Online Microbiology Notes

T Cell (T Lymphocyte)- Definition, Types, Development, Applications

April 10, 2021 by Anupama Sapkota

T Cell (T Lymphocyte) Definition Thymus-derived lymphocytes or T cells are cells of the immune system that are an essential part of the adaptive immune system. These are blood cells (leukocytes) that act by attacking invading pathogens and host cells based on the type of T cell activated. T cells are different from other lymphocytes as these have a T-cell …

B cell (B lymphocyte)- Definition, Types, Development, Applications

April 9, 2021 by Anupama Sapkota

B cell (B lymphocyte) Definition B cell or B lymphocyte is a type of lymphocyte (white blood cells) involved in the humoral immunity of the adaptive immune system as they differentiate into plasma and produce antibodies. Besides, B cells are also considered professional antigen-presenting cells as these can detect antigens present on the surface of bacteria and viruses. Like in …

Microbial spoilage of canned foods and its preservation (Canning)

April 5, 2021 by Sanjogta Thapa Magar

Classification of the food based on pH The microbial spoilage of food depends upon the pH of food therefore based on pH canned food can be divided as Low-acid canned food (pH > 5.2) includes meat products, milk, dairy products, and seafood. Acid canned food (pH 4.5-3.7) includes tomatoes, pears, figs, oranges, apricots, pineapples, etc. High acid canned food (pH < …

Antibody- Definition, Structure, Properties, Types, Classes, Applications

April 4, 2021 by Anupama Sapkota

Antibody Definition Antibodies, also known as immunoglobulins, are proteins produced by lymphocytes as a result of interaction with antigens. Antibodies are a part of the humoral immune of the adaptive immune system where each antibody identifies a specific antigen and protects the body against it. Antibodies are glycoproteins that bind to antigens with a high degree of specificity and affinity. B …

Antigen- Definition, Properties, Structure, Types, Examples

March 30, 2021 by Anupama Sapkota

Antigen Definition Antigens are molecules or molecular structures that are foreign to the body and generally induce an immune reaction in the form of the production of antibodies against them. In simple words, antigens can be anything that doesn’t belong to the body and are foreign. Even though antigens are usually defined by the induction of an immune response, all …

Preservation of milk and milk products from microbial spoilage

March 29, 2021March 28, 2021 by Sanjogta Thapa Magar

Milk and its products consist of numerous nutrient content, it serves as an excellent growth medium for all of the microorganisms. Thus, various preservation methods are used to eliminate the growth of spoilage-causing microorganisms and maintaining the nutritional properties of milk. Several techniques have been used to limit the growth of organisms in milk and milk products. A. Heat treatment methods …

Microbial Spoilage of Milk and Milk Products (Cream, Butter, Cheese, Yoghurt, Ice-cream)

March 24, 2021March 24, 2021 by Sanjogta Thapa Magar

Introduction Milk is known to be balanced food as well as highly nutritious food as it is rich in proteins, fats, carbohydrates, vitamins, minerals, essential amino acids, etc. Milk and its products consist of numerous nutrient content, it serves as an excellent growth medium for all of the microorganisms (i.e., bacteria, viruses, fungi, and protozoans). The microbial content of raw …

Oxidase Test- Principle, Procedure and Results

March 23, 2021March 22, 2021 by Sagar Aryal

Objective of Oxidase Test To determine the ability of the organism to produce the cytochrome oxidase enzyme. Principle of Oxidase Test The oxidase test is designed for specifically detecting the presence of the terminal enzyme system in aerobic respiration called cytochrome C oxidase or cytochrome a3. Cytochrome C oxidase is the terminal or last H2 electron acceptor in an aerobic respiratory …

Factors affecting the growth of microorganisms in food

March 16, 2021 by Sanjogta Thapa Magar

Introduction Foods of plant and animal origin play an important role in microbial growth. The ability of microorganisms to grow or multiply in such food depends on the food environment. The intrinsic, extrinsic factors, implicit factors of food, and various food processing methods respectively play a role in microbial growth. These factors determine the microbial growth in food and the …

Food Spoilage- Types of microorganisms in foods with examples

March 14, 2021 by Sanjogta Thapa Magar

What is Food Spoilage? Food spoilage is a metabolic process that causes foods to be undesirable or unacceptable for human consumption due to changes in sensory characteristics. Spoilage of food is identified by off-colors, off-odors, softening of vegetables, fruits, and slime production. Spoilage may arise from insect damage, physical damage, and indigenous enzyme activity in food or by microorganisms (bacteria, …