Incubator / BOD incubator

An incubator provides a stable, uniform temperature for the growth of microorganisms. A standard bacteriological incubator only heats, so it works at temperatures above the room, typically 30–35 °C for total aerobic microbial counts. A BOD (biological oxygen demand) incubator has both a heater and a refrigeration unit, so it can hold temperatures close to or below room temperature, such as 20–25 °C for yeasts and moulds, and remains stable when the room warms up.

Pharmacopoeial microbiology tests specify incubation temperature ranges, for example 30–35 °C for SCDA and 20–25 °C for SDA. Incubators are usually set near the middle of the range (e.g. 32.5 °C or 22.5 °C) so that normal variation across the chamber stays inside the limits. Temperature mapping shows that every shelf position used for plates is within the range.

Incubators in a QC lab are connected to continuous temperature monitoring with alarms. Results from plates incubated outside the required range may not be valid, so excursions must be recorded and assessed.