Biogeographic and population analyses of Thermotogales bacteria from hydrocarbon-rich environments

The Thermotogae bacteria are anaerobic bacteria thriving in many different anoxic environments. The majority of these bacteria are thermophiles, growing at temperatures up to 90°C. The hyperthermophilic Thermotoga are commonly found in hot oil reservoirs (e.g. the Troll oil reservoir in the North Sea) and marine hydrothermal vents, while the mesophilic Mesotoga are commonly found cooler oil reservoirs (e.g. the oil sands in Alberta) and waste water treatment facilities. We have genome sequences from isolates from both these lineages and observe very different phylogeographic patterns for these groups. The hyperthermophiles show a globally connected population, with distinct subsurface and surface subpopulations. However, we also see high levels of gene flow between the sub-populations. The mesophilic Mesotoga show a very different phylogeographic pattern, with three distinct lineages that show very little gene flow between them. This suggests they have been evolving independently for a long time. One of these lineages shows evidence of a recent range expansion, with very similar genomes detected all over the world. We identified a gene suggested to be involved in survival in harsh environments that may have been important for their increased ability to spread. The two other lineages show restricted distribution, and one of them is only found in oil reservoirs in Alberta, suggesting it may have been isolated there since the oil-bearing sediments there formed. We are also investigating distribution of viruses and other mobile genetic elements in these bacteria, as well as their adaptation to growth at high and low temperatures. For the temperature experiments, we are using Kosmotoga olearia (from Troll) as a model, as it can grow from ~25°C - 77°C. Transcriptomic studies show that a large proportion of its genes respond to changes in temperature, and that it my have different ecological roles at different temperatures. We also find that many of the key-genes for low temperature growth have been acquired form other organisms throught lateral gene transfer. Finally, we have started comparing the patterns observed among the Thermotogae to other reservoir dwelling microbes as well as the pathogen Bacillus anthracis.

13.5.2011: Nytt prosjektsammendrag: We propose to obtain genome and metagenome sequences from Thermotogales isolates and enrichment cultures, from hydrocarbon-rich environments (e.g. oil reservoirs). We will also obtain metagenomic data from environmetal samples with low diversity and/or high numbers of Thermotogales bacteria. The sequences will be used to investigate the population structure and biogeography of these bacteria; e.g. level of migration and genetic exchange within and between geographical sites. We will also explore how oil-reservoir-Thermotogales bacteria are adapted to this environment through comparative genomic analyses as well as selective cultivation. The data generated will give us information on how these bacteria can interact gene tically over large geographic distances and how frequent such migrations between populations are, as well as help answer if Thermotogales populations in oil reservoirs are truly indigenous to oil fields or if they are introduced for instance during reserv oir development. By studying both thermophilic and mesophilic populations we will be able to assess how these different life styles affect their genomes and populations. Our findings will also further our understanding on what constitutes a prokaryotic sp ecies, one of the most contentious issues in microbiology. Finally, the data obtained here will have implications for biotechnology and oil industry. Microbes living in oil reservoirs can have both pernicious and beneficial effects on oil production. For instance, microbial biodegradation of oil has negative economic consequences (17, 69). Microbial enhanced oil recovery, in contrast, has the potential to offer cost-effective solutions (31). Current production technologies can recover 1/3 - ½ of the oil i n a reservoir; technologies that can help recover even parts of the remaining oil will have significant long-term impact. Thus, one long-term goal of this project is to help develop the basic science needed to understand the effects microbes have on oil r eservoirs through studying bacteria thought to be indigenous (or at least readily adaptable) to oil fields. We propose to obtain a minimum of 100 - 200 new Thermotogales strains mainly from hydrocarbon-rich environments, such as oil res ervoirs, as well as from mesophilic polluted sediments. The isolates will be used in MLST and genomic analyses to investigate the population structure and biogeography of these bacteria; e.g. level of migration and genetic exchange within and between geog raphical sites. We will also explore how oil-reservoir-Thermotogales bacteria are adapted to this environment by obtaining genes specific for such strains through subtractive hybridization. The data generated here will give us information on how these bac teria can interact genetically over large geographic distances and how frequent such migrations between populations are, as well as help answer if Thermotogales populations in oil reservoirs are truly indigenous to oil fields or if they are introduced e.g . during reservoir development. By studying both thermophilic and mesophilic populations we will be able to assess how these different life styles affect population structure. Our findings will also further our understanding on what constitutes a prokaryo tic species, one of the most contentious issues in microbiology. Finally, the data obtained here will have implications for biotechnology and oil industry. Microbes living in oil reservoirs can have both pernicious and beneficial effects on oil production . For instance, microbial biodegradation of oil has negative economic consequences. Microbial enhanced oil recovery, in contrast, has the potential to offer cost-effective solutions. Current production technologies can recover 1/3 - ½ of the oil in a rese rvoir; technologies that can help recover even parts of the remaining oil will have significant long-term impact. Thus, one long-term goal of this project is to help develop the basic science needed to understand the effects microbes have on oil reservoir s through studying bacteria thought to be indigenous to oil fields.