Place nutrient agar onto three small slides in a petri dish. Nutrient agar can be purchased online or at retail stores and is what many common forms of bacteria feed on.
Take a cotton swab and draw it across a high-use area like a doorknob, table, bathroom or kitchen surface.
Swipe the cotton swab onto the three slides in the dish.
Close the petri dish and wrap masking tape around it to ensure the seal. Place it in a dark area for 5 days.
Take out the slides after 4 days and place them under a microscope, one at a time. You will view each slide.
Identify the bacteria colonies by form. Forms can be circular, irregular, filamentous and rhizoid. Circular and round as well as irregular bacteria are typically under the phylum cocci. Rhizoid and filamentous are typically of the bacteria phylum bacilli.
Identify the bacteria colonies' elevation. Forms include raised, convex, flat, umbonate and crateriform. Examples of these include bacillus subtilis which is flat; staphylococcus epidermidis is convex; escherichia coli is raised; Enterobacter aerogenes is unbonate; enterococcus faecalis is crateriform.
Identify a bacteria colonies' margin, which can be entire, undulate, filiform, curled and lobate. Margin refers to the edge of the colony. Combined with other criteria, margin can help further identify bacteria colonies.
Identify a bacteria colonies' surface by looking at the top layer's texture. It can be smooth, glistening, rough, dull or rugose (wrinkled). Bacteria can be identified when the visible texture and other characteristics are identified. There are thousands of possibilities.
Identify the opaqueness of the bacteria colonies. This includes the categories of transparent, opaque, translucent and iridescent.
Identify the bacteria colonies pigmentation. This can include white, buff, purple and red.
Refer to a manual of determinative bacteriology to determine bacteria type. Once the characteristics have been identified, you can match them with the type of bacteria.