Bacteria can be hard to identify on an unstained microscope slide. Bacteria are difficult to identify under a brightfield microscope because they lack color, are small and also transparent. In other words, bacteria often look similar to the background they are floating around in. Amateur microscopists may also have trouble distinguishing between bacteria and dust or debris in the sample.
The two solutions for the tricky problem of viewing bacteria involve one of the following:
- Staining the microscope slide.
- Using a phase contrast microscope.
Microscope cell staining is a technique used to enable better visualization of cells and cell parts under the microscope. By using different stains, bacteria or a cell wall are easier to identify. Most stains can be used on non-living (fixed) cells, while only some types of stain can be used on living cells.
There is an extensive list of the types of stains and those that can be used on living cells here.
Phase contrast microscopes allow researchers to observe differences between structures that have a similar level of transparency. By eliminating the need for time-consuming staining, phase microscopes allow research to be conducted more quickly and efficiently. A phase contrast microscope is different from a brightfield microscope in three ways. The phase contrast microscope utilizes a phase contrast condenser, phase contrast objective lenses and a phase centering telescope to center the condenser.
You can learn more about phase contrast and centering the phase contrast condenser here.
