Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida, USA.
Appl Environ Microbiol. 2012 Sep;78(17):5973-82. doi: 10.1128/AEM.00603-12. Epub 2012 Jun 15.
Enterococci, recommended at the U.S. federal level for monitoring water quality at marine recreational beaches, have been found to reside and grow within beach sands. However, the environmental and ecological factors affecting enterococcal persistence remain poorly understood, making it difficult to determine levels of fecal pollution and assess human health risks. Here we document the presence of enterococci associated with beach sediment biofilms at eight south Florida recreational beaches. Enterococcal levels were highest in supratidal sands, where they displayed a nonlinear, unimodal relationship with extracellular polymeric secretions (EPS), the primary component of biofilms. Enterococcal levels peaked at intermediate levels of EPS, suggesting that biofilms may promote the survival of enterococci but also inhibit enterococci as the biofilm develops within beach sands. Analysis of bacterial community profiles determined by terminal restriction fragment length polymorphisms showed the bacterial communities of supratidal sediments to be significantly different from intertidal and subtidal communities; however, no differences were observed in bacterial community compositions associated with different EPS concentrations. Our results suggest that supratidal sands are a microbiologically unique environment favorable for the incorporation and persistence of enterococci within beach sediment biofilms.
肠球菌被推荐用于监测海洋休闲海滩水质的美国联邦水平,已被发现存在于海滩沙中并生长。然而,影响肠球菌持续存在的环境和生态因素仍了解甚少,这使得确定粪便污染水平和评估人类健康风险变得困难。在这里,我们记录了与佛罗里达州南部八个休闲海滩沉积物生物膜相关的肠球菌的存在。肠球菌水平在潮上带沙中最高,与细胞外聚合物分泌物(EPS)呈非线性单峰关系,EPS 是生物膜的主要成分。肠球菌水平在 EPS 的中间水平达到峰值,表明生物膜可能促进肠球菌的生存,但随着生物膜在海滩沙中发育,也会抑制肠球菌。通过末端限制性片段长度多态性分析确定的细菌群落图谱分析表明,潮上带沉积物的细菌群落与潮间带和潮下带群落显著不同;然而,与不同 EPS 浓度相关的细菌群落组成没有差异。我们的结果表明,潮上带砂是一个微生物独特的环境,有利于肠球菌在海滩沉积物生物膜中的掺入和持续存在。