What technique is used to distinguish between the various types of bacteria?

Not all bacteria can be identified through gram staining
but it is usually the first step taken. It is a fairly simple technique that labs use
all of the time. Gram staining splits the bacteria into two groups which are gram
negative and gram positive.

Another method used to identify
bacteria is phase contrast microscopy. This method is sometimes used because individual
bacteria are very hard to see, in fact they appear to be transparent. A special
microscope is used and through illumination light passes through the bacteria and
amplitude and contrast are used to make the bacteria visible and able to be
viewed.