[Microbiology] Atlas of Streak Plate Methods of Isolation

Streak Plate Methods of Isolation, Isolation Techniques and Selective Media, A Photographic Atlas for the Microbiology Laboratory,



Purpose
The identification process of an unknown microbe relies on obtaining a pure culture of that organism. The streak plate method produces individual colonies on an agar plate. A portion of an isolated colony then may be transferred to a sterile medium to start a pure culture.

Principle
A microbial culture consisting of two or more species is said to be a mixed culture, whereas a pure culture contains only a single species. Obtaining isolation of individual species from a mixed sample is generally the first step in identifying an organism. A commonly used isolation technique is the streak plate.

In the streak plate method of isolation, a bacterial sample (always assumed to be a mixed culture) is streaked over the surface of a plated agar medium (Figure 2-1). During streaking, the cell density decreases, eventually leading to individual cells being deposited separately on the agar surface. Cells that have been sufficiently isolated will grow into colonies consisting only of the original cell type. Because some colonies form from individual cells and others from pairs, chains, or clusters of cells, the term colony-forming unit (CFU) is a more correct description of the colony origin.

A common streaking technique is the quadrant method, which uses the four-streak pattern shown in Figures 2-2 and 2-3. Streaking for isolation is frequently performed on selective media 

STREAKING A PLATE
2-1 STREAKING A PLATE Hold the plate comfortably
and streak with the edge of the loop. Be careful not to cut
the agar.  


THE QUADRANT METHOD
2-2 THE QUADRANT METHOD As shown, the
quadrant method of streaking for isolation involves
four individual streaks. The best results are obtained
when the loop is flamed between streaks.

designed to encourage growth of certain types of organisms while inhibiting growth of others. The selective media considered in this section are used specifically to isolate pathogenic bacteria and yeast from human or environmental samples containing a mixture of organisms. Some selective media contain indicators that expose differences between organisms.

Such media are considered to be selective and differential. See Tables 2-1, 2-2, and 2-3 for summaries of terms related to organisms and media, and roles of common ingredients found in selective media.  

STREAK PLATE OF SERRATIA MARCESCENS
2-3 STREAK PLATE OF SERRATIA MARCESCENS Note
the decreasing density of growth in the four streak
patterns. On this plate, isolation is first obtained in the
fourth streak. A portion of an individual colony may be
transferred to a sterile medium to start a pure culture.

TABLE 2-1: Terms Related to Media

TABLE 2-2: Terms Related to Organisms

TABLE 2-2: Common Ingredients in Selective Media and Their Roles


Suggested Reading
- Michael J. Leboffe & Burton E. Pierce. A Photographic Atlas for the Microbiology Laboratory 4th edition 2011



COMMENTS

Name

CLINICAL ATLAS,118,DERMATOLOGY ATLAS,10,EMERGENCY ATLAS,44,HAEMATOLOGY ATLAS,23,HUMAN ANATOMY,1,MICROBIOLOGY ATLAS,66,PARASITOLOGY ATLAS,4,PATHOLOGY ATLAS,22,PEDIATRIC ATLAS,42,STDs,19,SUBCLINICAL ATLAS,116,
ltr
item
Free Medical Atlas: [Microbiology] Atlas of Streak Plate Methods of Isolation
[Microbiology] Atlas of Streak Plate Methods of Isolation
Streak Plate Methods of Isolation, Isolation Techniques and Selective Media, A Photographic Atlas for the Microbiology Laboratory,
https://2.bp.blogspot.com/-vYbiESksFpA/WoBvD_rNakI/AAAAAAAAFMg/z8hzBe8UDjM6Y6eyaJ-nKvHhGTfw_zjlQCEwYBhgL/s1600/vs2.3.jpg
https://2.bp.blogspot.com/-vYbiESksFpA/WoBvD_rNakI/AAAAAAAAFMg/z8hzBe8UDjM6Y6eyaJ-nKvHhGTfw_zjlQCEwYBhgL/s72-c/vs2.3.jpg
Free Medical Atlas
https://www.tuyenlab.net/2018/02/microbiology-atlas-of-streak-plate.html
https://www.tuyenlab.net/
https://www.tuyenlab.net/
https://www.tuyenlab.net/2018/02/microbiology-atlas-of-streak-plate.html
true
3150612095398522649
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share. STEP 2: Click the link you shared to unlock Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy