Streaking microbial cultures on agar plates university of missouri. There are alternative methods for preparing a streak plate but the method shown is the. This general microbiology practical lecture explains the pure culture isolation techniques like streak plate, spread plate and pour plate method. Furthermore, we can use an inoculating loop or cotton swab as an inoculating tool in streak plate while we need a spreader for spread plate technique. Streaking technique obtain pure cultures cultivation of. See the instructional photo that appears with this article. The streak plate technique is the most popular method for isolating specific bacteria from a sample containing a mixture of microorganisms. The plate count method or spread plate relies on bacteria growing a colony on a nutrient medium. Pour plate technique for the isolation of microorganism. Streak plate method principle, methods, significance, limitations. A template for the streak plate isolation technique for. Minimize the amount of agar and the length of time the agar is exposed to the environment during the streak process. Flame your loop and remove one colony from the mixed culture and streak one of the halfcircles in a continuous backnforth line. Streak plate technique for isolation of microorganism.
On the other hand, spread plate technique allows you to enumerate bacteria. Reading in order to study microorganisms and observe their characteristics it is first necessary to. In order to obtain well isolated discrete colonies, the quadrant streak technique should be used. The pour plate method of counting bacteria is more precise than the streak plate method, but, on the average, it will give a lower count. Agar streak plates are an essential tool in microbiology. Module context this module introduces microbiological laboratory techniques to be used for analysis of coliforms bacteria can be used as indicators of pollution. This uses either the three streak or four streak methods. Isolate single bacterial colonies by the streakplating method. Perform a pourplate loop dilution to separate cells of a mixed culture and compare growth characteristics beneath and on the surface of the agar. A sample is taken from a colony and a microbiological culture is grown on the new plate in order for the organism to be identified properly. Area of the second streak from the area 1 yields gives dense growth. The method most often used in the clinical laboratory is the quadrant method. Streak plate method of isolation purpose the streak plate technique is the most widely used method of obtaining isolated colonies from a mix of cultures.
Introduction to streaking and culture maintenance the immediate objective of the streak plate is to produce well separated colonies. It is essentially a dilution technique that involves spreading a loopful of culture over the surface of an agar plate. The streak plate method is a rapid qualitative isolation method. The goal is to obtain isolated colonies on a large part of the agar surface, so that desired species can then be brought into pure culture. Perform a streak plate to separate the cells of a mixed culture so that discrete colonies can be isolated. Although useful, this method also suffers from several important limitations. The streak plate culture technique for the isolation of microorganism is the most practical method of obtaining discrete and welldeveloped colonies of the microbe in pure cultures. This is useful when you need to separate organisms in a mixed culture or when you need to study the colony morphology of an organism. The streakplate procedure is designed to isolate pure.
By using streak plate technique to spread a clinical sample out on the surface of a solid growth medium individual types of bacteria can be isolated. Welcome to microbugz streak plate method of isolation. Tape the plate closed and incubates the plate in an inverted position in an incubator for 2448 hours. In practice, a gradient of cells is established on the surface of an agar plate.
Pick an isolated colony from the agar plate culture and spread it over the first. Streak plate virtual interactive bacteriology laboratory. These colonies can be used to help identify the organism, purify the strain free of. A streak plate involves the progressive dilution of an inoculum of bacteria or yeast over the surface of solidified agar medium in a petri dish.
In this technique, a serially diluted specimen containing 2 or more bacteria or microbe mixed culture is used which is spread over the solidified agar media plates as a thin layer with the help of a sterile lshape glass rod spreader while the media plate is spun on a turntable. Which of the following techniques is not used to isolate bacteria and develop a pure culture. Aug 15, 2019 spread plate technique principle, procedure and uses. Most microbiologists repeat streaking from an isolated colony two to three times before they guarantee culture purity. All strokes of the loop or needle are done in a single forward direction, rather than in a backandforth pattern, as indicated by the arrowhead directions. In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often.
