How can you tell whether or not there is bacterial growth in the nutrient broth?
If the broth is NOT cloudy there is unlikely to be bacterial growth in it. The easiest way to see what is in it is to spread onto agar plates- you need to have different types of plate (for example blood agar is a ‘friendlier’ plate for many organisms whereas something like McConkey would be a better one for coliforms). By using a loop to spread out on the plate it is easy to separate colonies of bacteria in order to identify them. A quicker way would be to make a Gram stain of the broth- better after some is centrifuged (more concentrated with bacteria). The stain is then looked at by microscope.
