Department of Civil Engineering, University of Minnesota Duluth, Duluth, MN 55812, United States; Natural Resources Research Institute, University of Minnesota Duluth, Duluth, MN 55812, United States.
Department of Chemistry, Valparaiso University, Valparaiso, IN 46383, United States.
Sci Total Environ. 2017 Jan 1;574:872-880. doi: 10.1016/j.scitotenv.2016.09.107. Epub 2016 Oct 14.
Cladophora mats that accumulate and decompose along shorelines of the Great Lakes create potential threats to the health of humans and wildlife. The decaying algae create a low oxygen and redox potential environment favoring growth and persistence of anaerobic microbial populations, including Clostridium botulinum, the causal agent of botulism in humans, birds, and other wildlife. In addition to the diverse population of microbes, a dynamic chemical environment is generated, which involves production of numerous organic and inorganic substances, many of which are believed to be toxic to the sand and aquatic biotic communities. In this study, we used 16S-rDNA-based-amplicon sequencing and microfluidic-based quantitative PCR approaches to characterize the bacterial community structure and the abundances of human pathogens associated with Cladophora at different stages (up to 90days) of algal decay in laboratory microcosms. Oxygen levels were largely depleted after a few hours of incubation. As Cladophora decayed, the algal microbial biodiversity decreased within 24h, and the mat transitioned from an aerobic to anaerobic environment. There were increasing abundances of enteric and pathogenic bacteria during decomposition of Cladophora, including Acinetobacter, Enterobacter, Kluyvera, Cedecea, and others. In contrast, there were no or very few sequences (<0.07%) assigned to such groups in fresh Cladophora samples. Principal coordinate analysis indicated that the bacterial community structure was dynamic and changed significantly with decay time. Knowledge of microbial communities and chemical composition of decaying algal mats is critical to our further understanding of the role that Cladophora plays in a beach ecosystem's structure and function, including the algal role in trophic interactions. Based on these findings, public and environmental health concerns should be considered when decaying Cladophora mats accumulate Great Lakes shorelines.
沿大湖湖岸堆积和分解的石莼藻垫给人类和野生动物的健康带来了潜在威胁。藻类的腐烂会产生低氧和氧化还原电位环境，有利于厌氧微生物种群的生长和持续存在，包括人类肉毒梭菌、鸟类和其他野生动物肉毒中毒的病原体。除了微生物的多样化种群外，还会产生动态的化学环境，涉及到许多有机和无机物质的产生，其中许多物质被认为对沙质和水生生物群落有毒。在这项研究中，我们使用基于 16S-rDNA 的扩增子测序和基于微流控的定量 PCR 方法来描述细菌群落结构和与石莼在实验室微生境中不同分解阶段（长达 90 天）相关的人类病原体的丰度。在孵育几个小时后，氧气水平大部分被耗尽。随着石莼的腐烂，藻类微生物多样性在 24 小时内减少，藻垫从需氧环境转变为厌氧环境。在石莼分解过程中，肠道和致病性细菌的丰度增加，包括不动杆菌、肠杆菌、克氏杆菌、西地西菌等。相比之下，在新鲜的石莼样本中，没有或只有很少的序列（<0.07%）被分配到这些组中。主坐标分析表明，细菌群落结构是动态的，随着分解时间的变化而显著变化。了解腐烂藻垫中的微生物群落和化学成分对于我们进一步了解石莼在海滩生态系统结构和功能中的作用至关重要，包括藻类在营养相互作用中的作用。基于这些发现，当腐烂的石莼垫在大湖湖岸堆积时，应该考虑公共和环境健康问题。
