Improved biovar test for Ralstonia solanacearum.
Race 3, biovar 2 strains of Ralstonia solanacearum are quarantined pathogens in Europe and Canada and Select Agent pathogens in the United States. The biovar classification of R. solanacearum strains is based on their biochemical abilities to utilize a carbohydrate panel. The standard biovar test uses bromothymol blue as a pH indicator in 15 ml culture tubes containing 3 to 5 ml of test media, and takes weeks to complete at 24 or 28 °C. We improved the biovar test by using phenol red as a pH indicator that changes color at a higher pH when a carbohydrate is utilized. We also conducted the test at 32 °C in 0.2 ml of 8-tube strips that reduced the medium needed by at least 20 fold. Using the improved test, biovars of R. solanacearum strains can be determined in 4 days when a panel of seven carbohydrates is used including glucose, trehalose, mannitol, sorbitol, dulcitol, maltose and cellobiose. To differentiate biovars 1, 2, 3 and 4, the test can be further simplified and completed in 3 days using a panel of four carbohydrates containing glucose, trehalose, maltose and dulcitol, significantly saving money, space and time.
Floral and Nursery Plants Research Unit, United States National Arboretum, U.S. Dept. of Agriculture-Agricultural Research Service, Beltsville, MD 20705, USA. qi.huang@ars.usda.gov
Qi
Q
Huang
Xuerui
X
Yan
Jaw-Fen
JF
Wang
D015373:Bacterial Typing Techniques / Q000379:methods*; D050260:Carbohydrate Metabolism; D006863:Hydrogen-Ion Concentration; D010637:Phenolsulfonphthalein / Q000737:chemistry; D043368:Ralstonia solanacearum / Q000145:classification* / Q000378:metabolism; D013997:Time Factors
D010637:Phenolsulfonphthalein