The transport of Mycobacterium avium subsp. paratuberculosis through saturated aquifer materials.

AIMS To investigate the processes controlling the transport of Mycobacterium avium subsp. paratuberculosis (Map) through aquifer materials. METHODS AND RESULTS We measured two important surface characteristics known to affect bacterial attachment to sediment surfaces: surface charge and hydrophobicity. We then measured the transport of Map through laboratory columns packed with aquifer sand with varying ionic strength solutions and sediment surface charge. We found that Map has a strong negative charge and is highly hydrophobic and that the transport of Map through positively charged Fe-coated sands was reduced compared with transport through negatively charged clean quartz sand, although Map transport for all treatments was low compared with the transport behaviour reported in the literature for other bacteria. CONCLUSIONS Our results suggest that the potential for groundwater contamination by Map is low; however, the organism may remain bound to the soil near the surface where it can be ingested by grazing animals or be released during run off events. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first study looking at the surface characteristics and transport behaviour of Map through aquifer materials and therefore provides important information for understanding the movement of Map in the environment.