Diversity and abundance of planctomycete populations associated with an algal bloom in a eutrophic lake

Abstract The planctomycete bacterial populations associated with an algal bloom occurring in a eutrophic lake (LaBonte Lake, Wyoming) were characterized by quantitative PCR and high-throughput sequencing of 16S rRNA genes. 16S rRNA sequencing was performed on samples recovered from different habitats of the littoral zone of the lake, including sediment, water, and floating algal mats. Sampling was performed both in May prior to the bloom development and in June during a bloom event. Planctomycete relative abundance, as measured by quantitative PCR, was higher in May compared to June. Within the 9,488-planctomycete sequences recovered in this study, sequences related to nine planctomycete genera were identified. Planctomycete diversity was highest in the sediment followed by algal mat and lowest in the water samples. Sequences related to the genus Rhodopirellula were approximately six times more abundant in the algal mat compared to the sediment or water. A minority of the sequences were shared between different habitats and only 2% of the planctomycete sequences were found to be cosmopolitan throughout the lake. These results suggest that planctomycete bacteria in LaBonte Lake show both temporal and spatial differences in diversity and abundance, with specific lineages related to the Rhodopirellula being enriched in association with the algal mat.