In regard to oxygen needs, all enterobacteria are they gram-stain and many are and look similar under a microscope. can be used to distinguish between closely related species.

In regar to oxygen needs, all enterobacteria are facultative anaerobes. They Gram stain negative,and are rod- shaped and look similar under a microscope. Biochemical, serological and molecular tests can be used to distinguish between closely related species.

Explanation:

The family Enterobacteriaceae is formed by 53 genera and over 170 species. There are 26 that have a medical importance as they are associated with infections in humans. An example of those are the genera Citrobacter, Enterobacter, Escherichia, Hafnia, Kliebsiella, Marganella, Plesiomonas shigelloides, Proteus, Providencia, Salmonella, Serratia, Shigella, Yersinia.

The enterobacteria are Gram negative (they are stained in red/pink dye), rod-shaped and non-sporing. They are facultative anaerobes, that means that they can survive in the presence of oxygen but they also can be adapted to live in an oxygen-free (anaerobic)environment. They can be found all around the world in humans, animals, soil, water and plants.

The identification methods that are used to distinguish this family from other bacteria are  the morphology of the colony, Gram staining, and biochemical tests.

To distinguish between closed species of eneterobacteria there are biochemical, serological and molecular tests. The biochemical test that is commonly used is the Lactose Fermentation test. On the other hand, a serological method is the serotyping that is based on the immuno-reactivity of antigens such as somatic (O) and flagellar (H). And for the molecular methods include the Multilocus Sequence Typing (MLST), Polymerase Chain Reaction (PCR), Multiple-locus Variable Number Tandem-Repeat Analysis (MVLA), Matrix Assisted Laser Desorption/Ionisation-Time of Flight (MALDI-TOF) Mass Spectometry, Pulsed Field Gel Electrophoresis (PFGE), Whole Genome Sequencing (WGS).