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Flaxseed is high in ω-3 polyunsaturated fatty acids, fiber, and lignans known to lower cholesterol levels. However, its use for prevention or treatment of inflammatory bowel diseases has yielded mixed results, perhaps related to dietary interactions. In this study, we evaluated the impact of ground flaxseed supplementation on the severity of Citrobacter rodentium-induced colitis in the setting of either a high-fat (HF, ~36%kcal) or reduced-fat (RF, ~12%kcal) diet. After weaning, C57BL/6 mice ( n = 8–15/treatment) were fed ground flaxseed (7 g/100 g diet) with either HF (HF Flx) or RF (RF Flx) diets for 4 wk before infection with C. rodentium or sham gavage. Weight changes, mucosal inflammation, pathogen burden, gut microbiota composition, tissue polyunsaturated fatty acids, and cecal short-chain fatty acids were compared over a 14-day infection period. The RF diet protected against C. rodentium-induced colitis, whereas the RF Flx diet increased pathogen burden, exacerbated gut inflammation, and promoted gut dysbiosis. When compared with the RF diet, both HF and HF Flx diets resulted in more severe pathology in response to C. rodentium infection. Our findings demonstrate that although an RF diet protected against C. rodentium-induced colitis and associated gut dysbiosis in mice, beneficial effects were diminished with ground flaxseed supplementation. NEW & NOTEWORTHY Our results demonstrate a strong protective effect of a reduced-fat diet against intestinal inflammation, dysbiosis, and pathogen burden during Citrobacter rodentium-induced colitis. However, ground flaxseed supplementation in the setting of a reduced-fat diet exacerbated colitis despite higher levels of intestinal n-3 polyunsaturated fatty acids and cecal short-chain fatty acids.

The intestinal microbiota plays a key role in shaping the host immune system. Perturbation of gut microbial composition, termed dysbiosis, is associated with an increased susceptibility to intestinal pathogens and is a hallmark of a number of inflammatory, metabolic, and infectious diseases. The prospect of mining the commensal gut microbiota for bacterial strains that can impact immune function represents an attractive strategy to counteract dysbiosis and resulting disease. In this study, we show that selective enrichment of commensal gut lactobacilli protects against the murine pathogen Citrobacter rodentium, a well-characterized model of enteropathogenic and enterohemorrhagic Escherichia coli infection. The lactobacilli-enriched bacterial culture prevented the expansion of Gammaproteobacteria and Actinobacteria and was associated with improved indexes of epithelial barrier function (dextran flux), transmissible crypt hyperplasia, and tissue inflammatory cytokine levels. Moreover, cultivation of gut bacteria from Citrobacter rodentium-infected mice reveals the differential capacity of bacterial subsets to mobilize neutrophil oxidative burst and initiate the formation of weblike neutrophil extracellular traps. Our findings highlight the beneficial effects of a lactobacilli -enriched commensal gut microenvironment and, in the context of an intestinal barrier breach, the ability of neutrophils to immobilize both commensal and pathogenic bacteria.

Hibernia is Canada’s largest offshore oil platform. Produced water is the major waste byproduct discharged into the ocean. In order to evaluate different potential disposal methods, a comprehensive study was performed to determine the impact from the discharge. Microorganisms are typically the first organisms to respond to changes in their environment. The objectives were to characterize the microbial communities and the chemical composition in the produced water and to characterize changes in the seawater bacterial community around the platform. The results from chemical, physicochemical, and microbial analyses revealed that the discharge did not have a detectable effect on the surrounding seawater. The seawater bacterial community was relatively stable, spatially. Unique microorganisms like Thermoanaerobacter were found in the produced water. Thermoanaerobacter-specific q-PCR and nested-PCR primers were designed, and both methods demonstrated that Thermoanaerobacter was present in seawater up to 1000 m from the platform. These methods could be used to track the dispersion of produced water into the surrounding ocean.

There is currently limited scientific data to assess whether groundwater bacterial communities in fractured rock environments can degrade petroleum hydrocarbon plumes in cold regions. The former Colomac Mine is located in the Canadian Shield in the Northwest Territories (mean annual air temperature of -. 5°C) and is currently listed on the Federal Contaminated Sites inventory. Groundwater in fractured rock beneath the former fuel tank-farm at the mine site is contaminated by petroleum hydrocarbons. The objectives of this study were to investigate the bacterial community structure in the groundwater associated with hydrocarbon contamination, and to probe for potential anaerobic microbial processes involved in intrinsic bioremediation. Groundwater monitoring wells previously installed at the site were used to collect samples for chemical, isotopic and microbial analyses. Denaturing gradient gel electrophoresis (DGGE) analysis identified a relatively high bacterial diversity in the least contaminated locations, but as the hydrocarbon contamination increased, bacterial diversity decreased. Sequence analysis of the 16S rRNA gene demonstrated that the bacteria belonged to a wide range of genera, such as Pseudomonas, Thiobacillus, and Geobacter, all of which have been associated with the anaerobic degradation of hydrocarbons. Two putative nitrate-reducing genes were detected in samples with high nitrate reducing activity. Both chemical and microbiological results indicated the presence of microbial anaerobic processes by using nitrate, manganese(IV), ferric iron and sulfate as electron acceptors and suggest that these anaerobic processes play an important role in the biodegradation of dissolved petroleum hydrocarbons in the groundwater at the Colomac site. Our results also revealed that more than one biogeochemical process linked to hydrocarbon degradation could be present in a single borehole and these processes could vary spatially at this site., Erratum published in volume 89, page 48, May 2013. DOI: 10.1016/j.coldregions.2013.01.007

Produced water is one of the largest waste products routinely discharged into the ocean from offshore oil and gas platforms. This study analyzed bacterial communities and metals in the produced water, surrounding seawater, and sediment around the Thebaud platform. The bacterial community within the produced water was different from the seawater (SAB = 13.3), but the discharge had no detectable effect on the bacterial communities in the seawater (SAB > 97). In contrast, genomic analysis of sediments revealed that the bacterial community from 250 m was different (SAB = 70) from other locations further from the discharge, suggesting that the produced water had a detectable effect on the bacterial community in the sediment closest to the discharge. These near-field sediments contained elevated concentrations of manganese and iron that are associated with the produced water effluent. The results suggested that the discharge of produced water has influenced the bacterial community structure of sediments adjacent to the platform.

