Project description:Members of the bacterial phylum Spirochaetes are primarily studied for their commensal and pathogenic roles in animal hosts. However, Spirochaetes are also frequently detected in anoxic hydrocarbon-contaminated environments but their ecological role in such ecosystems has so far remained unclear. Here we provide a functional trait to these frequently detected organisms with an example of a sulfate-reducing, naphthalene-degrading enrichment culture consisting of a sulfate-reducing deltaproteobacterium Desulfobacterium naphthalenivorans and a novel spirochete Rectinema cohabitans. Using a combination of genomic, proteomic, and physiological studies we show that R. cohabitans grows by fermentation of organic compounds derived from biomass from dead cells (necromass). It recycles the derived electrons in the form of H2 to the sulfate-reducing D. naphthalenivorans, thereby supporting naphthalene degradation and forming a simple microbial loop. We provide metagenomic evidence that equivalent associations between Spirochaetes and hydrocarbon-degrading microorganisms are of general importance in hydrocarbon- and organohalide-contaminated ecosystems. We propose that environmental Spirochaetes form a critical component of a microbial loop central to nutrient cycling in subsurface environments. This emphasizes the importance of necromass and H2-cycling in highly toxic contaminated subsurface habitats such as hydrocarbon-polluted aquifers.
Project description:We report the application of a high-throughput technique, RNA-seq, to study the transcriptomic response of P. putida KT2440 and DOT-T1E in the presence of toluene with the aim to study in more detail the mechanisms involved in toluene response in a toluene-sensitive and a toluene-tolerant strains.
Project description:Pseudomonas putida S12 is an inherently solvent-tolerant strain and constitutes a promising platform for biotechnology applications in whole-cell biocatalysis of aromatic compounds. The genome of P. putida S12 consists of a 5.8 Mbp chromosome and a 580 kbp megaplasmid pTTS12. pTTS12 encodes several genes which enable the tolerance to various stress conditions, including the main solvent efflux pump SrpABC. Removal (curing) of megaplasmid pTTS12 and subsequent loss of solvent efflux pump SrpABC caused a significant reduction in solvent tolerance of the resulting strain. In this study, we succeeded in restoring solvent tolerance in the megaplasmid-cured P. putida S12 using adaptive laboratory evolution (ALE) and molecular analysis to investigate the intrinsic solvent tolerance of P. putida S12. RNA-seq was performed to study the global transcriptomic response of the solvent-adapted plasmid-cured P. putida S12 in the presence of toluene. This analysis revealed the downregulation of ATP synthase, flagella and other RND efflux pumps, which indicates the importance of maintaining proton motive force during solvent stress.
Project description:High Arctic soils have low nutrient availability, low moisture content and very low temperatures and, as such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the microbiology involved in this process is likely to be crucial to understand and optimize the factors most influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments, located at Alert (ex situ approach) and Eureka (in situ approach), in the Canadian high Arctic. Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of bacteria found in cold environments and hydrocarbon degradation genes as well as reverse-transcriptase real-time PCR targeting key functional genes. Results indicated a large difference between sampling sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases and polyaromatic hydrocarbon ring-hydroxylating-dioxygenases were observed one month after the bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year). Such discrepancies are likely caused by differences in bioremediation treatments (i.e. ex situ vs. in situ), weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring of polar bacteria and their associated functions during bioremediation. 38 soil samples from two high arctic locations that were contaminated-treated, contaminated or not contaminated followed for up to 4 years
Project description:High Arctic soils have low nutrient availability, low moisture content and very low temperatures and, as such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the microbiology involved in this process is likely to be crucial to understand and optimize the factors most influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments, located at Alert (ex situ approach) and Eureka (in situ approach), in the Canadian high Arctic. Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of bacteria found in cold environments and hydrocarbon degradation genes as well as reverse-transcriptase real-time PCR targeting key functional genes. Results indicated a large difference between sampling sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases and polyaromatic hydrocarbon ring-hydroxylating-dioxygenases were observed one month after the bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year). Such discrepancies are likely caused by differences in bioremediation treatments (i.e. ex situ vs. in situ), weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring of polar bacteria and their associated functions during bioremediation. 38 soil samples from two high arctic locations that were contaminated-treated, contaminated or not contaminated followed for up to 4 years
Project description:Coxiella burnetii is an intracellular pathogen that causes Q fever, a zoonotic disease found worldwide. In humans, the bacterium is responsible for an acute and chronic disease. It is transmitted to humans by the inhalation of aerosols or contaminated dust containing bacteria from infected livestock. Recently C. burnetii re-emerged in Europe making considerable economic impact in farming industry and even causing multiple human cases. Antibiotic resistance represents a global public health problem; moreover, there are few reports about doxycycline resistance in C. burnetii. Understanding drug application consequences in tolerant bacterial strains is indispensable for the effective therapy. Herein, we report changes in proteome of C. burnetii challenged by antibiotic stress, highlighting polypeptides likely involved in the detoxification of doxycycline. These data were corroborated by gene expression analysis. Based on the identities of differentially abundant proteins we suggest that homeostasis of bacterial surface, oxidative stress defense and balanced carbon metabolism are key processes to survive doxycycline treatment.