STERILIZATION TECHNIQUES
Sterilization is a term referring to any process that kills all forms of life including transmissible agents like fungi, bacteria, viruses and spore forms etc present on surface, in fluid or in medication.
Sterilization can be carried out by
v Physical method
v Chemical method
PHYSICAL METHOD:
There are some physical agents used to sterilize the objects. Some of them are
1. HEAT
Microorganisms are sometimes destroyed by constant heat. Heat is use for sterilization. The basic theme behind applying heat is to destroy the vegetative cell and eukaryotic spore but bacterial spore cannot be destroyed by heating. Heat can be used in two ways
v MOIST HEAT
Moist heat is the method in which above 100°C is applied having the aim to destroy bacterial endospore.
AUTOCLAVE It is somewhat like a modified pressure cooker. At 121°C and 15 pounds pressure for about a duration of about 15 minutes. Saturated steam is provided to destroy all vegetative cell of the microbial population. Endospores are also destroyed by autoclave. Killing is done by venturing the structure of enzymes and proteins.
The duration of treatment varies with the size of container of the liquid. The larger the size of container the more is the duration.
v DRY HEAT
Dry heat is mainly done in oven in absence of water. The items having microbes are place in an oven at 160-190 °C. The duration may vary. Often 2-3 hours of heating is done. The oxidation of cell constituent cause the death of microbes. Protein denaturation may also cause death.
Dry heat has less efficiency than moist heat.
2. FILTRATION
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...ria and fungi. It also kill bacterial spore.
3. HALOGENS
Among halogens Iodine and chlorine are important antimicrobial agent.
Ø IODINE
Iodine are effectively reduced by serum, body fluid, sodium thiosulphate and feces. Iodine acts more rapidly than other halogens. Iodine is use as skin antiseptic.
Ø CHLORINE
Chlorine is having good germicidal activity. Its solution makes very effective laboratory and house hold disinfectants.
4. ALDEHYDES
Aldehydes such as formaldehyde and glutaraldehyde have wide microbial activity. They are sporocidal and fungicides.
Ø Formaldehyde is water soluble gas. It is germicidal for bacteria, fungi and viruses. At its higher concentration spores are killed as well. It is use to disinfect surface.
Ø Glutaroaldehyde is also used for disinfection purpose.
Steam sterilisation is the process where “dry saturated steam comes into contact with a cooler surface, that causes water condensation and immediate release of the latent heat” (Rohanizadeh, 2016). This process was carried out in an autoclave and is the preferred method of sterilisation as the ampoules are sealed and made from glass. Being sealed causes a high amount of pressure to build up inside the ampoule, though in an autoclave they will not burst due to the high pressure in the autoclave equalizing and compensating for the high pressure in the ampoule. If a dry heat method of sterilisation was used, e.g. an oven, the ampoules would burst due to evaporation of the solution occurring, and no compensation or equalised pressure availability, like we see in the autoclave.
The Citrate medium, a.k.a. Simmons Citrate Agar, contains sodium citrate as the sole carbon source and ammonium phosphate as the sole nitrogen source (Stout et al, 43). To perform the Citrate test, I used the stabbing technique to inoculate the Citrate media. I sterilized the stabbing utensil under an open flame, obtained a small amount of unknown bacteria, and stabbed the Citrate media. Once the Citrate media was inoculated, I let it incubate for 24 hours in the 37°C hot room. After the 24-hour incubation, I reviewed the Citrate media for a change in the PH of the media, which was indicated by a color change of blue or green.
After the incubation period, the tube will be centrifuge using table top centrifuge machine for 10 minutes at 2500 rpm. Centrifuging process should causing the bacteria and other cell debris to form a pellet at the bottom of the tube. The supernatant produce will be taken up about 3 mL using a syringe. A 0.22 micron filter will be attach to the base of the syringe and the supernatant will be filter into a sterile tube. Any remaining bacteria are prevented from passing through the filter except for phage. The filtrate will be label as ‘Enrich Phage’ and store it in refrigerator. By the way, one more overnight culture of Salmonella will be set up.
Transformation of bacteria can happen by two different procedures, electro-puration, or electro-compentent. Electro-puration was the method used, it involves heat shocking the cells with calcium ions. This was the method used because it left the most amount of viable cells as compared to other methods.
First, hand sanitizer is made up of key ingredients. There is an active ingredient, which is the ingredient that kills the germs. This is usually alcohol, but can be many other things like ethyl alcohol, isopropyl alcohol or a combination of both. “Benzalkonium chloride is another FDA-approved active ingredient in some hand sanitizers. Although it is not an alcohol, benzalkonium chloride also works to kill bacteria and some viruses on the hands” (Jackie). Also, there are humectants added. Humectants are added to hand sanitizer to moisturize the skin. Glycerin and propylene glycol are humectants. They are commonly used in hand sanitizer. From the humicants holding water, they help prevent your skin from drying with frequent use of hand sanitizer because the active ingredients can dry out your skin. There are more ways of hand sanitizer moisturizing your skin. For example, “Isopropyl myristate is an emollient, which is a chemical that seals the skin surface and makes it smoother. It is made from a substance naturally found in nutmeg, coconut oil and some animal fats. Many hand contain isopropyl myristate and moisturizers, such as aloe vera and tocopherol acetate, or synthetic vitamin E” (Jackie). Carbomer and amniomethyl propanol are common ingredients used as binding agents. Emulsifiers keep other ingredients f...
