Alcanivorax borkumensis isolate:ABS183 Genome sequencing and assembly

Formation of anhydrite crystals may preserve microbial cells and organic matter. In deep-sea sediment, the microbes in the anhydrite crystals after mild hydrothermal activities are markers of the past environment and can probably serve as nutrient reservoir. In this study, this hypothesis was examined by analyzing a metagenome in anhydrite crystals from a hydrothermal and hypersaline sediment core sampled at the Atlantis II Deep of the Red Sea. The 16S/18S rRNA genes in the metagenome were affiliated with Bacteria, Archaea, Fungi and even Arthropoda. The dominant species was alkane-degrading Alkanivorax bacterium, and its draft genome was separated from the metagenome of the anhydrite sample but not from that of the adjacent sediment. Phylogenetic relationship with known species and fluorescent microscope showed that the dominant bacterium in the crystals was a new strain of Alcanivorax borkumensis. The draft genome contains all the functional genes for alkane utilization and reduction of nitrogen oxides. Moreover, there are aromatic degradation pathways in the metagenomes of anhydrites and control sediment, which are mostly derived from Ochrobactrum sp. Estimated age of the anhydrite layer was between 750-770 years, which corresponds to the time of the hydrothermal eruption to the benthic floor and subsurface sediment. The presence of Alkanivorax and Ochrobactrum bacteria and identification of oil degradation genes in the anhydrites indicate the past oil-spilling benthic environment in the Atlantis II basin of the Red Sea. Moreover, increase of organic carbons in the anhydrite layers, compared with approximate layers, is also probably due to the trapped microbes, suggesting that the dissolution of the crystals may bolster the growth of microbial inhabitants.