oil-contaminated sediment Transcriptome. oil-contaminated sediment

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.

高浓度原油对蓝细菌（Cyanobacteria）具有毒性，但在适宜浓度范围内可促进蓝细菌聚集体的形成；然而，其确切诱导因素至今尚未明确阐明。本研究假设，随着氮素暴露浓度升高，会抑制受油污染沉积物中蓝细菌的积累。本研究通过整合16S核糖体RNA（rRNA）基因MiSeq测序与宏转录组学（metatranscriptome）分析，对蓝细菌水华（cyanobacterial blooms）展开了全面探究。在培养42天后的不同时间点，受油污染与未受油污染的沉积物中，蓝细菌序列数均随时间推移而增加。此外，添加氮营养可加速未污染实验微宇宙（microcosms）中的蓝细菌水华进程，但在暴露于原油的体系中，却会显著延缓水华现象的发生，并大幅降低蓝细菌的丰度。本研究结果明确表明，氮限制是受油污染实验微宇宙中蓝细菌丰度升高的关键驱动因素。此外，不同处理组间的水华蓝细菌丰度与组成存在显著差异，颤藻属（Oscillatoria）可能在受油污染的实验微宇宙中发挥着潜在且不可忽视的作用。