This stain should be repeated when pure cultures are isolated. The plate needs to be dry and at room temperature so that the agar can absorb the bacteria more readily. Samples can then be taken from the resulting colonies and a. Continuous streak method d mark your agar plate into two halfcircles. Comparison of the pour, spread, and drop plate methods for. One way to find microorganisms that may be producing antibiotic compounds is the crowded plate technique. In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. They allow bacteria and fungi to grow on a semisolid surface to produce discrete colonies. Pour plate technique for bacterial enumeration david b. To obtain isolated microbial colonies from an inoculum by creating areas of increasing dilution on an agar petriplate. This manual has been written for a righthanded person. Area of initial inoculation and the first streak yields heavy growth. Refer to aseptic techniques before starting this or any other microbiology practical work. Streaking technique to obtain pure cultures the skin and many mucosal surfaces of the human body support large numbers of microorganisms that comprise the normal, or indigenous, flora.
Pdf lab report of microbiology akbar haqi academia. To insure a countable plate a series of dilutions should be plated. Remove the lid from the first agar plate and place the exposed agar portion in or out of the building for the duration of todays lab. The lid of the agar plate has to be opened just sufficiently enough to streak the plate with the inoculation loop. Streak plate technique is used to grow bacteria on a growth media surface so that individual bacterial colonies are isolated and sampled. The following points highlight the top six methods used for obtaining pure culture of microorganisms.
The streak plate method of isolation means to spread the microbes on plated agar media so that the individual cells or colony forming units cfus can become isolated and grow into individual, pure colonies. One of the most important techniques you will learn this semester is how to streak for isolation. An introduction to microbiology, aseptic technique and safety. Sep 25, 2019 the dilution of microbes is very important to get to microbes diluted enough to count on a spread plate described later. Learn vocabulary, terms, and more with flashcards, games, and other study tools. This allows for individual colonies to be isolated from other colonies. Jun, 2018 yet, many bacterial groups of the termite gut microbiome have not been successfully cultivated in laboratory. Western nevada college biology 251 laboratory manual. These characteristics make it difficult to purify single colonies by the streak plate technique.
Difference between streak plate and spread plate compare. Use pourplating and spreadplating methods to determine the concentration of. Spread plate technique principle, procedure, advantages. In order to illustrate that microorganisms are all around us and to demonstrate the necessity for proper aseptic technique, contaminate three trypticase soy agar plates as follows. Objectives to demonstrate good aseptic technique in culture transfer or inoculation and in handling sterile materials. The spread plate technique involves using a sterilized spreader with a smooth surface made of metal or glass to apply a small amount of bacteria suspended in a solution over a plate. Spread plate technique principle, procedure and uses. The links on this page provide the virtual microbiology classroom documents, web pages and videos useful in preparing for this lab.
An introduction to microbiology, aseptic technique and safety preparation safety guidelines 1 risk assessment 2 good microbiological laboratory practice gmlp 3 spillage management 3 aerosols 3 resources equipment 4 apparatus 5 materials 5 media, sterilisation and disinfection preparation of culture media 6 pouring a plate 6 storage of media 6. These compounds could potentially be toxic to humans, and they may be lethal only to certain types of bacteria e. Pure culture technique preparing a streak plate objectives xemploy the streak plate technique to produce individual colonies on an agar plate. Harnessing microfluidic streak plate technique to investigate. In this study, we adapted the recently developed microfluidic streak plate msp technique for cultivation of termite gut microbial communities at both aerobic and anaerobic conditions.
An introduction to microbiology, aseptic technique and safety preparation safety guidelines 1. The techniques commonly used for isolation of discrete colonies initially require that the number of organisms in the inoculums be reduced. May 11, 2012 these characteristics make it difficult to purify single colonies by the streak plate technique. From a mixture of microorganisms, the student will inoculate an agar plate using this technique, thereby producing isolated colonies. This is the key difference between streak plate and spread plate. The inoculum is streaked over the agar surface in such a way that it thins out the bacteria. Spread plate technique is a method employed to plate a liquid sample for the purpose of isolating or counting the bacteria present in that sample. Streaking microbial cultures on agar plates agar streak plates are an essential tool in microbiology. To demonstrate skill in isolation of organisms from a mixed culture using selective and differential media.
