SX agar

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Contents

Purpose

Semiselective medium for isolation of starch-positive pathovars of Xanthomonas campestris (X. c. pvs. campestris, begoniae, fragaria, and corylina) from soil or plant tissues. Also useful for direct plating of contaminated seeds.

Ingredients

Ingredient 1 L 500 ml
Distilled water 1000 ml 500 ml
Soluble potato starch 10 g 5 g
Beef extract 1 g 0.5 g
Ammonium chloride 5 g 2.5 g
K2 HPO41 2 g 1 g
Agar 15 g 7.5 g
Methyl violet 2B (1% solution in 20% ethanol) 1 ml 0.5 ml
Methyl green (1% solution) 2 ml 1 ml
Cycloheximide (optional)* 0.25 g 0.125 g

Instructions

Notes

  • The medium should be violet in color when melted. Fahy (Plant Bacterial Diseases) incorrectly lists the wrong potassium salt, which results in a blue slush medium. It is also incorrect in the original paper1. The above, K2HPO4 is correct.


  • Cycloheximide can be added to inhibit fungi from growing on the medium.

References

  • Schaad, N. W., Jones, J. B. and Chun, W. 2001. Laboratory guide for the identification of plant pathogenic bacteria, 3rd edition. The American Phytopathological Society, St. Paul, MN. 373pp.

Contributed by

From the Culture Media for Plant Pathogenic Fungi and Bacteria, University of Massachusetts: Contributed by Robert L. Wick

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