Fed-batch culture Definition In simple words, fed-batch culture is a modification to batch fermentation. In fed-batch cultivation, nutrients are added aseptically; it is a semi-open system, and the volume of liquid culture in the bioreactor increases as the culture is … Read more
Batch Culture Definition In batch fermentation, all the medium components are placed in the reactor at the start of cultivation except for atmospheric gases, acid or base for pH control, and antifoaming agents. There is a continuous change in the nutrient concentrations over time, and the system … Read more
Bioreactor Definition A bioreactor is a type of fermentation vessel that is used for the production of various chemicals and biological reactions. It is a closed container with adequate arrangement for aeration, agitation, temperature and pH control, and drain or … Read more
Introduction Fermentation is one of the ancient food processing technologies. Fermentation is defined as a process in which chemical changes occur in an organic substrate through the action of enzymes produced by microorganisms. For example, yeast enzymes convert sugars and … Read more
What is Penicillin? Alexander Fleming in September 1928 accidentally discovered Penicillin. He found that the fungus, Penicillium notatum prevented the growth of bacteria, Staphylococcus spp.. Later Clutterbuck and his colleagues in 1932 studied the nature of Penicillin and found it … Read more
Pathogenesis of Rickettsia rickettsii Human gets infected when infected adult tick inoculates Rickettsia rickettsii into the skin while taking a blood meal. It usually takes 6 hours of attachment and feeding before rickettsiae are transmitted to the host. Infection can also … Read more
Lymphocytes are the cells that specifically recognize and respond to foreign antigens and are mediators of humoral and cellular immunity. Lymphocytes, the unique cells of adaptive immunity, are the only cells in the body that express clonally distributed antigen receptors, … Read more
Macrophages The mononuclear phagocytic system consists of monocytes circulating in the blood and macrophages in the tissues. The monocyte is considered a leukocyte in transit through the blood, which becomes a macrophage when fixed in a tissue. Monocytes and macrophages … Read more
Virulence factors of Listeria monocytogenes 1. Adhesion proteins (Ami, Fbp A, flagellin) Mediate bacterial binding to host cell that contribute to virulence. 2. Listeriolysin O A hemolytic and cytotoxic toxin that allows for survival within phagocytes. 3. Internalin Cell surface protein … Read more
Definition and overview of a plant cell Plant cells are multicellular eukaryotic cells that make up a plant (a group of eukaryotes belonging to the Plantae kingdom, with the ability to synthesis their own food using water, Sunlight and CO2). … Read more
Homozygous Definition Homozygous is a genetic condition where an individual inherits the same alleles of a gene from both the parents. In homozygous chromosomes, both alleles are either dominant or recessive. The dominant trait is represented by two capital letters … Read more
Phase contrast microscopy definition Unstained living cells absorb practically no light. Poor light absorption results in extremely small differences in the intensity distribution in the image. This makes the cells barely, or not at all, visible in a brightfield microscope. … Read more
Folic acids are the enzymes that are necessary for the bacterial protein synthesis and synthesis of amino acids. Trimethoprim and Sulfonamides are the antimicrobial classes that interfere with the synthesis of folic acid at different levels and are bacteriostatic. Trimethoprim … Read more
Both light microscopes and electron microscopes use radiation (light or electron beams) to form larger and more detailed images of objects which cannot be seen clearly through an unaided eye. However, each of these microscopes has distinct features and is suitable for … Read more
Plants and animals are made up of millions of cells and these cells have several similarities and differences. Considering that they are both eukaryotic cells, which means they have a true nucleus, that is enclosed and separated from other organelles … Read more
Definition of plant cell Plant cells are eukaryotic cells, that are found in green plants, photosynthetic eukaryotes of the kingdom Plantae which means they have a membrane-bound nucleus. They have a variety of membrane-bound cell organelles that perform various specific … Read more
What is Apoptosis? Apoptosis is a normal genetically programmed cell death where an aging cell at the end of its life cycle shrinks and its remaining fragments are phagocytosed without any inflammatory reaction. The term apoptosis was first introduced in … Read more
Heterochromatin Definition Heterochromatin is a tightly packed or condensed DNA that is characterized by intense stains when stained with nuclear stains, containing transcriptionally inactive sequences. It exists in multiple variations, up to four to five state, each of which is … Read more
Fluorescence microscope definition A fluorescence microscope is an optical microscope that uses fluorescence and phosphorescence instead of, or in addition to, reflection and absorption to study properties of organic or inorganic substances. Fluorescence is the emission of light by a … Read more
Epithelial Tissue Definition Epithelial tissue is a type of animal tissue, consisting of closely aggregated polyhedral cells connected firmly to one another in the form of cellular sheets that line the interior of hollow organs and cover the body surface. … Read more
Mycolic acid is the cell wall that contains α-alkylated β-hydroxylated fatty acids present in Mycobacteria, Nocardia, and Corynebacteria. Mycolic acids are the main component of the cell wall of Mycobacterium spp and plays important role in the virulence and permeability … Read more