In order to obtain wellisolated discrete colonies, the quadrant streak technique should be used. Full text get a printable copy pdf file of the complete article 209k, or click on a page image below to browse page by page. The technique essentially dilutes the number of organisms and reduces their density. With the pour plate technique, the colonies form within the agar as well as on the surface of the agar medium thus providing a convenient means to count the number of viable cells in a sample. Principle the streak plate technique is essentially a method to dilute the number of organisms, decreasing the density. Crowded plate techniques in microbiology sciencing. Streak plate 11 pour plate 12 using a spreader spread plate 14 working with moulds 15 incubation 16 in conclusion. Some individual bacterial cells are separated and well spaced from each other. To be effective, the dilution of the original sample must be arranged so that on average between 30 and 300 colonies of the target bacterium are grown. Two common isolation techniques streak plates pour plates. These colonies can be used to help identify the organism, purify the strain free of contaminants, and produce a pure genetic clone. In streak plate culture method, a sterilized loop or transfer needle is dipped into the mixed culture of the specimen.
Check out the spread plate culture technique for isolating the microorganism. A common method for the isolation of a pure culture from a mixture is by streaking plates. The streak plate method is a rapid and simple technique of mechanically diluting a relatively large concentration of microorganisms to a small, scattered population of cells. Nov 11, 2018 in microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. Perform a streakplate to separate the cells of a mixed culture so that discrete colonies can be isolated. Ideal results require that only a small amount of inoculum be used and that the surface of the plate be free of droplets of condensed. Study 23 terms streakplate and spreadplate techniques. Pick an isolated colony from the agar plate culture and spread it over the first quadrant. It allows microbiologists to distinguish and isolate individual bacterial colonies. Perform a pour plate loop dilution to separate cells of a mixed culture and compare growth characteristics beneath and on. As you might guess, the purpose of streaking for isolation is to produce isolated colonies of an organism on an agar plate.
The drop plate method was preferred because of its economy in materials and labor. In essence, the streak plate technique is a type of dilution scheme in which a single colony presumably arises from a single cell. A drawing representing the streak pattern recommended by pelczar and reid 8. When clinical specimens are collected from these surfaces and cultured, any pathogenic microorganisms being sought must be recognized among, and isolated from. These objections cannot be raised against the streak plate method. Isolation streak plate technique overview the isolation streak plate technique is a crucial procedure for the microbiology laboratory that enables the generation of pure cultures. Successful streaks lead to individual colonies of microbes. Streak plate technique is used for the isolation into pure culture of the organisms mostly bacteria, from mixed population. Aseptic technique, dilution, streaking, and spread. Quadrant streaking showing the colonies thinning as the streaking moves clockwise. The inoculum is streaked over the agar surface to isolate colonies on at least a portion of the plate. The colony becomes visible to the naked eye and the number of colonies on a plate can be counted. A template for the streak plate isolation technique for laboratory classrooms. Streaking is a method that isolates a pure strain from a species of bacteria.
The streakplate procedure is designed to isolate pure cultures of bacteria, or colonies, from mixed populations by simple mechanical separation. Full text get a printable copy pdf file of the complete article 364k, or click on a. Basic practical microbiology why microbiology matters. A perfect spread plate technique will results visible and isolated colonies of bacteria that are evenly distributed in the plate and are countable. Fankhauser, phd 5 july 1989, rvsd 18 july 93, 21 july 95, 23 july 96, 21 july 97, 17 july 98, 28 jan 00, 28 june 02, 23july09, 22july10. Single colonies are comprised of millions of cells growing in a cluster on or within an agar plate figure 1. Start studying streak plate and spread plate techniques. The crowded plate technique only detects microorganisms that produce compounds to kill bacteria found in their immediate environment. Sterilize the inoculating loop in the bunsen burner by clicking on the loop and dragging it to the burner.
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