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Control of Microbial Growth Lab
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Microbial growth refers to the notion of the quantity of cells in an organism, not to the variations in the scope of cells. Colonies are the buildups of cells large enough to be visible without a magnifier. It implies that all chemical components of the cell increase with the same speed and after a definite time this leads to the upsurge in cell number, which subsequently causes the increase in the size or number of the individual cells, which generally performed batch-wise or continuously in cells. The bacterial requirements for growth comprise such sources of energy as organic carbon molecules and metal ions.
The Importance of Controlling Microbial Growth
Microbial growth control is of relative importance in many practical situations that are significant in the advancement of food science, medicine and agricultural industry. It is used mainly to prevent the growth and inhibit of microorganisms from further advancing by killing them using chemical or physical agents known as cidal agents. Microbial growth control is vital in pharmaceutical and biotechnological industries, including academic research and the medical fields, like surgery. These physical and chemical agents play a role in suppressing and eliminating microbial and bacteria life of microorganisms that affect an organism preventing further health hazards. The reasons for controlling microbial growth include the prevention of decomposition and spoilage in the bacterial growth, prevention of disease transmission and infection and prevention of contamination, like the communicable of diseases or organisms through contact or dispersal.
The Methods and Mechanisms Used in Controlling Microbial Growth
There are two key methods and mechanisms used in microbial growth control, which include the use of physical and chemical agents. It is necessary to maintain a balance between microbes and living organism like humans through the results of control that include the stasality and cidality of the microorganisms. These methods of controlling microbial growth kill and eliminate all possible forms of microbial existence that are present in solutions, on the surface or on concrete compounds that have health risks to the environment.
The Physical Methods of Microbial Growth Control
The physical methods for controlling and monitoring the growth of microorganisms are divided into heat methods and non-heat methods. Heat methods include dry and moisture heat that eradicates microorganisms by reacting with the microbes and oxidizing their proteins to kill them. Dry heat is used in burning devices, which include hot-air oven or Bunsen burner that produces high temperatures. In the presence of extreme higher temperatures, microbes are rapidly killed and destroyed. Boiling water, for instance, releases moist heat that is used to kill microorganisms present in vegetables or other organisms. Drying of the microbes using heat is usually used to control the growth of microorganisms in the essence that when water is removed from the cells they shrivel and die eliminating their existence. It is also important to use the other numerous non-heat methods like filtration, electron beam and gamma radiation, which are also available to control the presence and prevent the growth of the microorganisms.
Filtration is a commonly used practice in which gas or liquid is passed through a series of small pores that retain the microorganisms and prevent them from growth due to the high volatility of the gasses and liquid. Irradiation is another method of non-heat growth control that usually distorts and destroys all nucleic acids present in microbes. Ultraviolet light is frequently used in microbial growth control to sterilize objects and the surfaces of things like those in research labs. Gamma radiation, x-rays and electron beam radiation are also widely used in controlling the growth of microbes by ionizing, that is breaking down molecular and chemical bonds with electrons of atomic constituents that are produced in the radioactivity, which kills the microorganisms. The refrigerator uses cold temperatures that are below freezing points to control the microbial growth of bacteria. Microbial metabolism slows down at low temperatures considerably reducing the reproductive rate of the microbes. It is, however, known that cold temperatures do not undoubtedly kill all microorganisms present but at freezing temperatures, many microbes are killed due to the ice crystals present.
The Chemical Methods of Microbial Growth Control
Chemicals are used majorly for the sterilization of objects, which include liquids like glutaraldehyde and gases such as formaldehyde and ethylene oxide. Hydrogen peroxide, Ozone and peracetic acid are also other examples of chemical sterilization methods based on oxidative proficiencies of the chemical used to kill the microbes in microorganisms. Ethylene oxide (ETO) is frequently used as another form of chemical sterilization in microorganisms due to its low temperatures of the boiling point of about 10.4º Celsius at atmospheric pressure. Its gas at room temperatures is highly useful in killing the bacteria present on the surface of objects. Another chemical agent is a phenolic agent, which damages the cell membranes of microorganisms and inactivates the existing enzymes while denaturing their proteins from the microbes. Cresols such as Lysol are phenolic agents, as well as bisphenols like hexachlorophene that are particularly active against staphylococci. Chlorine and iodine are the other chemical agents acting as halogen antiseptics and disinfectants used to control the microbial growth. Microbial proteins combine with iodine, which inhibits their vital function of eliminating microbes from organisms.
The Resistance of Microbes to Different Methods of Microbial Growth Control
Endospores are reflected to be the most resistant edifice of microbes. They are resilient to most chemical and physical agents that would typically kill the vegetative cells that are formed from. Mycobacterial contamination is also another notorious element difficult to treat with these agents while protozoa cysts are also hard to eliminate due to their structures. The resistance of microbes is also influenced by gram-negative species, which have high levels of regular antibiotic resistance to the agents. Staphylococcus aureus, as well as fungal cells are infamous to resistant of human pathogens and treatments. Some of the easiest bacteria to eliminate include yeasts cells and vegetative bacterial. Viruses, especially the encased ones, are also comparatively easy to treat using chemicals owing to the presence of lipids associated with them.
The Effects of Antiseptics and Disinfectants on the Microbial Growth
Antimicrobial agents are classified as antiseptics and disinfectants. They include alcohols, aldehydes, anilides, biguanides, diamidines, silver compounds, peroxygens, phenols, and halophenols. Various forms of microorganisms differ in their response to the antiseptics and disinfectants attributable to their different cellular composition, physiology and structure due to their unlike categories of organisms reacting contrarily.
It is important to note that resistance can be either the acquisition of transposons, natural or acquired by mutation. The nature and structure of these coatings depend on the organism type to reduce the uptake. The conflict of antiseptics and disinfectants advances during sporulation at an early, intermediate, or late occurrence. The resistance of microbes is supplementary with their composite cell walls, which provide an efficient barrier to the entry of the agents. The efficiency of antiseptics and disinfectants is tested using the disc-diffusion or filter paper disc method.
How to Set Up The Kirby-Bauer Test and Analyze the Results
Place a filter paper disc that has been soaked with commercially available antiseptics and disinfectants on the Mueller-Hinton agar plate, which has been inoculated by the bacteria mostly through the spread plate method used. Measure the zone of inhibition after the incubation for each disinfectant and antiseptic. The test is established on the concentration of the agent from the area of higher absorption to the area of lower concentration. If the bacteria is subtle to the antiseptic or disinfectant, it will fail to grow up to the edge of the disc.
It will hence create a perfect zone called the zone of inhibition around the disc of the test. Any microorganisms unaffected by the disinfectant or antiseptic will grow to the level of the disk. The zone of inhibition, that is a larger one, does not mean that the agent is more active as it inhibits the microorganism and does not mean that the agent has a bactericidal effect on the test.
The concentration rate depends on the diffusion and the molecular weight of the agent being used in the test.
Ever since the microbes were proven to cause diseases, researchers have invented different methods to control their extent. Regulatory microbial growth is important in the food industry, medical field, biotechnology industries, pharmaceutical and academic research. Each agent achieves a different level of microbial elimination by a definite contrivance. Through monitoring the microbial growth, controlling its impact is viable in enhancing better results to pharmacists and medical practitioners.

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