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General Microbiology Group 1 Chimi Seldon Dorji Sangay Wangmo Tek Bahadur Powdel Sang Dorji Tamang Hem Raj Subba Norbu ( 14/04/2010)

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Presentation on theme: "General Microbiology Group 1 Chimi Seldon Dorji Sangay Wangmo Tek Bahadur Powdel Sang Dorji Tamang Hem Raj Subba Norbu ( 14/04/2010)"— Presentation transcript:

1 General Microbiology Group 1 Chimi Seldon Dorji Sangay Wangmo Tek Bahadur Powdel Sang Dorji Tamang Hem Raj Subba Norbu ( 14/04/2010)

2 Definition Study of living organism of microscopic size Eg.:Bacteria, fungi, algae, protozoa, and the infectious agents called viruses. Concerned with their form, structure, reproduction, physiology, metabolism and classification Study of their distribution in nature, relationship to each other and to other living organisms, effects on human beings, animals and plants

3 Micro-organisms Some are beneficial while others are detrimental Example: Some micro-organisms are involved in making of yogurt, cheese and wine, in production of penicillin, interferon and alcohol, processing of domestic and industrial wastes On the other hand they can cause disease, spoil food and deteriorate materials like iron pipes, glass lenses and wood pilings. Unicellular and multi cellular Single cell performs all the life processes higher organisms are composed of many cells arranged in tissues and organs that perform specific functions

4 CharacteristicsDescription Morphological Characterisics  Study of individual cells of a pure culture  Size expressed in micrometers (µm)  1 µm=.001mm= in  Examination requires use of a high power microscope (1000 diameters) Chemical Characteristics  M.Cells contain variety of organic compounds  characteristic chemical composition  qualitative and quantitative differences in composition among species Eg. Lipopolysaccharide is present in Gram negative bacteria and not in Gram positive bacteria, algal and fungal cell wall are different from those of bacteria, viruses are distinguished by RNA and DNA Characteristics of Microorganisms

5 CharacteristicsDescription Cultural Characteristics  Specific growth requirements; culture medium,medium containing inorganic and organic compounds, natural substances,some can be propogated only in living host or living cells,  some grow at temp. above 40ºC,some cannot grow above 20ºC,some at 37ºC, some need O 2 while others dont need it, bacteria like cyanobacteria require light while growth is inhibited by light in some others Metabolic Characteristics  Life processes involves complex chemcal reactions- metabolism, obtain energy by absorbing light or by oxidizing various organic and inorganic substances.

6 CharacteristicsDescription Antigenic Characteristics  Chemical compounds - antigens  Blood serum proteins, antibodies respond to antigens Genetic Characteristics DNA base composition The sequence of nucleotide bases in the DNA Pathogenicity Ability to cause the disease Ecological Characteristics Habitat is important in characterizing organisms Eg. Marine Vs freshwater Oral cavity Vs intestinal tract

7 Branches of Microbiology 1.Bacteria 2.Virus 3.Fungi: Molds 4.Fungi: Yeasts 5.Protozoa 6.Algae

8 (1) Bacteria (2) Viruses

9 (3) Fungi: Molds (4) Fungi: Yeasts

10 (5) Protozoa (6) Algae

11 Branches Size Important CharacteristicsPractical Significance Bacteria μm prokaryotic, unicellular, simple internal structure, grow on artificial laboratory media, asexual reproduction by simple cell division some cause disease, some help in natural cycling of elements, manufacture of compounds spoils and makes food Viruses μm don’t grow in laboratory media, requires living cells for reproduction, obligate parasites, electron microscope to see it cause diseases in human, plants, animals and infect other microorganisms Fungi: Molds μmEukaryotic, multi cellular can be cultivated in the laboratory, reproduction by sexual and asexual processes. decomposition, industrial production of chemicals, penicillin, causes diseases in humans, plants & animals

12 BranchesSizeImportant CharacteristicsPractical Significance Fungi: Yeasts5.0-10μm Eukaryotic, unicellular, cultivated in laboratory, reproduction by sexual, asexual and budding processes alcoholic beverages, food supplement, cause disease Protozoa μm Eukaryotic, unicellular, cultivated in laboratory, reproduction by sexual and asexual processes, parasites food for aquatic animals, some cause disease Algae1.0μm- many feet Eukaryotic, unicellular & multicellular, aquatic, chlorophyll, reproduction by sexual and asexual processes production of food in aquatic environment, medicines, food supplement, source of agar, toxic substance production

13 Microbial Classification Classification bringing order to the bewildering variety of organism in nature. Pure culture- a population of micro-organism a culture consist of single kind of micro organism(one living species), regardless of the number of individuals, in an environment free of other living organism is called pure culture.

14 Classification (1) Virus The Baltimore classification Classification of virus into families depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded (ds) etc.) and their method of replication. (2)Bacteria shape, either gram positive or gram negative, based on whether they take up the gram stain that is commonly used to make them easier to see under the microscope. live in the presence of oxygen (aerobic) or require the absence of oxygen (anaerobic).

