V-factor or nicotinamide adenine dinucleotide (NAD) is a coenzyme involved in redox reactions. Some bacteria
cannot produce NAD and need to get it from the substrate or grow as a satellite of a NAD-producing organism.
Satellitism can be demonstrated on an agar medium lacking the V-factor
by cross-inoculating the plate with a feeder strain (e.g. Staphylococcus or
Pseudomonas). The NAD-requiring strain will grow only in the vicinity of
the NAD-producing strain.
V-factor impregnated disks may be used instead of the feeder strain.
NAD is destroyed by autoclaving the medium.
The satellite phenomenon may be difficult to achieve in ordinary agar
plates because blood may contain various amounts of V-factor. For a
NAD-free medium autoclaving is required after adding the blood.
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
2. J. G.Holt et al., 1994.Begey’s manual of Determinative Bacteriology, 9-edition, Williams & Wilkins.
|Actinobacillus pleuropneumoniae dependent of
V factor (NAD)-producing Staphylococcus (line) and
CAMP positive reaction
(c) Costin Stoica