First report of nodularin production by Nostochopsis sp. in a temperate eutrophic lake

Abstract

Benthic cyanobacteria are understudied in comparison to their planktonic counterparts. Consequently, our understanding of cyanotoxin production in benthic mats remains limited. We detected nodularin-R (NOD-R) in a population of Nostochopsis from Honeoye Lake (New York, United States). Identification as Nostochopsis was supported by morphological (see section 3.1 for a detailed description) and metagenomic analyses. The first metagenome assembled genome of Nostochopsis was drafted and estimated at 99.28 % complete. Cyanotoxin testing of Nostochopsis biomass showed production of NOD-R but not microcystins, anatoxins, or cylindrospermopsins. The complete nodularin synthetase cluster was confirmed in the Nostochopsis genome. To our knowledge, this is the first report of nodularin production, or any cyanotoxin production, by the benthic cyanobacteria Nostochopsis. This is the fourth genus of cyanobacteria reported to produce nodularins.

Keywords: Benthic cyanobacteria; Cyanotoxin; Freshwater; Hepatotoxin.