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Environ Sci Technol. 2018 Oct 2;52(19):11049-11059. doi: 10.1021/acs.est.8b01066. Epub 2018 Sep 14.

Seasonal Gene Expression and the Ecophysiological Implications of Toxic Microcystis aeruginosa Blooms in Lake Taihu.

Author information

1
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China.
2
Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States.
3
Department of Chemistry , SUNY College of Environmental Science and Forestry , Syracuse , New York 13210 , United States.
4
Institute of Marine Sciences , The University of North Carolina at Chapel Hill , Morehead City , North Carolina 28557 , United States.
5
College of Environment , Hohai University , Nanjing , Jiangsu 210098 , China.

Abstract

Harmful cyanobacterial blooms represent an increasing threat to freshwater resources globally. Despite increased research, the physiological basis of how the dominant bloom-forming cyanobacteria, Microcystis spp., proliferate and then maintain high population densities through changing environmental conditions is poorly understood. In this study, we examined the transcriptional profiles of the microbial community in Lake Taihu, China at 9 stations sampled monthly from June to October in 2014. To target Microcystis populations, we collected metatranscriptomic data and mapped reads to the M. aeruginosa NIES 843 genome. Our results revealed significant temporal gene expression patterns, with many genes separating into either early or late bloom clusters. About one-third of genes observed from M. aeruginosa were differentially expressed between these two clusters. Conductivity and nutrient availability appeared to be the environmental factors most strongly associated with these temporal gene expression shifts. Compared with the early bloom season (June and July), genes involved in N and P transport, energy metabolism, translation, and amino acid biosynthesis were down-regulated during the later season (August to October). In parallel, genes involved in regulatory functions as well as transposases and the production of microcystin and extracellular polysaccharides were up-regulated in the later season. Our observation indicates an eco-physiological shift occurs within the Microcystis spp. transcriptome as cells move from the rapid growth of early summer to bloom maintenance in late summer and autumn.

PMID:
30168717
DOI:
10.1021/acs.est.8b01066

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