Direct comparison
Streak Plate vs Spread Plate vs Pour Plate
Streak plate vs spread plate: one isolates single colonies, one counts cfu/ml. Volumes, tools, heat risks and pour plate differences, from JoVE and FDA BAM.
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How do Streak plate, Spread plate compare side by side?
The table below compares Streak plate, Spread plate across 11 procurement-relevant dimensions, from main purpose through source.
Side-by-side comparison
| Dimension | Streak plate | Spread plate |
|---|---|---|
| Main purpose | Isolates single colonies from a mixed population by mechanical separation; the colonies are generally clonal. | Counts viable cells: between 30 and 300 bacterial cells are spread over the agar surface to give colony-forming units per ml (cfu/ml). |
| Inoculum volume | A loopful, or 5 to 10 µl with a micropipettor. | 0.1 to 0.2 ml with a turntable and spreader, or 100 to 150 µl when sterile glass beads are used. |
| Sample handling before plating | A cell suspension is swirled or vortexed before an aliquot is taken; alternatively a colony from another plate is touched with the loop, stick or toothpick and spread over the first quadrant. | The amount plated is set so that 30 to 300 cells land on the plate, which is what makes the plate countable. |
| Where the colonies grow | On the agar surface, in separated zones as the inoculum is thinned across the quadrants. | On the agar surface, spread across the plate; surface colonies can be picked for a streak plate or a broth culture. |
| Can it be counted? | It is not a counting method; the source gives no colony-count range for streaking. | Yes. The count is read as cfu/ml from plates in the 30 to 300 range. |
| Tools used | A metal loop (re-usable), a disposable plastic loop, or a sterile stick or toothpick, and an agar plate in a Petri dish. | A glass spreader used on a turntable after dipping in ethanol and flaming, or 10 to 12 sterile glass beads dispensed onto the plate, plus a micropipettor and an agar plate. |
| Heat risk | A metal loop is flamed until red hot and must be cooled, for example by touching a spot of the agar away from the inoculum, before it touches a colony. | A hot spreader will kill the cells, so it is cooled by touching the agar near the rim, away from where the cells were added. |
| Typical fault | Forgetting to flame a loop, or to take a fresh toothpick, between quadrants makes it difficult to obtain single colonies. | Uneven spreading: with a turntable, colonies end up only near the centre; with beads, swirling instead of shaking pushes colonies to the rim. |
| Against the pour plate | A pour plate mixes 0.1 to 1.0 ml of sample into melted agar at about 48 °C, so colonies form within the agar as well as on the surface, and it is used to count viable cells. A streak plate is for isolation, not enumeration. | Both count viable cells. Pour-plate colonies embedded in agar are small and irregular and harder to pick; agar that is too hot may kill bacteria and undercount. The FDA's pour-plate method for foods uses 1 ml of dilution in 12 to 15 ml of plate count agar cooled to 45 ± 1 °C, with a counting range of 30-300 (USDA, AOAC), 25-250 (APHA) or 15-300 (ISO) colonies per plate. |
| When to pick it | Pick it when the aim is single, separated colonies from a mixed culture, for example to take a colony forward. | Pick it when the aim is a viable count (cfu/ml) from surface colonies that can still be picked afterwards. |
| Source | Sanders ER, J Vis Exp 2012;(63):3064 (doi:10.3791/3064), read 2026-10-29. | Sanders ER, J Vis Exp 2012;(63):3064; pour-plate figures from FDA BAM Chapter 3: Aerobic Plate Count, January 2026 edition, read 2026-10-29. |
Common questions
Common questions about Streak plate vs Spread plate
What is the difference between a streak plate and a spread plate?
+
A streak plate isolates single colonies from a mixed population by mechanical separation, using a loopful or 5 to 10 µl of inoculum. A spread plate puts 0.1 to 0.2 ml (or 100 to 150 µl with glass beads) over the whole agar surface so that 30 to 300 cells can be counted as cfu/ml.
What is the difference between a streak plate and a pour plate?
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A streak plate isolates colonies on the agar surface. A pour plate mixes 0.1 to 1.0 ml of sample into melted agar at about 48 °C, so colonies grow within the agar as well as on it, and the method is used to count viable cells. Embedded colonies are small and irregular and harder to pick.
Which plating method is used to count colonies?
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The spread plate and the pour plate are the counting methods. Sanders gives 30 to 300 cfu as the statistically significant range. The FDA BAM pour-plate method states 30-300 (USDA and AOAC), 25-250 (APHA) and 15-300 (ISO) colonies per plate.
Why can the agar or spreader temperature ruin a plate?
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Too-hot agar in a pour plate may kill the bacteria in the sample, and a hot spreader in a spread plate will kill the cells. FDA BAM specifies plate count agar cooled to 45 ± 1 °C for its pour-plate method.
Going deeper
