
1 2
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Chapter 2Structure of Bacteria
1 3
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Macromolecules ( 大分子 )
protein, polysaccharide, lipids, DNA, RNA, 96% (dw%)
Monomers: ( 单体及前体 )
amino acids and precursors, sugars and precursors 3%
Inorganic ions:
K+, Mg+2, Ca2+, Fe2+, Mn2+, Cu2+ 、 Co2+ 、 Zn+2……1%
Chemical compositionof a prokaryotic cell
2.1
1 4
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
O
C C
C C
Base
H
H or OH
H H
H
H
CH2OP
OH
O
HO
Sugar:
• RNA – ribose (OH)
• DNA – deoxyribose (H)
MacromoleculesNucleoside: base + sugar Bases:
adenine (A), cytosine (C),
guanine (G), thymine (T)
RNA uses uracil (U)
instead of thymine
Remember that carbon in sugar is numbered in sequence!!! How they are numbered?
1 5
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
C 胞嘧啶U 尿嘧啶
T 胸腺嘧啶
G 鸟嘌呤 A 腺嘌呤
图 1c 核糖 图 1b 核苷酸
1 6
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
A
T C
G
Question: if a cell DNA contains more G+C than A+T, is it harder or easier to separate two complementary chains?
Hydrogen bond
1 7
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
chains complementary to each other
1 8
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
氨基酸一般结构
肽 键
Macromolecules
protein
1 9
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC 2.2 Size and shape
of Bacteria• Average bacteria 0.5 - 2.0 um in diam.
• Surface area ~12 µm2
• Volume is ~4 µm
• Surface area to volume is 3:1
• Typical eukaryote cell SA/Vol is 0.3:1
• Food enters through SA, quickly reaches all parts of bacteria
• Eukaroytes need structures & organelles
1 10
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Approximate size of micro-organisms compared to a typical eukaryotic cell.
1 11
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC There are two types of cells:
prokaryotic vs. eukaryotic
1 12
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Shapes of Bacteria• Coccus ( 球菌 )
– Chain = Streptoccus– Cluster = Staphylococcus
• Bacillus ( 杆菌 )– Chain = Streptobacillus
• Coccobacillus ( 短杆菌 )• Vibrio = curved ( 弧菌 )• Spirillum ( 螺旋菌 )• Spirochete ( 螺旋体 )• Square ( 方形 )• Star ( 星形 )
1 13
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Streptococci ( 链球菌 ) showing dividing manner
1 14
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Tetradococci ( 四叠球菌 )
1 15
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Staphylococci ( 葡萄球菌 )
1 16
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC 球菌 (coccus) 的分裂方式
于群体形态之间的关系
沿着同一平面分裂;分裂后两个细胞连在一起的称为双球菌 (Diplococcus)
沿着两个相互垂直的平面分裂;四个细胞连在一起的称为四联球菌 (Tetrads)
沿着三个平面分裂;子细胞聚集在一起的称为葡萄球菌 (Staphylococcus)
细胞沿三个互相垂直的面分裂,分裂后每八个细胞特征性地叠在一起呈一立方体的称为八叠球菌 (Sarcinalutea)
沿着同一平面分裂;分裂后两个以上细胞连在一起的称为链球菌 (Streptococcus)
单球菌 (Coccus)
1 17
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Square cell: Cyanobacteria
1 18
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
2.3 Bacterial Structures
1 19
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Flagella ( 鞭毛 )• Motility - movement• Swarming ( 聚集 ) occurs with some bacteria
– Spread across Petri Dish– Proteus ( 多变的 ) species most evident
• Arrangement basis for classification– Monotrichous ( 单身鞭毛 ); 1 flagella– Lophotrichous ( 丛生鞭毛 ); tuft at one end– Amphitrichous ( 端生鞭毛 ); both ends– Peritrichous( 周身鞭毛 ); all around bacteria
• Observe Picture in Micro Lab.
1 20
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 21
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 22
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 23
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Pili ( 纤
毛 )• Short protein appendages– smaller than flagella
• Adhere bacteria to surfaces– E. coli has numerous types
• K88, K99, F41, etc.– Antibodies to will block adherance
• F-pilus; used in conjugation– Exchange of genetic information
• Flotation; increase boyancy– Pellicle (scum on water)– More oxygen on surface
1 24
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
F-Pilus for Conjugation (结合)
1 25
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Capsule or Slime L
ayer (荚膜 / 粘液)
• Glycocalyx ( 多糖 )- Polysaccharide on external surface• Adhere bacteria to surface• Prevents phagocytosis( 嗜菌作用 )• Prevent water from loss
1 26
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Cytoplasm (细胞质)
• 80% Water by weight, 20% salts-proteins– Osmotic ( 渗透压 ) shock important
• DNA is circular( 环状 DNA), haploid ( 单链 )– More efficient; grows quicker– Mutations ( 变异 ) allow adaptation to environ
ment quicker• Plasmids ( 质粒 ); circular DNA independent to chr
omosome ( 独立于染色体的环状 DNA);• Antibiotic resistance ( 抗 抗生素 ) • No organelles 细胞器 (mitochondria, Golgi, etc.)
