Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.25.221044v1?rss=1 Authors: Rezaei Somee, M., Dastgheib, S. M. M., Shavandi, M., Ghanbari Maman, L., Kavousi, K., Amoozegar, M. A., Mehrshad, M. Abstract: Persian Gulf hosting ca. 48% of the world's oil reserves; has been chronically exposed to natural oil seepage. Oil spill events have been studied over the last decade; however, the influence of chronic oil exposure on the microbial community of the Persian Gulf has remained unknown. We performed genome-resolved comparative analyses of the water and sediment's prokaryotic community along the Gulf's pollution continuum (Strait of Hormuz, Asalouyeh and Khark Island). The continuous exposure to trace amounts of pollution has shifted the microbial profile toward the dominance of Oceanospirillales, Flavobacteriales, Alteromonadales, and Rhodobacterales in Asalouyeh and Khark samples. Intrinsic oil-degrading microbes present in low abundances in marine habitats; experience a bloom in response to oil pollution. Comparative analysis of the Persian Gulf samples with 106 oil-polluted marine samples reveals the pollutant's hydrocarbon content, exposure time and sediment depth as main determinants of microbial response to pollution. High aliphatic content enriches for Oceanospirillales, Alteromonadales and Pseudomonadales whereas, Alteromonadales, Cellvibrionales, Flavobacteriales and Rhodobacterales dominate polyaromatic polluted samples. In sediment samples, Deltaproteobacteria and Gammaproteobacteria had the highest abundance. In chronic exposure and oil spill events, the community composition converges towards higher dominance of oil-degrading constituents while promoting the division of labor for successful bioremediation. Copy rights belong to original authors. Visit the link for more info