Streak plate technique streaking is the process of spreading the microbial culture with an inoculating needle on the surface of the media. Students may repeat the streak plate procedure above with two other tsa plates. Difficult to distinguish from other debris in a smear. Starting the streak on the side of the plate farthest from your dominant hand, pass the loop on the surface of the. The idea behind the quadrant method is to obtain well isolated colonies, and to do this, you must streak the agar plate in a way to decrease the density of organisms with every streak cycle. Streak plate technique is used for the isolation into pure culture of the organisms mostly bacteria, from mixed population. Bring bapmac plates and a chrome plate to room temperature. Bacterial culture streaking allows bacteria to reproduce on a culture medium in a controlled environment. Streak plate virtual interactive bacteriology laboratory. The following methods are used to isolate pure culture. Lab 2 isolation the streak plate method flashcards. Isolation of bacterial colonies using the quadrant method the streakplate procedure is designed to isolate pure cultures of bacteria, or colonies, from mixed populations.
The dilution or isolation by streaking procedure was originally developed by loeffler and gaffky in kochs laboratory, which involves the dilution of bacteria by systematically streaking. Immediately streak the inoculating loop very gently over a quarter of the plate using a back and forth motion see area 1 in the figure below. When attempting to isolate a specific type of bacteria from a clinical sample, this streak plate technique will need be repeated, possibly several times, in order to obtain a pure sample. Cool the loop by touching it on the edge of the sterile agar plate. The modern pour plate culture method was initially developed in the laboratory of the famous bacteriologist and the father of bacteriology, dr. Pour plate technique for the isolation of microorganism. Incubate and enumerate as directed in product instructions. Label the bottom of the plate with the above data plus initials, seat number and date. Quadrant streaking showing the colonies thinning as the streaking moves clockwise.
The method most often used in the clinical laboratory is the quadrant method. This allows for individual colonies to be isolated from other colonies. Streaking microbial cultures on agar plates science buddies. We also acknowledge previous national science foundation support under grant numbers. Aseptic technique, dilution, streaking, and spread. Streak plate technique is used to grow bacteria on a growth media surface so that individual bacterial colonies are isolated and sampled. The techniques commonly used for isolation of discrete colonies initially require that the number of organisms in the inoculums be reduced.
For the one plate, streak the mixed culture solely in one direction across the entire plate in one long motion. Urine cultures are evaluated with consideration given to factors such as colony count, type and number of organisms growing, type of specimen and the clinical condition of the patient. In the pour plate method a diluted bacterial sample is mixed with melted agar and then that mixture is poured into a petri dish. The process involves spreading bacteria across an agar plate and allowing them to incubate at a certain temperature for a period of time. In the streaking procedure, a sterile loop or swab is used to obtain an uncontaminated microbial culture. Streak plate method principle, methods, significance, limitations. The lid of the agar plate has to be opened just sufficiently enough to streak the plate with the inoculation loop. In streak plate culture method, a sterilized loop or transfer needle is dipped into the mixed culture of the specimen. Single colonies are comprised of millions of cells growing in a cluster on or within an agar plate figure 1. Spread plate technique principle, procedure and uses. Learn streak plate method with free interactive flashcards.
All the process is done in a laminar air flow cabinet aseptically. A new loop is recommended for each sector of an isolation streak plate. The three sector streak or commonly referred to as the tstreak is a basic, yet crucial skill used by microbiologist on a daily basis to isolate, identify, and study colonies of bacteria. Streaking is a method that isolates a pure strain from a species of bacteria. Serial dilution, pour plates, and enumeration of bacteria introduction the number of bacteria in a small sample can be startling.
Pick an isolated colony from the agar plate culture and spread it over the first. A common method for the isolation of a pure culture from a mixture is by streaking plates. Preparation for the pour plate method is time consuming compared with streak plateand or spread plate technique. Streak the plate, following either the tmethod or quadrant streak shown below.
Repeat onto a new plate until the entire sample is used. Bacterial streaking can be used to identify and isolate pure bacterial colonies from a mixed population. Streak plate technique for isolation of microorganism. Make a second tstreak from a different pure culture, labeling the plate as instructed. The streakplate procedure is designed to isolate pure. Dip the loop into the broth culture containing the mixture of bacteria. What is critical is the generation of isolated colonies. The modern streak plate method has evolved from the efforts by robert koch and other microbiologists to obtain pure culture of bacteria in order to study them. This picks up a small number of bacteria from the first section and transfers them to the second section. 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. Drop plate technique has a priority and preference compared with the spread plate procedure, because of less time, quantity of media, effort requirement, little incubator space, and less labor intensive. 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. Sterilize the inoculating loop in the bunsen burner by clicking on the loop and dragging it to the burner.
