Byappanahalli Muruleedhara N, Przybyla-Kelly Katarzyna, Shively Dawn A, Whitman Richard L
U.S. Geological Survey, Great Lakes Science Center, Lake Michigan Ecological Research Station, 1100 Mineral Springs Road, Porter, Indiana 46304, USA.
Environ Sci Technol. 2008 Nov 1;42(21):8014-20. doi: 10.1021/es800481p.
The enterococcal surface protein (esp) gene found in Enterococcus faecalis and E. faecium has recently been explored as a marker of sewage pollution in recreational waters but its occurrence and distribution in environmental enterococci has not been well-documented. If the esp gene is found in environmental samples, there are potential implications for microbial source tracking applications. In the current study, a total of 452 samples (lake water, 100; stream water, 129; nearshore sand, 96; and backshore sand, 71; Cladophora sp. (Chlorophyta), 41; and periphyton (mostly Bacillariophyceae), 15) collected from the coastal watersheds of southern Lake Michigan were selectively cultured for enterococci and then analyzed for the esp gene by PCR, targeting E. faecalis/ E. faecium (esp(fs/fm)) and E. faecium (esp(fm)). Overall relative frequencies for esp(fs/fm) and esp(fm) were 27.4 and 5.1%. Respective percent frequency for the esp(fs/fm) and esp(fm) was 36 and 14% in lake water, 38.8 and 2.3% in stream water, 24 and 6.3% in nearshore sand; 0% in backshore sand; 24.4 and 0% in Cladophora sp.; and 33.3 and 0% in periphyton. The overall occurrence of both esp(fs/fm) and esp(fm) was significantly related (chi2 = 49, P < 0.0001). Post-rain incidence of esp(fs/fm) increased in lake and stream water and nearshore sand. Further, E. coli and enterococci cell densities were significant predictors for esp(fs/fm) occurrence in post-rain lake water, but esp(fm) was not F+ coliphage densities were not significant predictors for esp(fm) or esp(fs/fm) gene incidence. In summary, the differential occurrence of the esp gene in the environment suggests that it is not limited to human fecal sources and thus may weaken its use as a reliable tool in discriminating contaminant sources (i.e., human vs. nonhuman).
粪肠球菌和屎肠球菌中发现的肠球菌表面蛋白（esp）基因最近被用作娱乐用水中污水污染的标志物，但该基因在环境肠球菌中的存在和分布情况尚未得到充分记录。如果在环境样本中发现esp基因，对于微生物源追踪应用可能具有潜在意义。在本研究中，从密歇根湖南部沿海流域采集了总共452个样本（湖水100个；溪水129个；近岸沙滩96个；后滨沙滩71个；刚毛藻（绿藻门）41个；周丛生物（主要是硅藻纲）15个），选择性培养肠球菌，然后通过PCR分析esp基因，分别针对粪肠球菌/屎肠球菌（esp(fs/fm)）和屎肠球菌（esp(fm)）。esp(fs/fm)和esp(fm)的总体相对频率分别为27.4%和5.1%。esp(fs/fm)和esp(fm)在湖水中的频率分别为36%和14%，溪水中为38.8%和2.3%，近岸沙滩中为24%和6.3%；后滨沙滩中为0%；刚毛藻中为24.4%和0%；周丛生物中为33.3%和0%。esp(fs/fm)和esp(fm)的总体出现情况显著相关（卡方 = 49，P < 0.0001）。雨后，esp(fs/fm)在湖水、溪水和近岸沙滩中的发生率增加。此外，大肠杆菌和肠球菌细胞密度是雨后湖水中esp(fs/fm)出现的显著预测指标，但esp(fm)不是。F+大肠杆菌噬菌体密度不是esp(fm)或esp(fs/fm)基因发生率的显著预测指标。总之，esp基因在环境中的差异出现表明它不限于人类粪便来源，因此可能会削弱其作为区分污染物来源（即人类与非人类）可靠工具的作用。
