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Microbiology Lab Report Experiment 4 - UNIVERSITI SAINS...

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UNIVERSITI SAINS MALAYSIAPUSAT PENGAJIAN SAINS KAJIHAYATGeneral MicrobiologyCourse code: BOI 207/3Name:Yeap Qi ChenMatric No.:130255Experiment:4 - Pure Culture TechniqueDate of experiment:13 April 2017Group: 8
IntroductionA microbiological culture is a method of multiplying microbial organisms byletting them to reproduce in designed culture media under controlled laboratoryconditions. Microbial cultures are used to determine the type of organism, itsabundance in the sample being tested, or both. Microbiological cultures arefundamental diagnostic methods used extensively as a research tool in molecularbiology. It is often essential to isolate a pure culture of microorganisms.Pure culture is a laboratory culture containing a single species of organism. Apure culture is usually derived from a mixed culture (one containing many species) bytransferring a small sample into new, sterile growth medium in such a manner as todisperse the individual cells across the medium surface or by thinning the samplemanifold before inoculating the new medium. Both methods separate the individualcells so that each will form a discrete colony when they go through repeatedmultiplication. There are three methods commonly used to derive a pure culture whichare spread plate, pour plate and streak plate. These methods dilute a heavy populationof bacteria across an agar surface.Streak plate method is designed to isolate pure cultures of bacteria, orcolonies, from mixed populations by simple mechanical separation. A mixture of cellsis spread over the surface of a semi solid, agar based nutrient medium in a Petri dishby streak plate method such that fewer and fewer bacterial cells are deposited atwidely separated points on the surface of the medium and develop into colonies afterincubation. The streak method for isolating single colonies from a mixture of cells isaccomplished with a metal sterile inoculating loop. The process is called “pickingcolonies” when it is done from an agar plate with isolated colonies and is transferredto a new agar plate using a sterile loop. The inoculating loop is used to streak over anagar surface. Many organisms are deposited on the initial region of the streak whichresulting in confluent growth and thus lesser microorganisms are deposited as thesteaking progresses. The streaking process will dilute out the sample that was placedin the initial region of the agar surface. There are two common used streak patternswhich are a three sector “T streak” and a four quadrant streak methods.Pour plate method is used to count the number of microorganisms in a mixedsample, which is added to a molten agar medium prior to its solidification. Theprocess results in colonies uniformly distributed throughout the solid medium whenthe appropriate sample dilution is plated. This technique is used to perform viableplate counts, in which the total number of colony forming units within the agar and on

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Term
Spring
Professor
N/A
Tags
Bacteria, Agar plate, Petri dish, streak plate, inoculating loop, Microbiological culture

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