CSIRO Land and Water, Ecosciences Precinct, 41 Boggo Road, QLD, Australia.
CSIRO Land and Water, Ecosciences Precinct, 41 Boggo Road, QLD, Australia.
Sci Total Environ. 2021 Jan 10;751:141475. doi: 10.1016/j.scitotenv.2020.141475. Epub 2020 Aug 9.
Enteric pathogens can be present in drinking water catchments due to several point and non-point sources of faecal contamination. Pathogen and contaminant signatures will decay due to environmental stresses, such as temperature, Ultra Violet (UV) radiation, salinity, and predation. In this study, we determined the decay of the culturable faecal indicator bacterium (FIB) Escherichia coli (E. coli), two sewage-associated marker genes (Bacteroides HF183 and crAssphage CPQ_056), and enteric pathogens (Campylobacter spp., human adenovirus 40/41, and Cryptosporidium parvum) in two freshwater laboratory microcosms using culture-based, quantitative PCR (qPCR) and vital dye (determine the fraction of viable Cryptosporidium oocysts) assays. Freshwater samples from the Lake Wappa and Lake Wivenhoe (Australia) were seeded with untreated sewage and C. parvum oocysts, and their declining concentrations were measured over a 28-day period. Moreover, 16S rRNA amplicon sequencing was also undertaken to determine the change/shift in sewage-associated bacterial communities using SourceTracker. Overall, culturable E. coli and the HF183 marker gene decayed significantly (p < 0.05) faster than did the qPCR measured enteric pathogens suggesting that the absence of culturable FIB or qPCR HF183 in water samples may not indicate the absence of pathogens. The decay of crAssphage was similar to that of HAdV 40/41 and other pathogens tested, suggesting crAssphage may be a better surrogate for enteric viruses in sub-tropical catchment waters. The decay rates were greater at 25 °C compared to 15 °C, suggesting that FIB and pathogens persist longer in the winter season compared to summer. Overall decay rates of the tested microorganisms in this microcosm study suggest that sub-tropical conditions, especially temperature, have a negative impact on the persistence of tested microorganisms. Sewage-associated bacterial communities also showed similar patterns. Based on the results, which showed differences in simulated summer and winter temperatures for pathogen decay, corresponding management options and treatment need to be adjusted accordingly to minimize human health risks effectively.
肠病原体可通过多种点源和非点源粪便污染而存在于饮用水集水区中。由于环境压力（如温度、紫外线辐射、盐度和捕食），病原体和污染物特征会衰减。在这项研究中，我们使用基于培养的定量 PCR（qPCR）和活染料（确定活的隐孢子虫卵囊的分数）测定了两个淡水实验室微宇宙中可培养粪便指示菌（大肠杆菌）、两个与污水相关的标记基因（双歧杆菌 HF183 和 crAssphage CPQ_056）以及肠病原体（弯曲杆菌属 spp.、人腺病毒 40/41 和微小隐孢子虫）的衰减。来自澳大利亚 Wappa 湖和 Wivenhoe 湖的淡水样本用未经处理的污水和微小隐孢子虫卵囊接种，并在 28 天内测量其浓度下降情况。此外，还进行了 16S rRNA 扩增子测序，使用 SourceTracker 确定与污水相关的细菌群落的变化/转移。总体而言，可培养的大肠杆菌和 HF183 标记基因的衰减速度明显快于 qPCR 测量的肠病原体（p < 0.05），这表明水样中可培养 FIB 或 qPCR HF183 的缺失可能并不表示病原体的不存在。crAssphage 的衰减与 HAdV 40/41 和其他测试病原体相似，这表明 crAssphage 可能是亚热带集水区水中肠病毒的更好替代物。在 25°C 下的衰减率大于 15°C，这表明与夏季相比，冬季 FIB 和病原体在更长时间内持续存在。本微宇宙研究中测试微生物的总体衰减率表明，亚热带条件，特别是温度，对测试微生物的持久性有负面影响。与污水相关的细菌群落也显示出类似的模式。根据结果显示，在模拟夏季和冬季温度下病原体衰减存在差异，需要相应地调整相应的管理选项和处理措施，以有效降低人类健康风险。
