A spiral plater is an instrument used to dispense a liquid sample onto a

Petri dish A Petri dish (alternatively known as a Petri plate or cell-culture dish) is a shallow transparent lidded dish that biologists use to hold growth medium in which cells can be cultured,R. C. Dubey (2014): ''A Textbook Of Biotechnology For Class- ...

in a

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:CFU count procedure for the purpose of determining the number of microbes in the sample.J. E. Gilchrist, J. E. Campbell, C. B. Donnelly, J. T. Peeler, and J. M. Delaney
"Spiral Plate Method for Bacterial Determination"
'' Appl Microbiol. '', 1973 February; 25(2): 244–252., In this setting, after spiral plating, the Petri dish is incubated for several hours after which the number of colony forming microbes (CFU) is determined. Spiral platers are also used for research, clinical diagnostics and as a method for covering a Petri dish with

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

before placing antibiotic discs for AST.

Mode of action

The spiral plater rotates the dish while simultaneously dispensing the liquid and either linearly moving the dish or the dispensing tip. This creates the common spiral pattern. If all movements are done in constant speed, the spiral created would have a lower concentration on the outside of the plate than on the inside. More advanced spiral platers provide different options for spiral patterns such as constant concentration (by slowing down the spinning and / or the lateral movements) or exponential concentration (by speeding up the spinning and / or the lateral movements).

In food and cosmetic testing

Spiral plating is used extensively for microbiological testing of food, milk and milk products and cosmetics. It is an approved method by the FDA. The advantage of spiral plating is less plates used versus plating manually because different concentrations are present on each plate. This also makes it harder to count the colonies and requires special techniques and equipment.

Stand-alone vs. Add-on

Spiral platers are either available as stand-alone instruments that are fed manually with plates and samples or fed automatically using dedicated stackers. Alternatively spiral platers are available as integrated devices as part of larger automated platforms. In this case a larger workflow is often automated, e.g. plating, incubation and

counting Counting is the process of determining the number of elements of a finite set of objects, i.e., determining the size of a set. The traditional way of counting consists of continually increasing a (mental or spoken) counter by a unit for every ele ...

References

{{Reflist Biological techniques and tools Food safety