Xu Changyun, Salsali Hamidreza, Weese Scott, Warriner Keith
a Department of Food Science, University of Guelph, ON N1G 2W1, Canada.
b School of Engineering, University of Guelph, ON N1G 2W1, Canada.
Can J Microbiol. 2016 Jan;62(1):16-23. doi: 10.1139/cjm-2015-0511. Epub 2015 Oct 14.
There has been an increase in community-associated Clostridium difficile infections with biosolids derived from wastewater treatment being identified as one potential source. The current study evaluated the efficacy of thermophilic digestion in decreasing levels of C. difficile ribotype 078 associated with sewage sludge. Five isolates of C. difficile 078 were introduced (final density of 5 log CFU/g) into digested sludge and subjected to anaerobic digestion at mesophilic (36 or 42 °C) or thermophilic (55 °C) temperatures for up to 60 days. It was found that mesophilic digestion at 36 °C did not result in a significant reduction in C. difficile spore levels. In contrast, thermophilic sludge digestion reduced endospore levels at a rate of 0.19-2.68 log CFU/day, depending on the strain tested. The mechanism of lethality was indirect - by stimulating germination then inactivating the resultant vegetative cells. Acidification of sludge by adding acetic acid (6 g/L) inhibited the germination of spores regardless of the sludge digestion temperature. In conclusion, thermophilic digestion can be applied to reduce C. difficile in biosolids, thereby reducing the environmental burden of the enteric pathogen.
社区获得性艰难梭菌感染有所增加，源自废水处理的生物固体被确定为一个潜在来源。当前研究评估了嗜热消化法在降低与污水污泥相关的艰难梭菌核糖体分型078水平方面的效果。将5株艰难梭菌078菌株（最终密度为5 log CFU/g）引入消化后的污泥中，并在中温（36或42°C）或高温（55°C）下进行厌氧消化，长达60天。结果发现，36°C的中温消化并未导致艰难梭菌孢子水平显著降低。相比之下，嗜热污泥消化使芽孢水平以每天0.19 - 2.68 log CFU的速率降低，具体取决于所测试的菌株。致死机制是间接的——通过刺激芽孢萌发，然后使产生的营养细胞失活。添加乙酸（6 g/L）使污泥酸化，无论污泥消化温度如何，均会抑制孢子萌发。总之，嗜热消化法可用于减少生物固体中的艰难梭菌，从而减轻这种肠道病原体的环境负担。
