Physical and Chemical Agents for Microbial Growth- myassignmenthelp

Question: Discuss about thePhysical and Chemical Agents for Microbial Growth. Answer: Introduction The control of microbial growth is an essential procedure to prevent the transmission of infections and diseases caused by the microbial agents. The microbial growth control is essential as it stops the decomposition and spoilage of foods and other consumable products and also preventing the unwanted microbial contaminations. The control of the microbial growth can be achieved through the use of chemical agents and physical agents. The physical agents and processes that can be used to control the microbial growth include osmotic pressure, filtrations, use of either too high or too low temperatures, radiations or desiccation (Carpenter-Cleland, 2017). The chemical methods commonly used to control the microbial growth include use of antiseptics, disinfectants and chemotherapeutic antimicrobial chemicals. The scientists and the healthcare professionals uses specific terminologies to precisely refer to microbial control environment hence the need to be familiar with such terms in order t o fully understand and learn microbial growth control concepts (Kilbey, 2015). Some of these terms are defined and discussed below. Antibiotic refers to a microbial derivative with the ability to kill susceptible microorganisms on inhibit their growth and proliferation in specific environment (Slonczewski, Foster, Gillen, 2014). Antimicrobial agents refer to any chemical compound that can kill or inhibit the growth of the microorganisms. The agents may vary in terms of selective toxicity and they can either be natural or chemically synthesized (Kilbey, 2015). Antisepsis is the reduction in the number of microbes with potential pathogenesis on living cells while antiseptic refers to the procedure or environment free of pathogenic contaminants such as bacteria, virus or fungus (Kirchman, 2011). Disinfection refers to elimination or reduction of the pathogenic microorganism in or on a material surface so as to make it safe. Disinfection process can be achieved through the use of antiseptic which is used externally on animal tissues, disinfectant that is used on inanimate objects and not animal tissues and the sanitizer that is used on food preparation equipments (Reis, Paula, Casarotti, Penna, 2012). Decontamination is the process of treating an objective or inanimate surface to render it safe to handle while sterilization refers to the process of destroying all the living microbes such as viruses, bacteria, fungi, protozoa among others. A sterile object is one which is free of all forms of life (Santagati, Scillato, Patan, Aiello, Stefani, 2012). Chemotherapeutic antimicrobial chemicals refer to synthetic chemicals that can be used therapeutically to kill or control the growth and proliferation of the microbes. The agents with the ability to kill the microbes are termed cidal agents while those that inhibit the growth and proliferations of the microorganisms are termed static agents (Kirchman, 2011). The purpose of the experiment was to investigate how the physical and chemical agents and processes can be used to control the growth and proliferation of two specifically chosen microbes. The two microorganisms that were used in the experiment included B. Subtilis and the E.coli. The experiments to be conducted include the Kirby-Bauer test, the lethal effects of the temperature, bleach test and determination of minimum inhibitory concentration (MIC) of antibiotic drugs. Materials and Methods The Kirby-Bauer test The test procedure was developed to help in determining the microbial susceptibility to different antibiotics. Materials used included small forceps, sterile cotton swabs, Mueller-Hinton agar plates and the paper disks impregnated with antibiotics (Slonczewski, Foster, Gillen, 2014). The antibiotics used included ciprofloxacin, moxalactam, Vancomycin, Penicilin, Polymyxin B and the Colistin. Procedure 3 was followed without any alterations on the methodology (Carpenter-Cleland, 2017). The diameters of microbes (E. coli and B. Sabtilis) migration in the plate were measured for the different drugs used. The plates were exposed in similar environmental conditions. Determining the Minimum Inhibitory concentration of an Antimicrobial Drug This is a complementary Kirby-Bauer disk test. It is a test used in microbial research laboratories to determine the lowest concentration of the drug required to prevent the growth of the microbial agent. It is usually a quantitative test as opposed to Kirby-Bauer disc diffusion test which is a qualitative test. Procedure 5 in the practical manual guide will be used to conduct the experiment (Carpenter-Cleland, 2017). The lowest concentration of the drugs that inhibits the culture growth will be recorded. Bleach Tests The experiment will employ the use of commercially sold household bleaching items such as sodium hypochlorite to determine their ability to disinfect surfaces through moderate oxidizing activities (Reis, Paula, Casarotti, Penna, 2012). The bleaching agents have the ability to control the growth and proliferations of the microbes. The experiment deployed the use of nutrient ager plates, sterile cotton swab, bleach solutions and filter discs culture and 10% bleach agent. The amount of time taken to clear the culture in the plates was recorded. Procedure 6 in the practical