JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy II PHARMACEUTICAL MICROBIOLOGY Previous Question Paper (September-2021 - R17)
Answer any five questions. All questions carry equal marks.
Main
Mention the various ingredients used in bacterial cell culture media and describe their significance.
Answer
Bacterial culture media are complex mixtures of nutrients designed to support the growth, survival, and reproduction of microorganisms. The essential ingredients and their significance are as follows:
- Water: Serves as the universal solvent and the medium for all biochemical reactions. It is essential for the transport of nutrients into the cell and the removal of metabolic waste products.
- Carbon Sources: Carbohydrates like glucose, lactose, or sucrose provide the necessary energy and carbon skeletons for synthesizing cellular components.
- Nitrogen Sources: Peptone, tryptone, beef extract, or yeast extract provide amino acids and nitrogenous bases required for the synthesis of proteins, enzymes, and nucleic acids.
- Mineral Salts: Inorganic salts such as phosphates, sulfates, and chlorides of sodium, potassium, magnesium, and calcium are essential for maintaining osmotic pressure, acting as enzyme cofactors, and stabilizing cellular structures.
- Growth Factors: Vitamins, amino acids, and purines/pyrimidines are added for fastidious organisms that cannot synthesize these essential compounds themselves.
- Solidifying Agents: Agar, derived from red algae, is the most common agent used to solidify liquid media. It remains solid at incubation temperatures and is not degraded by most bacteria.
- Buffers: Compounds like phosphates are added to maintain a stable pH, preventing the accumulation of acidic or basic metabolic byproducts that could inhibit bacterial growth.
- Selective and Differential Agents: Dyes (e.g., crystal violet), antibiotics, or specific indicators (e.g., phenol red) are included to inhibit the growth of unwanted organisms or to distinguish between different species based on their metabolic activities.
The precise combination of these ingredients depends on the specific nutritional requirements of the target microorganism, ensuring optimal growth conditions in the laboratory.
Bacterial growth cycle
Answer
The bacterial growth cycle describes the pattern of population growth in a closed system, typically occurring in four distinct phases:
- Lag Phase: A period of metabolic activity where bacteria adapt to the new environment. There is no significant increase in cell number, but cells are synthesizing enzymes, RNA, and proteins required for division.
- Log (Exponential) Phase: Cells divide at a constant, maximum rate through binary fission. The population doubles at regular intervals, and the metabolic rate is highest. This phase is most sensitive to antibiotics and adverse environmental conditions.
- Stationary Phase: The growth rate slows and eventually equals the death rate due to the depletion of essential nutrients and the accumulation of toxic metabolic waste products. The total population remains constant.
- Death (Decline) Phase: The number of viable cells decreases exponentially as conditions become unsuitable for survival, often due to extreme nutrient exhaustion and toxic buildup.
Isolation and preservation of pure cultures.
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Describe the physical and chemical methods of sterilization.
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Describe the equipment’s employed in large scale sterilization and write a note on sterility indicators.
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Describe the factors influencing the actions of antiseptics and disinfectants? Write a note on bacteriostatic agents.
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Describe the pharmacopeial methods available for the sterility testing of solid and liquid pharmaceuticals.
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Describe the methods available for the standardization of antibiotics and vitamins.
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Describe the general procedures involved in animal cell culture? Mention the pharmaceutical applications of cell culture.
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