Microbial growth cultivation of microorganisms

• Microbial growth refers to an increase in cell number, not in cell size.
• Increase in cell number can be achieved through reproduction, which is always asexual in prokaryotes.
• Microbial growth involves the formation of new cells through replication of DNA and partitioning of cellular components into two daughter cells.
• Binary fission is the most common mechanism of cell replication in bacteria.
• Binary fission in bacteria starts with the replication of DNA as the cell elongates.
• A division septum forms in the center of the cell during binary fission.
• Two daughter cells of similar size form and separate during binary fission.
• Each of the daughter cells receives a copy of the original chromosome during binary fission.
• The reaction of SOD involves the use of Oxygen (O2) and results in the formation of water (H2O) and a molecule called Superoxide (O2-).
• Catalase is an enzyme that breaks hydrogen peroxide into water and O2.
• SOD is made by aerobes, facultative anaerobes, and aerotolerant anaerobes, but not by anaerobes or microaerophiles.
• There are two different enzymes that break down hydrogen peroxide: Catalase and Hydrogen Peroxidase.
• Hydrogen Peroxide (H2O2) is a toxic substance and the active ingredient of several antimicrobials such as benzoyl peroxide.
• Fragmentation is a form of asexual reproduction where an organism splits into fragments, each of these fragments develop into mature, fully grown individuals that are clones of the original organism.
• Fragmentation is commonly observed in Actinomycetes, a group of gram-positive, anaerobic bacteria commonly found in soil.
• Budding is a form of asexual reproduction in which a new individual develops from some generative anatomical point of the parent organism.
• Budding is most common in yeast.
• Lyophilization (freeze-drying): Frozen (-54° to -72°C) and dehydrated in a vacuum.
• In eukaryotic organisms, the generation time is the time between the same points of the life cycle in two successive generations.
• The typical generation time for the human population is 25 years.
• This definition of generation time is not practical for bacteria, which may reproduce rapidly or remain dormant for thousands of years.
• In prokaryotes, the generation time (the doubling time) is defined as the time it takes for the population to double through one round of binary fission.
• Bacterial doubling times vary enormously, with Escherichia coli able to double in as little as 20 minutes and Mycobacterium tuberculosis, the causative agent of tuberculosis, having a generation time of between 15 and 20 hours.
• Selective media favor the growth of some microorganisms and inhibit growth of others.
• Fungi can tolerate drier environments.
• Blood agar is a functional type that supports the growth of many fastidious bacteria and bacteria can be differentiated based on their ability to produce hemolysis.
• Solid media contain a high percent (1-5%) of agar, enabling the formation of discrete colonies.
• Culture media are required to grow, transport, and store microorganisms in the laboratory and must contain all the nutrients required by the organism for growth.
• Differential media distinguish between different groups of microorganisms based on their biological characteristics.
• Smooth colonies are S type, rough colonies are R type, and mucoid colonies are M type.
• Requirements for bacterial growth include nutrients, water, carbon source, nitrogen source, inorganic salts, growth factors, pH, temperature, and gas culture medium incubator.
• In microbiology, culturing is essential for growth and maintenance of microorganisms, isolation and identification, testing for antibiotic sensitivity, water and food analysis, and industrial microbiology.
• Chocolate Agar is a functional type that is enriched and has the same composition as Blood Agar, but the red blood cells are lysed during preparation.
• Microorganisms depend on available water to grow.
• Water and water activity are crucial in cultivation of microorganisms.
• Liquid media are water-based solutions without agar and are generally termed broths, milks and infusions.
• Observing microorganisms’ colonial morphology, and growth characteristics on solid media helps us to obtain pure cultures.
• Decreasing the water content of foods by drying is a common method of preventing food spoilage.
• Peroxidase converts hydrogen peroxide into water.
• Nutritional requirements of a bacterium such as E. coli are revealed by the cell's elemental composition, which consists of C, H, O, N, S, P, K, Mg, Fe, Ca, Mn, and traces of Zn, Co, Cu, and Mo.