This article details a method for measuring bacterial metabolism using isothermal microcalorimetry. By correlating metabolic heat production with optical density, researchers can analyze bacterial growth dynamics.
Take serial dilutions of a bacterial culture and add aliquots into calorimetric vials containing growth medium.
Load the sealed vials into the multi-well plate of an isothermal microcalorimeter to measure metabolic heat production.
The device is held at a constant temperature to ensure the detected heat originates solely from bacterial metabolism.
As bacteria metabolize nutrients and proliferate, they release heat that sensors detect in real time.
In parallel, incubate identical vials in an incubator. Using a spectrophotometer, measure the optical density (OD) to monitor bacterial growth.
Using the calorimetric signals from the dilutions, construct a thermal activity curve and correlate it with OD values.
A sharp first peak indicates aerobic respiration during exponential growth.
As oxygen becomes limiting, cells shift to anaerobic fermentation, producing a second sharp peak.
Upon entering the stationary phase, the bacteria secrete enzymes to degrade extracellular proteins and sustain metabolism, producing a broad peak.
繁體中文
