Why od 600 for bacteria

Learn how your comment data is processed. Facebook Twitter LinkedIn More. Written by Dr Nick Oswald. Log in to Reply. Leave a Comment Cancel Reply You must be logged in to post a comment. Share via. This will give you a strong sense of how long it takes for your culture to be ready to harvest and provides historical data for comparing bacterial culture growth curves. From the relatively simple OD measurement to metabolite analysis, there are a plethora of ways to keep tabs on your growing bugs in the lab.

Because the growth stage affects much within a culture, knowing how to accurately measure this parameter is a key technique in any bacterial lab! Do you have any tips for OD measurements or bacterial culture growth monitoring? Tell us in the comments below! Has this helped you? Then please share with your network. If you are measuring a hazardous species such as Mycobacterium tuberculosis, you can buy little cuvette caps to keep things contained when you bring the samples out to measure.

Otherwise use Parafilm to seal the tops. Another option is to buy a small little battery-powered spectrophotometer and just keep it inside the BSC. Facebook Twitter LinkedIn More. Written by Adrienne Huntress. Share via. Copy Link. To reduce the required volume for the OD measurement and to avoid time-consuming and error-prone manual dilutions, special cuvettes are available for the researcher. Click on the link below to access a spreadsheet OD Tool, Version 1. Once instrument calibration and standard curve have been established, it can easily be used to document growth experiments for any type of cell culture.

Download OD Tool. Implen, based in Munich, Germany, is a leading supplier for innovative spectroscopy instruments and consumables for the non-destructive analysis of liquid samples offering a complete range of spectrophotometers for cuvette and drop measurements.

The OD Basics Optical Density OD measurements of microbial and cell growth are one of the most common methods used in a microbiology lab. Bacterial growth curve Light scattering of turbid sample Light absorption of clear sample. Therefore, if results from different spectrophotometers are to be compared, they must be normalized first by either a simple correlation of the OD readings using the same sample on the two different instruments to compare or with a more precise approach by the creation of appropriate calibration curves.

Higher absorbance reading Lower absorbance reading. Linear Range for OD Measurements The linear range of the instrument used for the measurements is critical to cover the entire growth cycle of the culture, an OD limit of at least 2. The method requires approximately 1. Alternatively, microplates can be used to continuously monitor microbial growth.

As there are typically 96 wells in a microplate it is perfectly suited to measure multiple samples in replicates and to compare different media conditions or strains. For mid- to high-throughput applications, processes can be automated. An example is shown in the video below. The measurement of light scattering by particles using the absorbance mode may give different results from one instrument to another.

The reason is that different instruments use different light beams and the detector is positioned at different distances from the sample. Think of a light beam being scattered by a microorganism: a nearby detector still captures the light, while a detector positioned further away does not Figure 3. Therefore, choosing one instrument series for microbial growth measurements by OD is recommended. Clearly, the decision for cuvettes or microplates narrows the choice as either a cuvette spectrophotometer or a microplate reader is required.

Instruments that perform both, cuvette and microplate measurements, such as the SPECTROstar Nano are an alternative that equips you for all future needs. For the measurement, microorganism suspensions with known microorganism concentrations are prepared and OD is measured at the instrument of choice using the same volume as used in later experiments. The measured values can then be used to generate a calibration curve.

OD values of unknown samples can later be related to this curve and the concentration can be back calculated. As the light-scattering changes with the size and shape of particles it is recommended to repeat calibration for each organism of interest. Likewise, a calibration needs to be performed when changing the analysis instrument or the sample volume.

The measurement of microbial growth by OD in microplates is increasingly used in combination with detection modes such as luminescence or fluorescence. The measurement of microbial growth serves as normalization for another functional assay.

A beta-galactosidase reporter was measured using a fluorescence readout and the signal indicating enzyme activity was normalized to OD Another example monitored L. The nephelometric method to measure microbial growth is also based on the light scattering of microorganisms. Contrary to OD measurements where the loss of transmission due to scattering is measured, nephelometry directly detects the scattered light. Compared to the absorbance-based method, nephelometry is more sensitive and detects lower amounts of particles, therefore being suitable to suspensions with very low microorganism numbers.

A fluorophore such as GFP or RFP stably expressed by the microorganism of interest is capable of reporting on microbial growth. Fluorescence intensity is linear to the fluorophore concentration.