Sec 5: Microorganisms Growth

MICROORGANISMS GROWTH Growth and Replication of Microorganisms Microorganisms or often called microbes live freely in the environment, spreading in the air, oil, water, food, there are even microbes that live in the human body. Microbes can survive in the environment by carrying out the process of microbial growth. Microbial growth can be defined as the regular increase of all chemical elements in microbial cells. Growth Microbes involve increasing size and increasing number.The balance between these two processes, the end result is an increase in total mass (biomass). Bacterial growth can be defined as the regular increase of all chemical components of the cell. Cell multiplication is a consequence of growth that leads to an increase in the number of bacteria that form a population or culture. Most bacteria divide by binary fission where the bacteria undergo cell division to produce two daughter cells that are identical to the parent cell. Bacterial growth can be compared to the number of cells: one bacterium divides into two, both of which produce four, then eight, and so on. Under the right conditions (nutrition, correct temperature, etc.) microbes can grow very quickly. Depending on the situation, this can be a good thing for humans (e.g. growing yeast suitable for making beer) or a bad thing (bacteria growing in the throat causing laryngitis).It is very important to have knowledge about microbial growth, so that you can predict or control microbial growth under certain conditions. While the growth of multicellular organisms is usually measured in terms of an increase in the size of a single organism, microbial growth is measured in terms of an increase in population, either by measuring an increase in the number of cells or an increase It is possible to predict the number of cells in a population when they divide by binary fission at a constant rate. For example, Consider what happens if one cell divides every 30 minutes for 24 hours. Bacteria undergo fission, namely binary fission in which individual cells enlarge and divide to produce two offspring of almost the same size. Nuclear division precedes cell division. Therefore, in a continuously increasing population, many cells carrying two nuclear bodies can be seen. Cell division occurs by a constrictive process or by the growth of a transverse septum across the cell. Daughter cells may remain partially attached after division in some species. Alternative Patterns of Cell Division Binary fission is the most common cell division pattern in prokaryotes, but it is not the only one. Other mechanisms usually involve asymmetric division (as in budding) or the production of spores in aerial filaments.In some cyanobacteria, many nucleoids can accumulate in enlarged round cells or along filaments, which leading to the generation of many new cells at once. New cells often split from the parent filament and drift away in a process called fragmentation. Fragmentation is commonly observed in Actinomycetes, a group of grampositive anaerobic bacteria commonly found in soil. Another strange example of cell division in prokaryotes, reminiscent of live birth in animals, is exhibited by the giant bacterium Epulopiscium. Some daughter cells grow completely on the parent cell, which eventually disintegrates, releasing new cells into the environment. Other species can form long narrow extensions The tip of the extension swells and forms a smaller cell, a bud that eventually detaches from the parent cell. Budding is most common in yeast, but is also observed in prosthecate bacteria and some cyanobacteria. Actinomyces soil bacteria grow in long filaments divided by septa, similar to the mycelium seen in fungi, producing long cells with many nucleoids. Environmental signals, possibly related to low nutrient availability, lead to the formation of aerial filaments. Within these air filaments, elongated cells divide simultaneously.The new cells, containing a single nucleoid, develop into spores that give rise to new colonies.