oil-contaminated sediment Transcriptome

High concentrations of crude oil are toxic to cyanobacteria but can facilitate the emergence of cyanobacterial aggregation within an appropriate concentration range; however, the exact inducing factors have never been clearly elucidated. We hypothesized that increasing exposure to elevated concentrations of nitrogen would inhibit the accumulation of cyanobacteria in oil-contaminated sediments. An integrated MiSeq sequencing of 16S rRNA gene analysis along with metatranscriptome analyses was performed to achieve a comprehensive study of cyanobacterial blooms. The number of cyanobacterial sequences increased over time in both oil-contaminated and non-oil-contaminated sediments at different time points after 42 days of incubation. And, addition of nitrogen nutrients could accelerate cyanobacterial blooms in non-contaminated microcosms but significantly delay the bloom phenomenon and reduce the cyanobacterial abundance to a great degree when exposed to oil. Our results clearly illustrated that nitrogen limitation was a vital driver of the increased abundance of cyanobacteria in oil-contaminated microcosms. In addition, the abundance and compositions of blooming cyanobacteria varied significantly among the different treatment groups, and Oscillatoria may play a potential and non-negligible role in oil-contaminated microcosms.