1 Micro-Organisms Morphology.ppt [Read-Only]Micro-organisms • Study of organisms tooStudy of...
Transcript of 1 Micro-Organisms Morphology.ppt [Read-Only]Micro-organisms • Study of organisms tooStudy of...
Micro organismsMicro-organisms
• Study of organisms too• Study of organisms too small to be clearly seen by the unaided eye (i.e., micro-organisms)
• Size < ~1 mm (microscopic organisms)
• Mainly single-celled organisms
• Lack organs and true tissue
• Some multi-celled organisms have primitive tissues
V h t• Very heterogeneous group
Micro organismsMicro-organismsCan be divided into:
Procaryotes (lack a true membrane-delimited nucleus)
1. archaea or archaeobacteria2. bacteria or eubacteria
--------------------------------Eucaryotes (have a membrane-enclosed nucleus, are more complex morphologically and aremorphologically and are usually larger than procaryotic cells)
3 algae Eukaryotes have organelles!3. algae4. fungi5. protozoa
--------------------------------
6. viruses (obligate parasites)
Examples of the importance of micro-organisms
• The oldest and most common form of• The oldest and most common form of life
• Mineralization (biogeochemical c cles bioremediation compostingcycles, bioremediation, composting, water purification, etc.)
• Useful to macro-organisms (nitrogen fi i i i bi i lfixation, nutrition, symbiosis, normal flora, photosynthesis etc.)
• Biotechnical processes (food,
Fossilized bacteria
p ( ,pharmaceuticals, chemical products, etc.)
• Pathogenic micro-organismsPathogenic micro organisms (infectious diseases, product spoilage, etc.)
• Model systems in biology (genetics• Model systems in biology (genetics, physiology, metabolism, etc.)
The oldest and most common form of life
Earth4.5 billionyears old
3 5 billi3.5 billion
1.4 billion
The oldest and most common form of life
Mineralization (biogeochemical cycle, bio-remediation composting water purification etc )remediation, composting, water purification, etc.)
Useful to macro-organisms
Useful to macro-organisms
Biotechnical processes
Biotechnical processes
Pathogenic micro-organisms
Pathogenic micro-organismsPathogenic micro-organisms
The Nobel Prize in Medicine 2005
P th i i iPathogenic micro-organisms
Main morphological groups – Bacteria- size, appearance and cell arrangement
- two basic forms: cocci and bacilli
Bacilli or rods: CylindricalCocci: spherical cells 1 2 µm Bacilli or rods: Cylindricalshape, diam 1 µm, length2-5 µm
Cocci: spherical cells, ~1-2 µmin diam. Cell arrangement uponcell division:
- Coccobacilli: very shortbacilli, reminiscent of cocci
- Vibrions: a twisted
- Diplococci- Streptococci- Staphylococci
T t d Vibrions: a twistedbacillus, not a completespiral, 2-3 µm long
S i ill b illi l i id
- Tetrads- Sarcina
- Spirilla bacilli: long, rigid,spiral bacilli with flagellae,6-15 µm long
Exceptions
- Flat, quadratic bacteria:- Spirochet bacilli: long,flexible, spiral bacilli withan axial filament
, q0.25 x 2 x 2-4 µm
- Pleomorphic: no particular shape lack cell wall
- Hyphae that form a micelleshape, lack cell wall
Cocci: spherical cells, ~1-2 µm in diam.
Streptococcus pyogenes
Staphylococcus aureus
Bacilli or rods:Bacilli or rods:Cylindrical shape, diam 1 µm, length 2-5 µm
Escherichia coli Bacillus subtilis
Vibrions: a twisted bacillusVibrions: a twisted bacillus
Spirillaspiral bacilli with flagellae, 6-15 µm long
Spirochetspiral bacilli with an axial filament
Micelle-forming bacteriaMicelle-forming bacteria
The genus Streptomyces includes about 500 species.Constitutes 1-20% of the cultivable earth flora.Forms geosmin or earth smell and a large number of antibioticsForms geosmin, or earth smell, and a large number of antibiotics.
Bacterial staining methodsBacterial staining methods
• Aim:• Aim:To increase contrast in microscopy slides for the systematisation of bacteria
• Principle: - Basic (cationic) dyes, e.g. violet, methylene blue and malachite green
- Acidic (anionic) dyes, e.g. eosin and Congo red
- Fat-soluble dyes such as Sudan black
• Fixing: Heat or chemicals (formaldehyde, acetic acid or alcohol) are used to fix bacteria on slides in order to increase the penetration of the dye.
Bacterial staining methodsBacterial staining methods
G t i iGram staining: (Christian Gram, 1884)
• Heat fixing• Crystal violet
Lugol’s solution (KI + I )• Lugol s solution (KI + I2)• EtOH or acetone• Safranin (counterstain)
Gram-positive bacteria = blueGram-negative bacteria = redGram negative bacteria red