![]() ![]() In this course, all media, the substance in which the cells are grown, is sterilized by autoclave.Preventing Infections with Aseptic TechniqueĪseptic technique is a requirement for all invasive procedures, with the central goal for clinicians to maintain asepsis in the healthcare setting through hand hygiene, non-touch technique, glove usage and the sterility of equipment. ![]() Sterilization is all or none something is either sterile or it is not sterile. ![]() Sterilization is the complete removal all vegetative cells, endospores, and viruses from an item (OpenStax CNX, 2018). The term “aseptic” literally means “without contamination.” These procedures are as important for the experimenter’s safety as they are for maintaining culture purity. Aseptic technique is the collection of procedures and techniques designed to prevent the introduction of unwanted organisms into a pure culture or into the laboratory environment. If an unintended microorganism is introduced into a pure culture, the culture becomes contaminated. Microbiologists generally study the organisms in pure culture, a culture that contains a single microbial species. In addition, specialized media in plate form is used for certain biochemical tests. In a few weeks, you will be using a series of plate cultures to separate two different microbes from a mixture. Bacterial cells can be spread out over the surface so that they form discrete colonies which can be characterized. In contrast to deeps and slants, agar plates have a large surface area for growth. Deeps are often used to for certain differential metabolic tests. These types of cultures are called stocks. (Petersen, 2016)įigure 1: Illustration showing the different forms microbiological media can be prepared as.īecause of the relatively small tube opening (less opportunity to dry out or become contaminated) and the surface area available for growth, agar slants are commonly used to culture and store bacteria for intermediate periods of time (weeks). Agar plates are made by pouring melted agar into a petri dish. Melted agar is poured into a test tube and then allowed to solidify vertically for an agar deep, or at an angle for an agar slant. Making solid media is similar to making Jell-O, where a powder is mixed into water and heated to fully dissolve the powder. Solid growth media is used in the following forms: agar plates, agar slants and agar deeps. It is used as a solidification agent because it (1) is not broken down by bacteria, (2) contains no nutrients that can be used by bacteria and (3) melts at high temperatures, and yet is solid at temperatures used for most bacterial growth. Solid growth media usually contains agar, which is a mixture of polysaccharides derived from red algae. They are also the method of choice for growing large quantities of bacteria. Broths can be used to determine growth patterns in a liquid medium, and for certain types of inoculations and metabolic tests. Growth media can be either liquid or solid.Ī liquid medium is called a broth. Microbes are grown in substances that provide the nutrients necessary to sustain their metabolic activities and reproduction called "growth media" or simply "media" (singular is "medium"). To study bacteria and other microorganisms, it is necessary to grow them in controlled conditions. ![]()
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