Pdf lab report of microbiology akbar haqi academia. Streak plate method principle, methods, significance. Transfer to the growth media as quickly as possible. Isolation of bacterial colonies using the quadrant method. Microbes in action this material may be duplicated by teachers for use in the classroom. This presents microbiologist with an interesting challenge obtaining isolated colonies of bacteria in a method that is both simple and rapid. Minimize the amount of agar and the length of time the agar is exposed to the environment during the streak process. The streak plate method is a rapid qualitative isolation method for obtaining discrete colonies from a mixed population. It is essentially a dilution technique that involves spreading a loopful of culture over the surface of an agar plate. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. For the other tsa plate, using the above procedure as a guide, perform the streak plate using the fourphase method. 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.
In order to obtain wellisolated discrete colonies, the quadrant streak technique should be used. The streak plate method is a rapid qualitative isolation method. If more than one shape or colour of colony on the streak lines is evident, this indicates that a culture contains more than one type or species of bacterium or yeast. Other methods are also used, but in this lab, we will use this method for practical purposes.
The inoculum is streaked over the agar surface to isolate colonies on at least a portion of the plate. Choose from 500 different sets of streak plate method flashcards on quizlet. In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. The exact streak plate method that one uses to generate isolated colonies is not too critical. 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. Samples can then be taken from the resulting colonies and a culture can be grown on a new plate so that the organism can be. The most common method of separating bacteria cell on agar surface to obtain isolated colonies is the streak method to inoculate petri dish. Streaking microbial cultures on agar plates, page 2 1999 science in the real world. Obtaining a pure culture of bacteria is usually accomplished by spreading bacteria on the surface of a solid medium so that a single. Do not gouge into the medium with the loop and keep the lid over the plate as much as possible.
The colonies on the plate can then be counted and the concentration of bacteria in the original culture can be calculated. This method is the most straightforward of the various methods for preparing a streak plate. Most microbiologists repeat streaking from an isolated colony two to three times before they guarantee culture purity. 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. Again the colonies would be counted and the viable cell count calculated. Method of isolation of pure culture linkedin slideshare. Despite the method, the original sample is used to. Described below is the zigzag method of inoculation. The streakplate procedure is designed to isolate pure cultures of bacteria, or colonies, from mixed populations by simple mechanical separation. The links on this page provide the virtual microbiology classroom documents, web pages and videos useful in preparing for this lab. As mentioned in the previous lab, pure cultures are essential for microbiological studies. Principle, purpose, procedure and results july 16, 2016 acharya tankeshwar bacteriology, microbiology for beginners 29 quadrant streaking for isolation into pure culture.
The following points highlight the top six methods used for obtaining pure culture of microorganisms. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or tested the modern streak plate method has progressed from the efforts of robert. Inoculation of agar plates using a swab a sterile swab must be used, care must be taken not to contaminate by touching other surfaces. 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. Spread plate technique methods of isolating pure culture 3. Spread plate technique is the method of isolation and. The aim of the procedure is to obtain single isolated pure colonies. Pour plate technique procedure, significance, advantages, limitations.
Pour plate technique procedure, advantages, limitations. It will not enable you to get a concentration count. This allows sequential dilution of the original microbial material. The inoculum is streaked over the agar surface in such a way that it thins out the bacteria. Going back to the edge of area 1 that you just streaked, extend the streaks into the second quarter of the plate area 2.
The streak plate method does not work with high volumes of organisms. The streak plate technique is the most popular method for isolating specific bacteria from a sample containing a mixture of microorganisms. Depending on your purposes, you can inoculate the swab in a few ways. The number of times this basic procedure is repeated depends on the streak plate method used.
A perfect spread plate technique will results visible and isolated colonies of bacteria that are evenly distributed in the plate and are countable. Principle the streak plate technique is essentially a method to dilute the number of organisms, decreasing the density. Competence and level of training in techniques and procedures appropriate to level. 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. Principle, procedure and results july 28, 2017 nisha rijal bacteriology, microbiology for beginners 7 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. The streak plate method is convenient and hasslefree as you will be able to get visible individual colonies in a single petri plate for as long as you have a good streaking skill. The streak plate method is a rapid and simple technique for obtaining wellisolated colonies on the surface of the plate, each arising hopefully from a single cell, so that pure cultures from a mixture can be established. Basic practical microbiology why microbiology matters. There are alternative methods for preparing a streak plate but the method. Start studying lab 2 isolation the streak plate method.
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