15 Gram Positive Bacteria (e.g., Staphylococcus aureus) The walls of gram positive bacteria have more peptidoglycans (the large molecular network of repeating disaccharides attached to chains of four or five amino acids) than do gram-negative bacteria. Thus, gram-positive bacteria retain the original violet dye and cannot be counterstained. Gram Negative Bacteria(e.g., Escherichia coli ) have thinner walls, containing an outer layer of lipopolysaccharide, which is disrupted by the alcohol wash. This permits the original dye to escape, allowing the cell to take up the second dye, or counterstain. Thus, gram- positive bacteria stain violet, and gram-negative bacteria stain pink.

16 Gram Positive Bacteria Cell ShapeCharacteristicsGenusFamily Cocci cells in irregular clusters staphylococcus Micrococcus Sarcina Micrococcaceae Cells in chains Streptococcus Leuconostoc Streptococcaceae BacilliAerobic SporingBacillusBacillaeceae Anaerobic SporingClostridium Lactic fermentationLactobacillusLactobacillacaeae Propionic fermentation PropionibacteriumPropioni- bacteriaceae

17 Cell ShapeCharacteristicsGenusFamily Oxidative, weakly fermentative Corynebacterium Listeria Erysipelothrix

18 Cell ShapeCharacteristicsGenusFamily CocciAerobic Neisseria Veilonella Neisseriaceae Coccobacilli Brucella, Bordetella Pasteurella Haemophilus Brucellaceae BacilliFacultative anaerobic, motile with peritrichous flagella or immotile Escherichia, Shigella, Salmonella, Proteus, Erwinia, Yersinia, Enterobacter, Serratia Entero- bacteriaceae Gram Negative Bacteria

19 Cell ShapeCharacteristicsGenusFamily Aerobic, motile with peritrichous flagella or immobile Azotobacter Rhizobium Azotobacteraceae Rhizobiaceae Aerobic, motile with polar flagella Nitrosomonas, Nitrobacter, Thiobacillus Nitrobacteraceae Pseudomonas, acetobacter, legionella Pseudomona- daceae Facultative anaerobic with polar flagella Campylobacter, Zymomonas, Aeromonas Curved rods with polar flagella Vibrio, Spirillum, Desulfovibrio Spirillaceae

20 Main Requirements for bacterial culture 1.Moisture 2.Warmth and Temperature 3.Time 4.pH level 5.Oxygen 6.Competition How to grow/culture bacteria? Things required Agar Cooking thermometer Small cooking pot Petri dishes Sterile cotton swabs Warm dark cupboard Book on bacteria cultures

21 Step 1 Mix the agar according to the manufacturer's instructions. Agar is a bit like Jell-o and the ingredients will need to be heated to precise temperatures. Make certain that you have a clean cooking thermometer handy. Step 2 Open a petri dish and pour just enough agar into the dish to cover the bottom completely. Put the lid back on immediately and set the dish aside until the agar firms. Fill each dish the same way, never leaving the top of the dish off any longer than absolutely necessary. Once the agar hardens you may store the dishes in the refrigerator upside down to avoid the possibility of any airborne bacteria getting into the dishes. Step 3 Remove the petri dishes from the refrigerator only when you are ready to use them. Open your sterile cotton swab package and rub the cotton swab on a surface you wish to test for bacteria, such as a countertop. Open a petri dish and rub your swab gently across the surface of the agar in an "S" pattern. Close the lid on the petri dish.

22 Step 4 Set the dish in a warm dark cupboard for three to four days Step 5 Remove the dish from the cupboard. There is no need to open the dish. Observe the bacteria colonies through the top of the dish. Record their color, shape and anything else distinguishing. Look in a bacteria book or on the Internet for illustrations that match the bacteria you have cultured. Step 6 Destroy your cultured bacteria once you have identified it. Pour 1 tbsp. of bleach into the petri dish and then seal the dish closed with packing tape, put the dish in a baggie, seal it and throw away.

23 Scope of Microbiology 1.Medical biology Causative agents of disease; diagnostic procedures; diagnostic procedures for identification of causative agents, preventive measures 2.Aquatic Microbiology Water purification, microbiological examination, biological degradation of waste,ecology 3.Aeromicrobiology Contamination and soilage; dissemination of diseases 4.Food microbiology Food preservation and preparation; foodborne diseases and their prevention

24 5.Agricultural microbiology Soil fertility, plant and animal diseases 6.Industrial microbiology Producton of medicinal products such as antibodies and vaccines; fermented beverages; industrial chemicals, production of proteins and hormones by genetically engineered microorganisms. 7.Exomicrobiology Exploration for life in the outer space 8.Geochemical microbiology Coal, mineral and gas formation; prospecting for deposits of coal, oil, and gas; recovery of minerals from low-grade ores


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