Pseudomonas HiVeg™ Agar (For Fluorescein)

Principle and Interpretation

Pseudomonas HiVeg Agar (For Fluorescein) is prepared with the replacement of animal peptone by HiVeg peptone to avoid BSE/ TSE risks. Pseudomonas HiVeg Agar (For Fluorescein) is the modification of Pseudomonas Agar (For Fluorescein) which is based on the formula described by King et al (1) for the detection of fluorescein production, a water soluble, chloroform insoluble fluorescent pigment by Pseudomonas species (2). The medium enhances the elaboration of fluorescein by Pseudomonas and inhibits the pyocyanin formation. The fluorescein pigment diffuses from the colonies of Pseudomonas into the agar and shows yellow fluorescent colouration. Some Pseudomonas strains produce small amounts of pyocyanin resulting in a yellow-green colouration.

HiVeg hydrolysate and HiVeg peptone No.3 provide the essential nitrogenous nutrients, carbon, sulphur and trace elements for the growth of Pseudomonas. Glycerol acts as a source of energy and enhances pigment production. Dipotassium phosphate buffers the medium as well as increases the phosphorus content of the medium, thereby enhancing production of fluorescein pigment. Magnesium sulphate provides necessary cations for the activation of fluorescein production. Salt concentration exceeding 2% affects pigment production. UV illumination may be bactericidal, so make sure that there is good growth before placing culture under UV light (2). The formation of non pigmented colonies does not completely rule out a Pseudomonas aeruginosa isolate.