Selective culture media Culture media are the base where microorganisms can grow with the help of nutrients and under the influence of physical growth parameters. All microorganisms cannot grow in a single culture medium and in fact many cannot grow in any known culture medium. Some organisms cannot grow in artificial culture medium are known as obligate parasites. Examples: Mycobacterium leprae, Rickettsias, Chlamydias, Treponema pallidum. Selective culture media: These are specially designed culture medium made for special or any one bacteria. 1. Thayer Martin agar 2. Mannitol salt agar 3. Mac Conkey's agar 4. Lowenstein Jensen 5. Wilson and Blair agar 6. Crystal violet blood agar 7. Pseudosel agar
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Cultivation of Anaerobes Anaerobic microorganisms are widely spread in environment. They do not require oxygen for their growth. Sometimes these organisms are very toxic. There are three types of anaerobes namely, Facultative anaerobes, Obligate anaerobes and Aerotolerant anaerobes . Facultative anaerobes: They are the organisms that can grow in presence or absence of oxygen . They obtain energy by both respiration as well as fermentation. E.g.- Staphylococcus spp. Streptococcus spp., Escherichia coli, Salmonella, Listeria spp . and Shewanella oneidensis . Obligate anaerobes: They are the organisms that can grow totally in absence of oxygen . Oxygen is toxic for their normal growth. Examples: Actinomyces, Bacteroides, Clostridium, Fusobacterium, Peptostreptococcus, Porphyromonas, Prevotella, Propionibacterium, Veillonella etc. Aerotolerant anaerobes: They are the organisms that cannot use oxygen for growth but ...
Preservation methods for pure cultures Preservation is a process to maintain pure culture for extended periods in a viable condition without any genetic changes. Once a pure culture has been obtained from the mixture, the microbes may be maintained in the laboratory over long periods. The most important factor of preservation is to stop microbial growth or at least suppress the growth rate. Objectives of Preservation: • To maintain isolated pure cultures for longer periods in a viable conditions. • To avoid contamination. • To restrict genetic changes. Several techniques are used to preserve cultures: Subculturing: In this method, nutrients of culture medium is regularly changed. So, culture media should be pure. Nutrient agar medium is commonly used where most of the heterotrophs remain viable for several months. Paraffin method: In this method, paraffin oil added in the culture media, which inhibit the growth of bacteria, because it forms a thin l...
Isolation and Preservation methods for Pure Culture Mix Culture Media: A Culture media, which contain more than one kind of microorganism is called a mixed culture media. Pure Culture: A pure culture is usually derived from a mixed culture by transferring a small sample into new. _ Pure culture is defined as a laboratory culture containing a single species of organism. Importance of Pure Culture: a] Desired known species of microorganisms can grow once pure culture is isolated. b] Pure culture can be correctly identified for accurate study and testing of microorganism in a clinical environment. c] Experimenting with pure culture ensures the same results after repetition of experiment many times. d] In pure culture, the spontaneous mutation rate is low. Isolation : Isolation is the separating process of particular microorganism from the mixed culture. Methods of isolation for pure culture: 1] Streak plate method 2] Pour plate method 3] ...
Bacterial Growth Curve Definition: When a graph plotted between the growth of bacteria and time page is called growth curve. Phases of bacterial growth curve-- Bacterial growth curve has four distinct phases Lag phase Log phase Stationary phase Decline phase Lag Phase: In this phase there are no growth of bacteria, because culture media is just prepared, so up to 2 to 3 hours there are no growth of bacteria, only nutrition medium present. During that time, necessary enzymes and intermediate metabolites are synthesized and before multiplication the bacterium reaches a critical stage and finally multiplication takes place at this stage. Hence, this stage is also known as initial stage or dormant stage. Log Phase: In this phase, there are maximum growth of bacteria because after the germination of bacteria they reproduce in fast rate and bacteria increases. And there are nutrition is more than the bacteria, so bacteria grow maximum. -- Also called as Exponential...
