Microbiology: Common Aseptic Transfer and Inoculation Methods PDF

Here is the converted text from the images you sent: # EXERCISE 3 ## Common Aseptic Transfer and Inoculation Methods After doing this exercise, you should be able to: 1. Identify the various formats of growth media and properly inoculate them. 2. State the goals of aseptic methods. 3. Correctly...

Here is the converted text from the images you sent: # EXERCISE 3 ## Common Aseptic Transfer and Inoculation Methods After doing this exercise, you should be able to: 1. Identify the various formats of growth media and properly inoculate them. 2. State the goals of aseptic methods. 3. Correctly apply aseptic methods while handling bacterial cultures and media. 4. Describe the necessary aspects of aseptic culture transfer. ## Background Growing bacteria is a basic procedure in any microbiology lab. Into a growth media, a liquid, solid, or semisolid substance that provides necessary nutrients for specimen growth. Growth media (or simply, media) come in hundreds of. The teCi@ uæd dcpCØÒ oğ ùe goäĘ äom. $**m li**d $røwth æ bacterial sp«iæ diffeientiæêon anÕ or isoŁéoi» Hem I'll tevleæ æmc basicœ about gtowa media and Õe aøeptic methods Õc Ôocubting such mediæ. Methods used for species isokåœ (e.gø Õe streak plne isokãon) and Õe coßection of media uæd for diflerentinting bacterial specicæ äom one anoÕei. In general, grøwtb media have Útber a deäned'or a) pth&æme %m &bc MteAA organic and Òorganic ingredient a precisely known æid 5. Compare complex media to defined media and provide examples of each. 6. Define the terms mixed culture and pure culture. 7. Describe ways to minimize risks when working with BSL-2 agents. 8. Properly label microbial samples. Bacterial growth applications beelm it reinni aolid R standard Ocubaãon mnpernturæ and mum ţmtbfUm can't digest it. The thickened media can be poured into sterile petri plates to make agar plates, upright test tubes to make agar deeps, or tilted test tubes to make agar alønu (Fiç 3.1). Plated media are used for isolating species, differential testing, and quantifying bacterial levels. We won't use plated media in this lab exercise, but we'll use them later. Agar slants are used for a variety of biochemical tests and, useful br mainteáikg stock cuſturæ Moa deeţø am tĞd to determine specific bacterial metabolic properties. No matter what media we use, each requires aseptic quantified, which means these media are accurately reproducible. Glucose minimal salts media is an example. In contrast, complex media (also called enriched media) contain ingredients such as milk proteins, blood, or yeast extracts, less precisely defined organic nutrients. Most pathogens are fastidious (require complex nutrient sources) and will only grow on enriched media. In this lab exercise, we'll use a complex media called nutrient broth, which contains peptone (a solution of partially broken-down proteins) and beef extract. Two Important Media Formats: Liquid and Solid As their name suggests, broth media are liquids. Liquid media are great for quickly growing large quantities of bacteria. This is because high-volume batches can be readily prepared and easily inoculated. However, sometimes a solid media format is required. To make solid media, we simply add agar to liquid media. Agar is purified from seaweed. It has the same solidifying effect as gelatin, but it's better for most. Figure 3.1 shows different media formats as follows: * Plate * Deep * Slant * Broth when growing bectxia » the lab, wc s\_jggLgj1ÎLa, sample containing bacteria. If due sa ple. pnlq priC sacs-i•w, wc call it a e, a contiins mo than No matter what type of culture wc start when transferring it to new media we must avoid aNiôonal. cavkxænænt and we zoô avoiô exposing ourselve and pur surroundings to tlie microbes in. 'Yo achieve this, we uæ ascetîc meth£;;Jc (d WItÙO septi¿ = contaminationj, which involve and sterile inoculating tools. One goal of aseptic methods is to avoid contaminating with using sterile media. growih gàxlin tguæ bgzterüe befàre ir's inoculaæd. There ue. Approach is to use an *autoclave*, a chamber that steam heats a sample under pressure. anything that will directly contact the AyA"alao bc ex1€e. 3Aia Tociuclcs tbc ſatcriar of &c., hold tbc moäa. There are the media can be mix&d and poured into the tubes and then immediately autoclaved so the media twaroenare émokanosuslerilized, or. potential pathogens. You must do two things to accomplish this. First limit how much vn\_j jour SaFFtple to the «ovironment. Aerosols and AO delve into each process as we walk through the inoculation procedures. Here is a list of things to keep in mind: * Pay attention to your environment. Your workspace should be clutter free. Never perform transfers over your books aRd papers because you may unknowingly contaminate them. * Thoroughly label all media. Arrange all media in advance and clearly label them with your name, the date, the type of medium (e.g., nutrient broth, or NB for short), and Ae bacterium'sname (or the sample name, such as Unknown \#3). Never la&1 lids. Innead, label the body of your tubes with tape, paper held on with a rub&r band, or by writing directly on the glass. For plastic plates, write direcly on the base (not the lid). Your instructor will tell you their labeling preferences. Whatever labeling method used, & sure you position labels so they don't obxure your view of the media. * Keep test tubm in a test-tube mck. Never fay tubes on the able; they may leak or roll oK. * Take your ôme. You are handling potentially dangerous micro&s. &forking at a frenzied pace leads to accidents. Sterile Inoculating Tools All inoculating tools used to transfer the sample to the sterile media must also be sterile. There are many inoculating tools available, but in this lab exercise, we'll use a wire inoculating needle and a wire inoculating loop to pick up small amounts of a culture and transfer it to our media. An inoculating loop has a handle that holds a thin tungsten, platinum, or nichrome wire twisted into a small loop at the end. An inoculating needle is basically the same as a loop, except the wire is straight. To sterilize the loop or needle, the tool's wire filament is inserted into an incinerator or Bunsen burner flame until the filament glows red-hot. If presterilized disposable inoculating loops or needles are used, then the incineration/flame sterilization process is skipped. Sometimes other inoculating tools like pipettes are used; these are covered in Appendices C and D. Protecting Yourself and Others When properly performed, aseptic methods help you avoid sample contamination, but more importantly these techniques protect you and others from exposure to. Figure 3.2 Wire Inoculating Needle and Loop. The figure is of two needles; one with a loop.