{'fraction_non_alphanumeric': 0.022706209453197405, 'fraction_numerical': 0.004402224281742354, 'mean_word_length': 5.31140350877193, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 1, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Microbial metagenomics of oil sands tailings ponds: small bugs, big data.

Modern molecular biology techniques, particularly new DNA sequencing methods, have opened our eyes to the fact that microorganisms live in an extraordinary range of natural environments, from desert soils and boiling hot springs to Antarctic ice, in ancient sea beds and under the surface of some rocks, inside leaves and in the human gut, among others. They also colonize manmade environments, such as the enormous oil sands tailings ponds in northeastern Alberta, Canada, that are commonly reported by the press as being toxic to all life. Although the tailings ponds may not be hospitable to higher organisms, all eight ponds that we have analyzed to date (comprising nearly 100 samples) harbour large, diverse, and complex communities of microbes (An et al. 2013; Penner and Foght 2010). In fact, we have found that microbes typically are present at about 1 million cells per millilitre of oil sands tailings, which scales to a total of about a sextillion (10 21 ) cells in the nearly 1 billion cubic metres of tailings currently retained in the Athabasca Oil Sands region. That approaches the estimated number of stars in the Universe! This begs the questions: Which microbes live in the tailings ponds? What are they doing there? Where did they come from? Are they important in situ, either impacting current tailings management or eventual reclamation strategies for the tailings ponds? To address such questions required substantial long-term funding to develop methods for analyzing large suites of refractory samples using nextgeneration DNA sequencing platforms. Genome Canada and corporate partners from the energy industry provided that support via “Metagenomics for Greener Production and Extraction of Hydrocarbon Energy” (the Hydrocarbon Metagenomics Project; www.hydrocarbonmetagenomics.com). The project investigated several aspects of fossil fuel production, including coal bed methane production and souring of conventional petroleum reservoirs, but this presentation focuses on oil sands. Media images of tailings ponds typically are aerial photographs showing murky water and floating bitumen. However, beneath that shallow water layer lies the vast bulk of the tailings: a thick gel-like suspension of mineral and organic waste generated by aqueous extraction of surface-mined oil sands ores. The ores primarily comprise sand, fine clay particles, and adherent bitumen (a viscous crude oil) that is extracted by using hot alkaline water plus hydrocarbon solvents such as naphtha, a refined product similar to kerosene and comprising hundreds of individual compounds. Most of the solvent (>99%) is recovered after extraction and re-used. The waste from the extraction process comprises a thin slurry of water, sand, clay, unextracted bitumen, and the unrecovered solvent: this is the material deposited and retained in the tailings ponds pending reclamation. The sand settles out of suspension rapidly and is collected for other purposes, but the suspended clays settle extremely slowly, requiring years or decades to achieve the consistency of toothpaste while the water (and some bitumen) rises to the pond surface for re-use. Meanwhile, microbes indigenous to the ores and the water that have survived the extraction process and those that are introduced through rainfall and blowing dust become established in the ponds. Because the vast majority of material in the tailings ponds is anaerobic, most of the microbes colonizing the ponds grow without access to oxygen (via sulfate reduction or methane generation) and some are even killed by exposure to air. What are these microbes doing in the ponds? The community composition and activity are dictated by the carbon sources available to support microbial growth. The predominant mass of organic material in the ponds is unextracted bitumen, but, because it is virtually nondegradable (like asphalt), it is not a significant carbon source for the microbes. Instead, the much smaller proportion of unrecovered solvent entrained in the fresh tailings is the major carbon input supporting growth of the indigenous microbes. More specifically, only certain components of the solvents are degraded under anaerobic conditions, typically only slowly over months or years.