The materials that were used in this lab included a 100/1000 μL micropipetter, 4 agar plates with pre-poured LB broth , ice bath, hot water bath, micro centrifuge tubes, sterile loops, UV light, as well as pGLO plasmids and E.coli.
The scientific techniques that were mainly used in the conduction of our investigation were the identification of bacteria through the use of a microscope, putting together a Simple Distillation Kit, treating Petri Dishes with Agar on them with the boiled, distilled or radiated water and calculating the coverage of bacteria on the amount of area treated on the Petri Dish. All of these scientific techniques were a crucial part of our investigation. Without all of these techniques we wouldn’t have been able to conduct such a successful experiment.
This method is usually carried out on ready to eat food and processed meat and poultry. This method is a proven way to extend shelf life by killing microorganisms and pathogens, which are the reason processed meat such as deli meats last so long. However, there are negative effects of this method. There is a change in nutritional value and sensory value in foods that have been used in this process. It can change the flavour and can cause vitamin and protein destruction. However, non-thermal methods offer an extension in shelf life without changing the sensory values or nutritional values. It is a low cost method of food processing also. Non thermal methods have a big place in the future of food processing as consumers are becoming more aware of the nutritional value of the food, as well as wanting to save money and enjoy the flavour of the
A self-sterilizing formula is one that either prevents microbial growth (bacteriostatic) or kills-microorganisms (bactericidal /microbicidal).a self –preserving formula may or may not contain antimicrobial preservatives. Relatively anhydrous products (e.g. talcum powder, corn starch, mineral oil, and stick deodorants) do not require preservatives because they do not have sufficient water content to supply microbial growth. However, manufactures may incorporate preservatives in to these products to prevent microbial growth that may occur due to addition of water by consumer during use or abuse. The physicochemical make-up of the product, including low water activity (aw), high or low pH, and multifunctional materials that have antimicrobial properties (e.g. alcohol, surfactants, quaternary ammonium companies) determines whether a formula is self-preserving. Aqueous products in multiuse containers generally require the addition of preservation if they do not prevent microbial growth. The type of packaging and consumer use habits determines the preservation requirements of a
In the Transformation lab, we saw how protein glowed in bacteria. First we scooped out bacteria from a petri dish and added it into positive and negative labeled test tubes. We then pipetted calcium chloride into the test tubes. The calcium chloride adds positive charges into the mix. The test tubes are then placed into an ice bath to cool the bacteria down before they were removed and put into hot water. This process kills some of the bacteria creating an apocalyptic environment. Those that did not die took in an extra plasmid in an attempt to survive. The plasmid helped them survive the heat. Not all bacteria took in plasmid. The tubes are then placed back into ice to calm the bacteria. The bacteria was then pipetted out of the test tubes
The chemicals used in the embalming process will cause many health and environmental problems for those who handle the solvents. Formaldehyde, glycerin, borax, phenol, alcohol, and water are the typical ingredients of embalming fluid (Mitford, 2005). Many of these chemicals are corrosive and are carcinogens that absorb into the skin of the...
The petri dish was inoculated with a cough and placed in an incubator for 120 hours at 98.6 degrees Fahrenheit. The results from petri dish two revealed minimal growth of bacterial spores. This exercise revealed the desired results.
With sterilization being forced upon them, the patients would not expect this to happen and have a heavy, emotional response to it. Many sources show that patients that commonly experienced compulsory sterilization were women and those in prison or in a mental institution. For example, within the 1970s, patient Julie was sterilized without being informed, though signed a form for it, believing it to be for a painkiller, and her husband left her upon finding out about her sterilization because he “wanted a real woman” (Peal). As far as sterilization in prison goes, it has been both forced and informed, depending on how the situation has gone. In 1909, Californian “medical superintendents of asylums and prisons” could sterilize their patient, so long as it actually improves the person physically, mentally, or morally, though this sterilization law has changed over the years (Stern 1129). On December 18, 2006, Tessa Savicki went to Baystate Medical Center for a Caesarean section, only to later find out that the surgeons had tied her fallopian tubes after delivering her baby (Diaz-Duran). Savicki expresses her emotions as shocked, upset, and disgusted by the action that caused her to be sterile permanently, fearing that her husband would leave her because of that (Diaz-Duran). In the case of 2007, Crystal Nguyen of Valley State Prison for Women worked in the prison’s medical center and overheard the staff asking inmates, like herself, to be sterilized. Christina Cordero was an inmate for two years who agreed to be sterilized, pressured by a medical staff member into feeling like “a bad mother” of five, but as of 2008 she quotes, “Today I wish I would have never had it done.” (Johnson). These patients exhibit disapproval to this compulsory sterilization, even when agreeing or almost tricked into
These are just some of the substitutes for harmful chemicals in the house. At least when you clean you house you don’t have to worry about hurting your child or yourself if you use the alternatives.
Thermal death point (TDP) is the temperature at which a culture of organism is killed within a short...