To grow a culture of bacteria, researchers typically use an incubator. The so-called non-gassed or microbiological incubators come in many styles, and usually provide temperature options of 5 to 70 degrees Celsius, although most researchers grow bacteria at 37 degrees Celsius. Yeast, on the other hand, usually grows better at 30 degrees Celsius. Differences like these drive the need for accurate temperature control in a microbiological incubator. Moreover, the specifics of an experiment and even user preferences impact this product market. Like a chef selecting an oven, researchers know what they want from an incubator.
Kristof O’Connor, director of marketing and business development at Boekel Scientific (Feasterville, PA), describes a non-CO2 incubator as “a durable good in the lab environment.” He adds, “It’s similar to a microwave oven or a toaster in a kitchen in that almost everybody has one. It’s not a want to have, but a need to have.” In a Lab Manager Magazine product survey on incubators in 2011, for example, only 14 percent of the respondents were not using an incubator. Moreover, 44 percent of the incubators being used were microbiological ones, versus 53 percent being CO2 incubators.
Overall, says O’Connor, “The majority of these incubators hold samples in plates, Erlenmeyer flasks, or other vessels.” He adds that some researchers also agitate some samples during incubation. It all depends on what grows cultures best.
Control and contamination
The method of heating in a microbiological incubator comes from gravity or convection. The basics of the technology tend to be fairly standard: A thermocouple in the chamber measures the temperature, and that device keeps the temperature in the chamber within some tolerance range by turning on the heating element when the temperature falls below the tolerance and turning it off when the temperature climbs above the tolerance. “The tolerance is getting smaller,” says O’Connor.
In purchasing a device to keep samples at some temperature, “consider the specification that you need, not what the product is called,” says Uwe Ross, president at BINDER (Bohemia, NY). For example, he points out that “some incubators go up to 100 degrees, which means that some low-temperature oven applications that need high accuracy can be run in an incubator.” So when choosing between an oven and an incubator, consider all of the possible uses.
For any use, researchers worry about contamination in growing biological samples. First, researchers want to prevent contamination. Second, they want the easiest options for sterilizing an incubator between uses. Some microbiological incubators include decontamination technology, such as a one-touch button—almost like a self-cleaning oven—that heats the chamber to a higher level, such as 140 degrees Celsius in some models.
In selecting a microbiological incubator, researchers choose between a few more features than just gravity of convection heating. Some incubators come with solid doors and others include a window. In addition, some of the devices use analog controls and others use digital ones. In general, convection units cost more than gravity-based ones. Likewise, the cost also tends to increase with the size of the incubator as well as the temperature range.
“Certain applications are driving people to get incubators that are more and more precise,” says O’Connor. “So they want a stable temperature that is uniform.” Uniformity means the consistency of the temperature across the entire incubator chamber. “This is called chamber mapping,” O’Connor says, “and some researchers want increased levels of this to get finer control.” That way, any plates or vessels inside the incubator experience the same environment.
Beyond heating, an incubator might also need to cool. “If you want to run an incubator at 25 degrees Celsius, which can be less than room temperature in the summer, you need a refrigerated incubator,” says Ross. Of the respondents in the incubator survey, 19 percent were using cooling devices with their incubators.
Incubator users often look for very specific features. For example, David B. Fankhauser, PhD, professor of biology and chemistry at University of Cincinnati Clermont College in Ohio, looks for several features in a microbiology incubator. He looks for a double door with glass on the inside. He also wants an “easy-to-use latch that is secure when closed.” Inside, the shelves should be “easily moved or removed,” Fankhauser says. Plus, he wants an incubator that is “large enough to easily accommodate a tray of at least five stacks by five stacks of plates.” In terms of operation, Fankhauser wants an incubator that includes “closeable vents, which are open when drying plates, but closed when you do not want the plates to dry.” Last, he also likes a microbiological incubator to provide a digital readout to the nearest 0.1 degree Celsius.
In many cases, cost makes up the key feature in the microbiological incubator market, says O’Connor, “because of its commodity nature.” Likewise, adding features to these incubators typically adds to the price.
Increasingly, incubators get used in food and water testing, says Ross. “We will see that testing for contamination and shelf life will become more important,” he says.
As incubators get used for more quality assurance and control, the required sample volume might trigger the need for automation. “You see some companies that come up with, let’s say, robots attached to chambers, like an oven or incubator, and specific applications where that is beneficial, but that’s in its infancy,” says Ross. “There’s no automated incubator that a lab can buy and adjust to their needs.”
Although it might seem easy enough to keep a culture at just the right temperature, today’s research requires even more features from microbiology incubators. In fact, specific users find some features more important than others. Overall, though, a device that grows culture consistently and without contamination matters the most.