Assessment of the potential for microbial contamination of antarctic terrestrial habitats resulting from human activities (previously ASAC 870)

The danger posed by microbial contaminants on expeditioners' boots to antarctic wildlife habitats has been assessed, with the finding that bacterial spores would survive current walk-through disinfection procedures using 2% Virkon or 3%-chlorine bleach, although coliforms would not. The problem of spore-survival in sanitizing solutions is exacerbated by residual clay in boot treads. It is recommended that boots be scrubbed clean of residual soil or clay before entering antarctic waters, and again as necessary between geographically isolated areas within Antarctica.

Soaking for four hours in 2.0% Virkon or for 11 minutes in 3% chlorine bleach is needed for a 3-log reduction in Bacillus spore numbers. Results: The following Decimal Reduction Times (DRTs) were obtained: B. subtilis, 80 and 84 minutes in 2% Virkon , 3.6 min in 3%-chlorine bleach. B. polymyxa, 32 minutes in 2% Virkon , 3.0 min in 3%-chlorine bleach.

Vegetative cells of E. coli died very rapidly in both Virkon and 3%-chlorine bleach, with DRTs being less than 18 seconds, the limit of detection using the described method.