Detecting bacteria is an important application in laboratories where researchers need to study the growth of a specific microorganism or find out which bacteria are present.
There are several instruments from top manufacturers like SBT that can help you achieve this, but how do you know what instrument is best for your needs? This article will introduce some common bacterial detection methods to help you make an informed decision.
We will consider applications such as:
- Detection of single colonies;
- Detection of live/ dead cells;
- Colony counting (quantification);
- Measurement of colony size/ morphology.
Let’s start by looking at a typical workflow when detecting microbes:
culturing and incubating → plating → measuring colonies on agar plates → counting colonies → data analysis.
Types Of Bacterial Detection Instruments
There are three main types of instruments that can be used for bacterial detection: optical microscopes, colony counters, and plate readers.
- Optical Microscopes
Optical microscopes are used to examine bacterial morphology and size. They have a resolution of around 200 nm, which means that they can distinguish objects about 200 nm apart.
However, optical microscopes are not very efficient for detecting small colonies because the area that can be scanned is limited by the field of view (FOV). In addition, image analysis can be time-consuming and challenging if you need to detect bacteria in complex samples.
- Colony Counters
Colony counters use an automated imaging system to count colonies on agar plates. The advantage of using colony counters is that they can detect colonies down to a size of 0.001 mm².
This makes them ideal for counting small colonies (<100 μm) in high throughput applications. However, colony counters can be expensive and require some training to use correctly.
- Plate Readers
Plate readers are used to measuring the optical density (OD) of bacterial colonies on agar plates. They have a resolution of around 0.02 OD, which means that they can detect changes in OD as small as 0.0002 units.
This makes them ideal for measuring the size and morphology of bacterial colonies. Plate readers are also relatively affordable and easy to use.
So, which instrument is best for your needs?
If you are looking for an instrument that can quickly and accurately count small colonies, then a colony counter is the best option. However, if you need to measure the OD of large colonies (>100 μm), then a plate reader is the best option. We hope this article was helpful!