lagvaihe

Lagvaihe, commonly translated as the lag phase, is the initial stage of microbial growth after inoculation into fresh culture medium. During this phase, cells adapt to the new environment and there is little or no net increase in cell number, though metabolic activity is high as cells synthesize RNA, enzymes, and membrane components needed for growth.

The duration of the lag phase, or lag time, varies widely. It depends on the species, the physiological state of the inoculum (for example, whether cells are in a stationary or active growth state), prior growth conditions, and environmental factors such as temperature, pH, oxygen levels, and nutrient composition. Stresses or inhibitors in the medium can extend lag time, while rich or gradually acclimated conditions can shorten it.

In growth curve analysis, lag time is estimated from the transition between the lag phase and the exponential (log) phase. Various mathematical models are used, including Baranyi, Gompertz, and logistic models, to quantify lag time and other growth characteristics. The lag phase is distinct from subsequent phases, with the exponential phase characterized by rapid cell division and the stationary phase by slowed growth due to resource depletion.

Applications and relevance include food microbiology and industrial fermentation, where lag time influences detection times, shelf life, and production scheduling. Strategies to reduce lag time include using pre-adapted starter cultures, increasing inoculum size, optimizing pre-culture conditions, and acclimating cultures gradually to production temperatures.