Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Lak Si, Bangkok, Thailand.
Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.
Appl Microbiol Biotechnol. 2018 Jul;102(14):6235-6246. doi: 10.1007/s00253-018-9079-1. Epub 2018 May 21.
Enterococcus faecalis bacteria have been recently reported for their ability to host bacteriophages that are specifically from human sewage, suggesting their application to track human fecal contamination in water resources. However, little is known about the survivability of sewage-specific enterococcal bacteriophages in various water matrices under ambient and storage conditions. In this study, bacteriophages that were derived from the Thailand-isolated E. faecalis strains AIM06 and SR14 exhibited morphologies consistent with the Siphoviridae, Podoviridae, and Myoviridae families. Four representative bacteriophages were separately spiked into environmental water samples (n = 7) comprising freshwater and seawater with low- and high-pollution (LF, HF, LS, and HS, respectively) levels, defined according to Thailand Water Quality Standards. All bacteriophages decayed fastest in HS or HF samples at 30 °C, reaching a 5-log reduction in 2.2 to 9.8 days, and slowest in LS samples, requiring 8.8 to 23.5 days. The decay rates were 5 to 53 times lower at a storage temperature of 5 °C. HF samples could be stored for as little as 2.5 days to prevent the decay of 50% of the phages. Myoviridae phages decayed faster than Siphoviridae phages and Podoviridae phages in most water matrices at 30 °C. Moreover, the decay rates were 1.8 to 92 times slower in filtered samples, emphasizing a strong role for water constituents, i.e., suspended solids and natural microorganisms, in phage persistence. This study emphasized that differential enterococcal bacteriophage persistence should be considered when planning the monitoring and interpreting of fecal sources by microbial source tracking.
最近有报道称，粪肠球菌能够携带来自人类污水的噬菌体，这表明它们可用于追踪水资源中的人类粪便污染。然而，对于在环境和储存条件下，各种水体基质中特定于污水的肠球菌噬菌体的生存能力，人们知之甚少。在这项研究中，源自泰国分离的粪肠球菌菌株 AIM06 和 SR14 的噬菌体表现出与长尾噬菌体科、短尾噬菌体科和肌尾噬菌体科一致的形态。将四个代表性噬菌体分别添加到环境水样中（n=7），水样包括低污染和高污染的淡水和海水（LF、HF、LS 和 HS，分别根据泰国水质标准定义）。所有噬菌体在 30°C 下在 HS 或 HF 样品中降解最快，在 2.2 至 9.8 天内达到 5 个对数减少，在 LS 样品中降解最慢，需要 8.8 至 23.5 天。在 5°C 的储存温度下，衰减率降低了 5 至 53 倍。HF 样品的储存时间可以短至 2.5 天，以防止 50%的噬菌体衰减。在 30°C 下，大多数水体基质中肌尾噬菌体的衰减速度快于长尾噬菌体和短尾噬菌体。此外，在过滤样品中的衰减速度慢 1.8 至 92 倍，这强调了水成分（即悬浮固体和天然微生物）在噬菌体存活中的重要作用。本研究强调，在规划微生物源追踪监测和解释粪便来源时，应考虑不同的肠球菌噬菌体的持久性。