Physical parameters for growth of Bacteria Some of the important factors affecting bacterial growth are: 1. Temperature 2. Gaseous requirement 3. pH 4. Ions and salt concentration [Osmotic pressure] 5. Water Temperature: Minimum Growth temperature: T he lowest temperature at which microbes shows their growth is called minimum growth temperature. Below minimum temperature cell membrane solidifies and become stiff to transport nutrients in to the cell, hence no growth occurs Maximum growth temperature: T he highest temperature at which microbes shows their growth is known as maximum growth temperature. There is no growth below minimum and above maximum temperature. Optimum growth temperature: T hat temperature at which bacteria grows rapidly and maximum, is called optimum growth temperature. Based on temperature they are classified-- 1] Psychrophiles (0 - 15 degree C) 2] Mesophiles (20 - 40 degree C) 3] Thermophiles (45- 7...
Raw materials used for culture media Raw materials play an important role in media preparation. Quality of media depends on the quality of raw materials. The most important raw materials are used for preparations of media are-- water, agar, peptone, casein hydrolysate, meat extract, yeast extract and malt extract. 1. Water as solvent: Water plays a vital role in preparation of media. Water should be free from copper ion because copper ion inhibits the growth of the microorganisms. Conductivity of water should be less than 15 µS (microsiemens) and the pH of the water should be slightly acidic but should not be less than 5.5. 2. Petri dishes : Petri dishes are generally sterilized with ethylene oxide (EtO) or gamma irradiated. Only borosilicate glassware should be used because soda glass can leach alkali into the media. 3. Energy source: The most common substance added to culture media is glucose that acts as source of energy and also increa...
Nutrition required for Bacterial Culture Medium Most of the microorganisms are grown in specific culture media in laboratory conditions and for proper growth nutrition plays an important role for structural and functional properties of the cells. Nutrition are generally composed of: • Major macronutrients: C, H, O, N, S, P, K, Mg, Fe, Ca and Mn. • Major micronutrients: Zn, Co, Cu, and Mo. • Mineral Sources • Carbon and energy sources. • Growth factors. • Vitamins. Major Macronutrients: • Carbon: The main source is organic compounds and CO2. It is the main component of cellular materials. • Hydrogen: The main source is organic compounds. It is the main component of cell water. • Oxygen: The main source is organic compounds, CO2 and O2. It is the main constituent of cell material and cell water. It is electron acceptor in aerobic respiration. • Nitrogen: The main source is organic compounds, NH3, NO3, N2 etc. It is the ma...
Culture media: Culture media are the base where microorganisms can grow with the help of nutrients and under the influence of physical growth parameters. All microorganisms cannot grow in a single culture medium and in fact many cannot grow in any known culture medium. Some organisms cannot grow in artificial culture medium are known as obligate parasites. Examples: Mycobacterium leprae, Rickettsias, Chlamydias, Treponema pallidum. Why we need culture medium?? _ we need this for study about bacteria for any medical helps. _ different types of bacteria need different types of culture media for growth. Culture media is divided into these categories: Based on consistency based on composition based on applications Based on consistency: It is of these types-- solid, semi- solid, liquid So, bacteria needs different media. And Agar is much more important for this, It is an solidifying agent. Agar [1.52 %] -- Solid Medium -- E.g. Nutrient Agar Agar [Less than 0.5%] -- Semi...
Morphological Classification of Bacteria True bacteria: 💖They are major group of classification which is further divided in to two sub-groups namely Cocci and Bacilli. 💖Cocci are various types-- >> Mono cocci (single cocci): Monococcus species. >> Diplococci (Cocci in pairs): Streptococcus pneumonia. >> Staphylococci (Cocci in a bunch form): Staphylococcus aureus. >> Streptococci (Cocci in chain form): Streptococcus pyogenes. >> Tetrad (Cocci in group in four): Micrococcus species. >> Sarcina (Cocci in group in eight, cube like): Sarcina ventriculi . 💖Thereafter, Bacilli, which are rod like structure on the basis of arrangement of organisms they are classified in to: >>Diplobacilli (Pairs) >>Streptobacilli (Chais) >>Palisades >>Coccobacilli (Oval) >>Comma shaped bacilli (Vibrio). >>Club rods (Corynebacteriaceae), >>Enlarged rods (Fusobacterium) Actinomy...