The part inside the membrane
1 27
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Cell Membrane (细胞膜)
• Bilayer phospholipid• Water can penetrate• Flexible• Not strong, ruptures ( 断裂 ) easily
– Osmotic pressure created by cytoplasm
磷脂的化学结构 ( 左 ) 及其示意图 ( 右 )
亲水端
疏水端
亲水端疏水端
1 28
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
亲水端
疏水端
脂肪酸
甘油
1 29
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
嵌入蛋白 磷脂
1 30
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC 醣蛋白 醣脂类
固醇
1 31
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
真菌和古细菌质膜中磷脂组成的区别
Differences of membrane lipids between Archaea and other organisms
细菌和真菌
古细菌
细菌和真菌的质膜由无分支的直链脂肪酸通过酯键与甘油连接;
古细菌则由带有支链脂肪酸与甘油连接。
酯键
醚键
Branches
1 32
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Cell Wall
• Peptido-glycan ( 肽 - 糖 ) polymer (amino acids + sugars)
• Unique ( 特别 ) to bacteria
• Sugars; NAG & NAM
– N-acetylglucosamine (N- 乙酰氨基葡萄糖 )
– N-acetymuramic acid (N- 乙酰胞壁酸 )
• D form of Amino acids used not L form
– Hard to break down D form
• Amino acids cross link NAG & NAM
1 33
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 34
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
D- 丙氨酸
D- 谷氨酸间二氨基庚二酸
L- 丙氨酸
图 20 肽聚糖的亚单位
NAG : N- 乙酰葡萄糖胺
NAM : N- 乙酰胞壁酸
氨基
糖
氨基酸
1 35
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Cell wall structure of Gram negative bacteria G- 细菌细胞壁结构
细胞质
胞围
细胞膜
肽聚糖 外膜
1 36
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
裂解酶敏感键
1 37
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 38
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
生长点
胞内合成前体,通过膜运送到胞外合成薄壁
1 39
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
外膜
内膜
1 40
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Cell wall structure of Gram positive bacteria
革兰氏阳性菌 (G+)的细胞壁
1 41
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Cell Wall Summary
• Determine shape of bacteria
• Strength prevents osmotic rupture
• 20-40% of bacteria
• Unique to bacteria
• Some antibiotics effect directly
– Penicillin
1 42
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Cell Wall
Teichoic Acids 磷壁 ( 酸 ) 质
• Gram+ only
• Glycerol, Phosphates, & Ribitol
• Attachment for Phages
1 43
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 44
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Lipopolysaccharide (LPS)• Endotoxin or Pyrogen
– Fever causing– Toxin nomenclature
• Endo- part of bacteria• Exo- excreted into environment
• Structure– Lipid A– Polysaccharide
• O Antigen of E. coli, Salmonella• G- bacteria only
– Alcohol/Acetone removes
1 45
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 46
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
1 47
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC LPS (cont’d)
• Functions– Toxic; kills mice, pigs, humans
• G- septicemia; death due to LPS– Pyrogen; causes fever
• DPT vaccination always causes fevers– Adjuvant; stimulates immunity
• Heat Resistant; hard to remove• Detection (all topical & IV products)
– Rabbits (measure fever)– Horse shoe crab (Amoebocytes Lyse in prese
nce of LPS)
1 48
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC LPS (cont’d.)
• Appearance of Colonies
– Mucoid = Smooth (lots of LPS or capsule)
– Dry = Rough (little LPS or capsule)
• O Antigen of Salmonella and E. coli
– 2,000 different O Ags of Salmonella
– 100’s different O Ags of E. coli
• E. coli O157
• O Ags differ in Sugars, not Lipid A
1 49
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRCEndospores( 芽孢、内生芽
孢 )• Resistant structure
– Heat, irradiation, cold
– Boiling >1 hr still viable
• Takes time and energy to make spores
• Location important in classification
– Central, Subterminal, Terminal
• Bacillus stearothermophilus( 强耐高温 ) -spores
– Used for quality control of heat sterilization equipment
• Bacillus anthracis - spores
– Used in biological warfare
1 50
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Bacillus anthracis( 炭疽热细菌 ). Gram stain. The cells have characteristic squared ends( 端齐 ). The endospores are ellipsoidal( 椭圆 ) shaped and located centrally in the sporangium. The spores are highly refractile ( 折射 ) to light and resistant to staining.
1 51
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC Bacillus thuringiensis. Phase Photomicrograph
of vegetative cells, intracellular spores (light) and parasporal crystals (dark) ( 类芽孢晶体 ) .
1 52
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC G+ vs. G-
• G+
– Thicker cell wall
– Teichoic Acids
• G-
– Endotoxin - LPS
• Which are more sensitive to Penicllin?
• Alcohol/Acetone affects which more?
1 53
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Prokaryotes vs. Eukaryotes• Cell Wall
• Teichoic Acids
• LPS
• Endospores
• Circular DNA
• Plasmids
1 54
Shixue Yin (Prof Dr)Microbiology SectionCESE, YZU, 225009 PRC
Eukaryote Cell Structure