Identification of the unknown bacteria was determined by a series of tests using differential media and Gram staining. These tests revealed information about the motility, metabolism and enzymes of the unknown microorganism. The most basic technique for all testing is called aseptic technique. This technique aims “to prevent contamination of the sample” (Leboffe and Pierce, 2010). This is the first technique taught to students in the laboratory. Aseptic transfers were performed either with an inoculation loop or needle from the microorganism stock to a sterile medium. Sterile media included tryptic soy broth or tryptic soy agar. To avoid contamination, inoculation loops and needles are usually sterilized in the Bunsen burner flame, but in the laboratory a microincinerator has been used instead. Other measures taken to avoid contamination include holding an open test tube at an angle and heating the rim of the tube as well as the surrounding air (Leboffe and Pierce, 2010). Microscopic examination was usually associated with a stain. For example, a Gram stain can be used to identify the shape of the microorganism and how many layers of peptidoglycan it has. Cell shape and type can be used to determine which genera unknown bacteria could be classified into. Differential media have been used to “distinguish between different species of bacteria” (Madigan, Martinko, Stahl, Clark, 2012). Although all species of bacteria are capable of surviving in the environment, there are visible differences. Selective media have been used to promote the growth of specific bacterial species while inhibiting others. Differential and selective media provide more information than a regular media. To distinguish a positive from a negative test result, positive and negative controls are necessary because results can vary. There is no correct species concept for bacteria. The most widely accepted concept groups species “based on overall genomic similarity and sharing of phenotypes deemed ecologically important” (Vos, 2011). This concept is different from the biological species concept used for eukaryotes. The biological species concept defines a species as a group of organisms within a population capable of interbreeding and producing viable offspring in nature. Species of bacteria do not undergo sexual reproduction, which makes the biological species concept inadequate for defining a species of bacteria. Another aspect of bacteria that makes defining a species concept difficult is the ability of prokaryotes to perform horizontal gene transfer..