Ultra Structure of Bacteria : Under electron microscope, the structure of bacterial cell is look like a capsule. It has following components---- Capsule: 1. It is the outer layer of the bacteria cell. 2. Depending on the chemical nature capsules are thick or thin, and rigid or flexible. 3. It is most important virulence factor of bacteria which is visualized by negative staining technique. 4. Only some bacterial species possess capsule. 5. Capsule is usually made of polysaccharide (e.g. pneumococcus), occasionally polypeptide (e.g. anthrax bacilli) and hyaluronic acid (e.g. streptococcus). 6. A few capsules are polypeptides like Bacillus anthracis, is composed entirely of a polymer of glutamic acids. There are two types of capsules, 1. Macrocapsule : Thickness of 0.2 µm or more, visible under light microscope. 2. Microcapsule: Thickness is less than 0.2 µm, visible under Electron microscope. Functions: ...
INTRODUCTION TO PROKARYOTES AND EUKARYOTES:: Classification of Microorganisms: (a) Acellular organisms: These are the microorganisms that have neither cells nor cell membrane. They are composed of few genes which are protected by protein coat. Outside of the host they acts as dead but inside host they are alive and reproduce. Example: Viruses. (b) Cellular organisms: These are the microorganisms which have definite cell structures. Based on the cellular structure they are further divided into prokaryotic and eukaryotic. Prokaryotics are cells without nucleus and have no membrane bond organelles. They are less complex in structures. Examples: Bacteria and Archaeac. A. Bacteria: 1. They are prokaryotic and unicellular 2. The size is 1/1000 the volume of a typical eukaryotic cell. 3. Mainly two groups of bacteria are: (a) Archaeobacteria: Ancient bacteria. (b) Eubacteria: True bacteria. ...
Scope of Microbiology: It has impact on medicine, agriculture, food science, ecology, genetics, biochemistry, immunology and many other fields. Based on the specific groups of the microorganisms, the specialists are known as bacteriologist (Specialist in Bacteria study), virologists (specialist in virus study), mycologist (specialist in fungi study) and so on. Hence, different branches of microbiology has different role in the advancement pharmaceutical sciences where microbiologists are actively involved in research study. Some of the recent scopes are highlighted below-------- 1. Ecology and environment: Bacteria are primary decomposers as they recycle nutrients back into the environment. Winogradsky and M. Beijerinck studied soil microbes and their roles in the sulfur, carbon, nitrogen biochemical cycles. Some bacteria are used as bio-pesticides to control Insects pest. For example, Bacillus thuringiensis. Microbes ...
BRANCHES OF MICROBIOLOGY General microbiology is classified into main three branches which are tabulated below. By Taxonomy • Bacteriology: It is the study of bacteria. • Immunology: It is the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts. • Mycology: It is the study of fungi, such as yeasts and molds. • Nematology: It is the study of nematodes (roundworms). • Parasitology : It is the study of parasites. Not all parasites are microorganisms, but many are. Protozoa and bacteria can be parasitic; the study of bacterial parasites is usually categorized as part of bacteriology. • Phycology: It is the study of algae. • Protozoology: It is the study of protozoa, single-celled organisms like amoebae. • Virology: It is the study of viruses. By Type of Research ...
History of microbiology----------------------- History of microbiology is divided in to three stages namely Discovery stage , Transition stage and Modern microbiology. Discovery Stage: 1. Aristotle (384-322) described living and non-living organisms and their differentiation. 2. Roger Bacon ( 13th Century) described that diseases are caused by living creatures. 3. Thereafter in 1546, Fracastorius described that communicable diseases were caused by living agents known as germs. 4. In 1665, the first report on cell structure was described by Robert Hooke . 5. Later, during mid of 1600’s, Antony van Leeuwenhoek (1632-1723) was the first person who used a microscope of his own design to direct observations of microbes. He discovered microorganisms in 1675 and named bacteria and protozoa as “Animalcules”. He has provided full description of bacteria. From that time he was known as one of the founders of microbiology. 6. In 1659, Kircher was report...
Introduction to microbiology: Microbiology is the branch of science that deals with microorganisms. Micro organisms: Microorganisms are the small living things that include unicellular, multicellular or acellular. Unicellular are single cells organisms like cocci, bacilli, virio and spirillae. Multicellular are filaments and sheaths to form cell colonies like blue green algae (cyanobacteria), fungi, protozoans and bacteria whereas acellular are organism without cells, like viruses, prions. These microorganisms are not visible by naked eyes, only observed under microscope.