V-Factor Requirement
DESCRIPTION
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.

NOTES:
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.
REFERENCES:
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.
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Actinobacillus pleuropneumoniae (pinpoint
colonies) dependent of V factor (NAD) - producing
Staphylococcus aureus (yellow line)