manual guide will be used to conduct the experiment (Carpenter-Cleland, 2017). Lethal Effects of Temperature on Microbes The experiment is set to determine the thermal death time and thermal death point for the two microorganisms under study. The material required in the experimented included water baths, test-tube racks, thermometer, nutrient agar plate, inoculating loop and the 3 days culture organisms (B. Subtilis). Procedure 7 in the practical manual was employed to carry out the practical (Carpenter-Cleland, 2017). The amount of growth in the test-tubes at different temperature was recorded. Results The Kirby-Bauer test Drugs Diameter of growth ( mm) B. sabtilis E. coli Ciprofloxacin 40 45 moxalactam No clear circle No visible circle Vancomycin 30 No visible circle Polymyxin B 20 20 Colistin 12 15 Penicilin No clear circle No visible circle Determining the Minimum Inhibitory concentration (MIC) of an Antimicrobial Drug Microorganism Concentration Used B. subtilis 0.015 E. coli 8 Bleach Tests subtilis Concentration of bleaching agent Time Taken in the Bleaching Agent 10minutes 30 minutes 0% No clear margin No clear margin 10% No clear margin No clear margin 20% No clear margin 5mm 30% No clear margin 5mm 35% 8mm 7mm coli Concentration of bleaching agent Time Taken in the Bleaching Agent 10minutes 30 minutes 0% 0.4cm 0.5cm 10% 0.7cm 1.3cm 20% 1.5cm 1.3cm 30% 2.0cm 1.6cm 35% 1.8cm 1.7cm Lethal Effects of Temperature on Microbes Temperature in 0C 40 60 80 100 E. coli Growth +++ ++ - - B. subtilis +++ +++ +++ + Discussion Disks susceptibility has been shown to be the best tool to measure the effectiveness of the antimicrobial agents against the pathogenic microbes. The sensitivity of the microbes to the antimicrobial is determined by the extent of inhibition zone in the disk plate. The larger the diameter the more susceptible the organisms to the antimicrobial hence the drug can be deemed effective for controlling the growth and proliferation of the microbes (Gould, 2016). B. Sabtilis were reported to be susceptible to ciprofloxacin, vancomycin, polymyxin B and slightly susceptible to colistin. The organisms are insusceptible to moxalactam and penicillin. E. coli species on the other hand are insusceptible to moxalactam, vancomycin and penicillin and sensitive to ciprofloxacin, polymyxin B and the colistin (Kerry, 2013). The experiment requires that all organisms exposed to similar environmental conditions such as pH and temperature. The results can be used to classify the pathogens as susceptible, re sistant or intermediate. For example both E. coli and subtilis can be termed resistant to moxalactam and penicilins, intermediate to polymyxin B and colistin and susceptible to ciprofloxacin (Greenwood, Slack, Irving, 2012). The minimum inhibitory concentration (MIC) test is quantitative tests which seek to determine the amount of the antimicrobials that can be used to control the growth and proliferations of the microbes. The study has indicated that B. Subtilis require the lowest concentration of antimicrobial to inhibit growth as compared to E. coli. As such, B. Subtilis are more susceptible as compared to E. coli. The knowledge of minimum inhibitory concentration can be used to determine the antimicrobial dosage regimen and predict the toxicity (Greenwood, Slack, Irving, 2012). The bleaching agents act as disinfect of the surfaces through reduction process hence depriving the microbe oxygen and air for respiration. The agents are used to target aerobic microbes which cannot survive in absence of oxygen. The degree of growth inhibition is greatly determined by the concentration of the bleaching agent and amount of time allowed for the reduction process (Hauschild, 2015). The higher the concentration of the bleaching agent, the higher the potential of inhibiting microbial growth as indicated in table 3 and table 4. E. coli species has been shown to be more susceptible to bleaching agent as compared to B. Subtilis species. B. subtilis is only susceptible to bleaching agent used when exposed for long time and at higher concentrations. On the other hand, E. coli is susceptible to the bleaching agent at both low concentrations and almost immediately it is exposed (Florence, 2014). The low temperature and extremely high temperatures affects the activities of the microbial hence it can be used to control the growth and proliferations of the microorganisms. Low temperatures inactivate the microbes hence inability to infect, spoil or degrade substances while the high temperature denatures the enzymes in microbes hence inactivating them (Hauschild, 2015). Therefore the growth of bacteria can be controlled by regulating the temperatures. The practical results shown in table 6 have shown that the growth of B. subtilis can occure up to 100 degrees Celsius however, its growth at 100 degrees Celsius is dramatically slowed. E. coli species can only grow up to 60 degrees Celsius hence its growth can be minimized by increasing the temperatures beyond 60 degrees Celsius (Clifford, 2015). References Carpenter-Cleland,C. (2017). BIOL 2P98 Principles of Microbiology 2017FW Lab Manual. St. Catharines: Brock University. Clifford,D. (2015). Biocides A Reasonable Alternative to Prevent and Control Microorganisms? Frontiers in Antimicrobial Agents, 12(9), 208-233. doi:10.2174/9781681081403115010011 Florence,K. (2014). Microbes and pathogens. 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