Gram-RodCat+Ox+

Oxidase Positive Gram Negative Rods
The three genera included in this section are Aeromonas, Alcaligenes, and'' Pseudomonas. The complete list of organisms are A. hydrophila, A. faecalis, P. fluorescens, P. aeruginosa, P. paucimobilis, and P. stutzeri''. Make sure to keep track of colony qualities for this group. Several of the organisms will produce pigments helpful, and sometimes necessary, to identification.

Tests
Required: Nitrate, PR Glucose, OF Glucose, Citrate, Thiogel

Helpful: TSI, OF Lactose

Key
1-A: Organism is PR Glucose positive and reduces Nitrate (NO3) to Nitrite (NO2)  [A red color will be produced when reagents are added to broth, but before zinc is added], also is Thiogel positive(gelatin has liquified) and has an A/A (completely yellow) result on TSI Aeromonas hydrophila

1-B: Organismis PR Glucose negative and is either Nitrate inert [requires zinc to turn red] or reduces to Nitrogen gas.[no red coloration at all, but has captured gas in the inverted tube] K/K (comlpetely red) reaction on TSI GO TO 2

2-A: Thiogel positive, Nitrate variable but most often reduces to Nitrogen gas GO TO 3

2-B: Thiogel negative, Nitrate inert GO TO 5

3-A: Citrate positive, still Nitrate variable GO TO 4

3-B: Citrate negative, Nitrate to Nitrogen gas Pseudomonas stutzeri

4-A: Pink pigment production, sometimes Nitrate inert, is not positive for OF Lactose, but can turn the media blue in the open tube (the tube no oil has been added to) Pseudomonas fluorescens

4-B: Green pigment production (will defuse and discolor media), Nitrate to Nitrogen gas reaction, no reaction in OF Lactose Pseudomonas aeruginosa

5-A: Organism is OF glucose inert Alcaligenes faecalis

5-B: Organism is OF glucose positive in the open tube (Glucose oxidation result) Pseudomonas paucimobilis