Streak Plate Method
Streak Plate Method - Related Videos
09:03
Pure Cultures and Streak Plating: Isolation of Single Bacterial Colonies from a Mixed Sample
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2023
Source: Tilde Andersson1, Rolf Lood1 1 Department of Clinical Sciences Lund, Division of Infection Medicine, Biomedical Center, Lund University, 221 00 Lund, Sweden Seemingly impossible to determine, microbial biodiversity is truly astounding with an estimated one trillion coexisting species (1,2). Although particularly harsh climates, like the acidic environment of the human stomach (3) or the subglacial lakes of Antarctica (4), may be dominated by a specific species, bacteria are typically...
18:00
Aseptic Laboratory Techniques: Plating Methods
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Cited by 438 •
2012
When working with media and reagents used to culture microorganisms, aseptic technique must be practiced to ensure contamination is minimized. A variety of plating methods are routinely used to isolate, propagate, or enumerate bacteria and phage, all of which incorporate procedures that maintain the sterility of experimental materials.
10:53
Serial Dilutions and Plating: Microbial Enumeration
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2023
Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1 1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301 Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific physiological needs. Compounding this challenge, is the four-phase nature in which bacteria replicate (lag, log, stationary and death). The ability to accurately...
11:31
Determination of Impingement Forces on a Flat Plate with the Control Volume Method
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2023
Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI The purpose of this experiment is to demonstrate forces on bodies as the result of changes in the linear momentum of the flow around them using a control volume formulation [1, 2]. The control volume analysis focuses on the macroscopic effect of flow on engineering systems, rather than the detailed description that could be achieved with a differential...
05:16
A Microtiter Plate Method to Assess the Minimum Inhibitory Concentration of an Antibiotic
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2025
This video demonstrates a microtiter plate-based method for determining the Minimum Inhibitory Concentration (MIC) of test antibiotics against bacteria. Upon adding a suspension of the bacterial pathogen Pseudomonas aeruginosa to a microtiter plate containing serial dilutions of a test antibiotic, and an inhibitor of the production of pyomelanin by the bacteria, the optical density of the wells is measured to compute the minimum inhibitory concentration of the antibiotic, and the impact of the...
FAQs
Its central mechanism is progressive physical dilution across the agar surface. A small inoculum is distributed through successive plate sections, so fewer cells remain in each later area. Where individual cells become sufficiently separated, they can multiply during incubation without merging with neighboring growth. This spatial separation makes individual colonies available for examination and further work.
The sterile inoculating loop transfers the sample and distributes it across the agar while limiting the introduction of unrelated microorganisms. Because isolation depends on the growth arising from the transferred sample, maintaining sterility supports reliable interpretation of the resulting colonies. The loop also enables the small, controlled inoculum needed for progressive dilution across the plate.
Using a small sample helps prevent the plate from remaining uniformly crowded after the first spreading step. As that inoculum moves through successive sections, the cells become increasingly dispersed. This progression increases the chance that individual organisms occupy separate locations and later produce distinct colonies, which is especially important when beginning with a mixed or dense culture.
Colony morphology provides visible characteristics that researchers can examine after growth occurs on solid medium. These observations support preliminary identification and help distinguish colonies within a mixed culture. Morphology alone does not replace further analysis, but it helps researchers select separated growth and assess whether the plate has produced material suitable for purification or additional testing.
A researcher places a small sample onto solid growth medium and uses a sterile inoculating loop to spread it through successive sections of the agar plate. The repeated distribution progressively separates the cells across the surface. After incubation, growth can be examined for distinct colonies, which may then support purification, preliminary identification, or further testing.
An isolated colony can provide a source of clonal culture, meaning growth derived from separated microbial cells. This material is useful for examining colony morphology and carrying out subsequent testing or analysis with less interference from neighboring organisms. The method therefore serves as an important preparation step when a mixed culture must be studied as separate microbial populations.
The method is used wherever reliable microorganism isolation is needed. In clinical microbiology, environmental studies, and quality control, separated colonies support examination and further analysis of organisms from mixed or dense cultures. More broadly, biology laboratories use the approach for purification and preliminary identification of bacteria and fungi before additional work is performed.