Maintaining organisms or samples under controlled conditions to promote growth or development
Explanation
In microbiology and cell biology, incubation refers to the period during which cultures, eggs or biochemical reactions are kept at specific environmental conditions to allow growth, replication or maturation. Temperature is the most critical factor, with many human pathogens cultured at 37 °C and environmental organisms at lower or higher settings. Humidity, carbon dioxide concentration and oxygen levels are also regulated, particularly in mammalian cell culture, where incubators maintain 5 % CO2 to equilibrate media pH. During incubation, microorganisms synthesize proteins, replicate DNA and divide, while vertebrate embryos undergo cell differentiation and organ development. In immunoassays and enzymatic reactions, incubation allows antibodies to bind antigens, enzymes to catalyze substrates or nucleic acid probes to hybridize. Controlling contamination is essential; incubators often include HEPA filters and antimicrobial surfaces. Incubation duration varies widely—from minutes for enzymatic assays to days or weeks for culture growth—and is determined by the organism’s growth rate and experimental goals.
Practical examples
In clinical microbiology laboratories, throat swab cultures for Streptococcus pyogenes are incubated on blood agar plates at 35–37 °C in 5 % CO2 for 18–24 hours before evaluation. Yeast cultures may be incubated at 25–30 °C for several days. Mammalian cell lines such as HeLa are grown in humidified incubators at 37 °C with 5 % CO2. During enzyme‑linked immunosorbent assays, samples are incubated with capture antibodies, washed and incubated with detection antibodies to allow binding. In developmental biology, bird or reptile eggs are incubated at constant temperature to ensure proper embryo development. The incubation step is also crucial in polymerase chain reaction, where DNA polymerase extends primers during set temperature cycles.
Incubation is fundamental to experimental biology and diagnostics, providing the environmental stability needed for biological processes to proceed optimally.
Related Terms: Incubator, Culture, Cell culture, Incubation period, Incubate