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A New Semi-Selective Medium for Xanthomonas campestris pv. vitians, the Causal Agent of Bacterial Leaf Spot of Lettuce

February 2001 , Volume 85 , Number  2
Pages  131 - 136

V. Toussaint , MacDonald Campus of McGill University, 21 111 Lakeshore, Ste-Anne-de-Bellevue, Quebec, H9X 3V9, Canada ; C. E. Morris , Station de Pathologie Végétale, INRA d' Avignon, 84143, Monfavet, Cedex, France ; O. Carisse , Horticultural Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, St-Jean-sur-Richelieu, Quebec

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Accepted for publication 18 October 2000.

A semi-selective medium containing maltose, methyl green, and antibiotics (MMG) was developed for the isolation of Xanthomonas campestris pv. vitians. The semi-selective medium was evaluated based on plating efficiency of X. campestris pv. vitians in cell suspensions of pure cultures from leaves and soil. MMG medium allowed recovery of 5.7 to 30.6% of the X. campestris pv. vitians colonies recovered on nutrient agar and 0.1 to 8.4% of those recovered on 1/10-strength tryptic soy agar. MMG inhibited growth of most background bacteria and allowed reliable identification of X. campestris pv. vitians. The semi-selective medium contained (per liter) maltose (10 g), tryptone (5 g), K2HPO4 (3.5 g), KH2PO4 (2.75 g), trace elements (0.02 to 1.0 mg), methyl green (2 ml of a 1% aqueous solution), amoxicillin (32 mg), cephalothin (32 mg), cycloheximide (50 mg), and agar (15 g).

The American Phytopathological Society, 2001