TY - JOUR
T1 - Secondary metabolite gene expression and interplay of bacterial functions in a tropical freshwater cyanobacterial bloom
AU - Penn, Kevin
AU - Wang, Jia
AU - Fernando, Samodha C.
AU - Thompson, Janelle R.
N1 - Funding Information:
This research was funded by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology’s Center for Environmental Sensing and Modeling (CENSAM) research program. The National Science Foundation Postdoctoral Research Fellowship in Biology under Grant No. DBI-1202865 supports KP. We also thank the MIT Center for Environmental Health Sciences (US National Institute of Environmental Health Sciences NIEHS Grant P30-ES002109) for core facility support and the MISTI-Hayashi fund for travel support. We thank Dr Peter Shanahan, MIT, Professor Lloyd Chua at NTU and Dr Hans Eikaas and others at the Public Utilities Board of Singapore for help in coordinating sampling, Professor Libusha Kelly for advice on bioinformatic analysis and members of the laboratory of Professor Karina Gin at the National University of Singapore for helpful discussions regarding harmful algal blooms in the Kranji Reservoir.
PY - 2014/9
Y1 - 2014/9
N2 - Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB.
AB - Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB.
KW - cyanobacteria
KW - metatranscriptomics
KW - microcystin
KW - microcystis
KW - toxins
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U2 - 10.1038/ismej.2014.27
DO - 10.1038/ismej.2014.27
M3 - Article
C2 - 24646695
AN - SCOPUS:84906943195
SN - 1751-7362
VL - 8
SP - 1866
EP - 1878
JO - ISME Journal
JF - ISME Journal
IS - 9
ER -