Which process utilizes a spectrophotometer at 600 nm?

The process of calculating bacterial concentration in liquid culture is commonly accomplished using a spectrophotometer set at a wavelength of 600 nm, often referred to as the optical density (OD600) measurement. At this specific wavelength, the spectrophotometer measures the turbidity of the liquid culture, which correlates with the number of bacterial cells present. As the concentration of bacteria increases, the culture becomes more turbid, resulting in higher absorbance readings at 600 nm. This method is widely used because it allows for a quick and non-destructive estimation of bacterial growth, making it easier for researchers to monitor growth rates or adjust conditions in their experiments.

The other processes listed, such as streaking bacteria on solid media, creating slant cultures, and inoculation of media, involve handling and culturing techniques that do not require the use of a spectrophotometer. Therefore, the focus on measuring absorbance at 600 nm directly pertains to assessing the concentration of bacteria within liquid cultures.