Virulence and biodegradation potential of dynamic microbial communities associated with decaying Cladophora in Great Lakes.
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.
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.
Chan Lan
CL
Chun
Department of Chemistry, Valparaiso University, Valparaiso, IN 46383, United States.
Julie R
JR
Peller
Lake Michigan Ecological Research Station, U.S. Geological Survey, Chesterton, IN 46304, United States.
Dawn
D
Shively
Lake Michigan Ecological Research Station, U.S. Geological Survey, Chesterton, IN 46304, United States.
Muruleedhara N
MN
Byappanahalli
Lake Michigan Ecological Research Station, U.S. Geological Survey, Chesterton, IN 46304, United States.
Richard L
RL
Whitman
BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, United States.
Christopher
C
Staley
BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, United States.
Qian
Q
Zhang
BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, United States; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, United States.
Satoshi
S
Ishii
BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, United States; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, United States. Electronic address: sadowsky@umn.edu.
Michael J
MJ
Sadowsky
D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification / Q000472:pathogenicity*; D001673:Biodegradation, Environmental; D000460:Chlorophyta / Q000382:microbiology*; D017753:Ecosystem; D006114:Great Lakes Region; D060106:Lakes; D012336:RNA, Ribosomal, 16S; D014774:Virulence
D012336:RNA, Ribosomal, 16S
16S rRNA; Cladophora; Decomposition; Dynamics; Great Lake; Microbiota; Pathogens