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

This project was a continuation of ASAC project 870 (ASAC_870).The aim of the project is to assess the possible routes for the carriage of microorganisms by humans to Antarctic soil habitats. Such pathways include footwear, vehicle treads and washings of root vegetables. These have been examined and measures have already been implemented to minimise further risk from these sources. A further aim was to determine the likelihood of foreign microorganisms successfully competing with indigenous terrestrial antarctic microorganisms; this has proved more difficult to ascertain under simulated antarctic conditions. Work is continuing on this aspect.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.

本项目是ASAC项目870（ASAC_870）的延续。

本项目旨在评估人类将微生物携带至南极土壤生境的潜在途径，此类途径包括鞋类、车辆轮胎花纹以及根菜清洗水。已对这些途径展开调查，并已实施措施以降低此类来源带来的后续风险。另一目标是确定外来微生物与南极本土陆生微生物成功竞争的可能性；在模拟南极条件下，这一目标的验证难度更大，相关工作仍在进行中。

已评估探险队员靴子上的微生物污染物对南极野生动物生境构成的风险，结果发现：使用2% Virkon或3%氯漂白剂的现有步行消毒流程无法杀灭细菌孢子，但可杀灭大肠菌群。靴子花纹中的残留黏土会加剧孢子在消毒溶液中存活的问题。建议在进入南极水域前彻底刷洗靴子以去除残留土壤或黏土，且在南极境内地理隔离区域间移动时，需根据需要再次刷洗。若要使芽孢杆菌孢子数量减少3个对数级，需将其在2.0% Virkon中浸泡4小时，或在3%氯漂白剂中浸泡11分钟。

结果：
获得以下 Decimal Reduction Times（DRTs）：
枯草芽孢杆菌（B. subtilis）：在2% Virkon中为80分钟和84分钟，在3%氯漂白剂中为3.6分钟。
多黏芽孢杆菌（B. polymyxa）：在2% Virkon中为32分钟，在3%氯漂白剂中为3.0分钟。
大肠杆菌（E. coli）的营养细胞在Virkon和3%氯漂白剂中均快速死亡，其DRTs小于18秒（即所述方法的检测下限）。