Melioidosis is an emerging infectious disease of humans and animals in the 
tropics caused by the soil bacterium Burkholderia pseudomallei. Despite high 
fatality rates, the ecology of B.pseudomallei remains unclear. We used a 
combination of field and laboratory studies to investigate B.pseudomallei 
colonization of native and exotic grasses in northern Australia. Multivariable 
and spatial analyses were performed to determine significant predictors for 
B.pseudomallei occurrence in plants and soil collected longitudinally from field 
sites. In plant inoculation experiments, the impact of B.pseudomallei upon these 
grasses was studied and the bacterial load semi-quantified. Fluorescence in situ 
hybridization and confocal laser scanning microscopy were performed to localize 
the bacteria in plants. Burkholderia pseudomallei was found to inhabit not only 
the rhizosphere and roots but also aerial parts of specific grasses. This raises 
questions about the potential spread of B.pseudomallei by grazing animals whose 
droppings were found to be positive for these bacteria. In particular, 
B.pseudomallei readily colonized exotic grasses introduced to Australia for 
pasture. The ongoing spread of these introduced grasses creates new habitats 
suitable for B.pseudomallei survival and may be an important factor in the 
evolving epidemiology of melioidosis seen both in northern Australia and 
elsewhere globally.