Download - General Microbiology
General MicrobiologyGroup 1
Chimi Seldon Dorji
Sangay Wangmo
Tek Bahadur Powdel
Sang Dorji Tamang
Hem Raj Subba
Norbu ( 14/04/2010)
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
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
Characteristics Description
Morphological
Characterisics
Study of individual cells of a pure culture
Size expressed in micrometers (µm)
1 µm=.001mm=.00004 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
Characteristics Description
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 O2 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.
Characteristics Description
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 organismsEg. Marine Vs freshwater Oral cavity Vs intestinal tract
Branches of Microbiology
1. Bacteria 2. Virus3. Fungi: Molds4. Fungi: Yeasts5. Protozoa6. Algae
(1) Bacteria
(2) Viruses
(3) Fungi: Molds
(4) Fungi: Yeasts
(5) Protozoa
(6) Algae
Branches Size Important Characteristics Practical Significance
Bacteria 0.5-1.5μm 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 0.015-.2μm 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
2.0-10μm Eukaryotic, 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
Branches Size Important Characteristics Practical Significance
Fungi: Yeasts 5.0-10μm Eukaryotic, unicellular, cultivated
in laboratory, reproduction by
sexual, asexual and budding
processes
alcoholic beverages, food
supplement, cause disease
Protozoa 2.0-200μm Eukaryotic, unicellular, cultivated
in laboratory, reproduction by
sexual and asexual processes,
parasites
food for aquatic animals,
some cause disease
Algae 1.0μm-
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
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.
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).
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.
Gram Positive Bacteria
Cell Shape Characteristics Genus Family
Cocci cells in irregular
clusters
staphylococcus
Micrococcus
Sarcina
Micrococcaceae
Cells in chains Streptococcus
Leuconostoc
Streptococcaceae
Bacilli Aerobic Sporing Bacillus Bacillaeceae
Anaerobic Sporing Clostridium
Lactic fermentation Lactobacillus Lactobacillacaeae
Propionic
fermentation
Propionibacterium Propioni-
bacteriaceae
Cell Shape Characteristics Genus Family
Oxidative,
weakly
fermentative
Corynebacterium
Listeria
Erysipelothrix
Cell Shape Characteristics Genus Family
Cocci Aerobic Neisseria
Veilonella
Neisseriaceae
Coccobacilli Brucella, Bordetella
Pasteurella
Haemophilus
Brucellaceae
Bacilli Facultative
anaerobic, motile
with peritrichous
flagella or
immotile
Escherichia,
Shigella,
Salmonella, Proteus,
Erwinia, Yersinia,
Enterobacter,
Serratia
Entero-
bacteriaceae
Gram Negative Bacteria
Cell Shape Characteristics Genus Family
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
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
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.
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.
Scope of Microbiology
1.Medical biologyCausative 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
5.Agricultural microbiology
Soil fertility, plant and animal diseases
6.Industrial microbiologyProducton of medicinal products such as antibodies and vaccines; fermented beverages; industrial chemicals, production of proteins and hormones by genetically engineered microorganisms.
7.ExomicrobiologyExploration for life in the outer space
8.Geochemical microbiologyCoal, mineral and gas formation; prospecting for deposits of coal, oil, and gas; recovery of minerals from low-grade ores