The focus of this study is to characterize the bacterial community structure present during stirred-tank bioleaching of a low-grade nickel sulphide ore at different temperatures (5 to 45 °C) and pH levels (3 and 5). This is a continuation of previous work, which was designed to assess the technical feasibility of applying elevated-pH bioleaching to this same ore from Manitoba, Canada. A combination of classical microbiological and molecular biological techniques has been used to identify and enumerate the members of the bacterial consortia over the course of the five-week experiments. DGGE analysis revealed the presence of at least 16 distinct 16S rRNA gene sequences, 14 of which are closely related to existing GenBank sequences. Two sequences were detected that are not closely related to existing GenBank sequences and may possibly be from novel species. Thirteen sequences are related to gene sequences of genera that have previously been detected in bioleaching environments (Acidithiobacillus, Leptospirillum, Sulfobacillus, Acidiphilium, Ferrimicrobium, and Acidimicrobium). Members from the genus Acidithiobacillus were dominant at all temperatures except 45 °C, at which Sulfobacillus spp. were dominant. Many of the acidithiobacilli are most closely related to strains of Acidithiobacillus ferrooxidans, and different strains were dominant under different experimental conditions, indicating considerable phenotypic heterogeneity within the species., Cet article porte essentiellement sur la caractérisation de la structure des communautés bactériennes présentes au cours de la biolixiviation en réacteurs agités d’un minerai de sulfure de nickel à faible teneur à différentes températures (de 5 à 45 °C) et à différents pH (3 et 5). Il s’agit de la suite de travaux antérieurs, dont le but était d’évaluer la faisabilité technique quant à l’utilisation de la biolixiviation à un pH élevé pour ce même minerai provenant du Manitoba (Canada). Une combinaison de techniques classiques microbiologiques et de biologie moléculaire a été utilisée pour identifier et recenser les membres des communautés bactériennes au cours des expériences menées pendant cinq semaines. Une analyse par électrophorèse en gel de gradient dénaturant (DGGE) a révélé la présence d’au moins 16 séquences distinctes de gènes d’ARNr 16S, dont 14 d’entre elles sont étroitement liées à des séquences existantes dans GenBank. Deux séquences détectées diffèrent grandement des séquences existantes dans GenBank et pourraient correspondre à de nouvelles espèces. Treize séquences sont liées à des séquences de gènes appartenant à des genres détectés antérieurement dans des milieux de biolixiviation (Acidithiobacillus, Leptospirillum, Sulfobacillus, Acidiphilium, Ferrimicrobium et Acidimicrobium). Les membres du genre Acidithiobacillus sont dominants à toutes les températures, sauf à 45 °C, température à laquelle ceux du genre Sulfobacillus spp. sont dominants. Bon nombre des acidithiobacilles sont les plus apparentés aux souches Acidithiobacillus ferrooxidans, et des souches différentes étaient dominantes sous différentes conditions expérimentales, ce qui indique une hétérogénéité phénotypique considérable au sein de l’espèce.

Despite the ubiquity of biofilms in natural and man-made environments, research on surface-associated cells has focused primarily on solid-liquid interfaces. This study evaluated the extent to which bacterial cells persist on inanimate solid-air interfaces. The desiccation tolerance of bacterial strains isolated from indoor air, as well as of a test strain (Pseudomonas aeruginosa), was determined at different levels of relative humidity (RH) using the large droplet inoculation method in an aerosol chamber. The cells survived longer at lower (25 and 42%) than at high RH (95%). Four of the seven indoor strains selected for further study showed extended period of survival following deposition as 0.05-0.1 ml of washed culture followed by desiccation, each with different effects on the survival of the test strain, P. aeruginosa. A strain closely related to Arthrobacter species afforded the highest level of protection to the test strain. Even though the desiccation-tolerant strains survived when they were deposited as bioaerosols, the protective role towards the test strain was not observed when the latter was deposited as a bioaerosol. These, which are often-unculturable, bacteria may go undetected during routine monitoring of biofouling, thereby allowing them to act as reservoirs and extending the habitat range of undesired microorganisms.

Corrigendum Corrigendum to “Bacterial community evidence for anaerobic degradation of petroleum hydrocarbons in cold climate groundwater” [Cold Reg. Sci. Technol., Volume 86 (2013) pp. 55–68] C. William Yeung, Dale R. Van Stempvoort, John Spoelstra, Greg Bickerton, John Voralek, Charles W. Greer⁎ a National Research Council Canada, 6100 Royalmount Ave., Montreal, Quebec, Canada H4P 2R2 b Water Science & Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6

The use of microbial communities in the conversion of cellulosic materials to bio-ethanol has the potential to improve the economic competitiveness of this biofuel and subsequently lessen our dependency on fossil fuel-based energy sources. Interactions between functionally different microbial groups within a community can expand habitat range, including the creation of anaerobic microenvironments. Currently, research focussing on exploring the nature of the interactions occurring during cellulose degradation and ethanol production within mixed microbial communities has been limited. The aim of this study was to enrich and characterize a cellulolytic bacterial community, and determine if ethanol is a major soluble end-product. Cellulolytic activity by the community was observed in both non-reduced and pre-reduced media, with ethanol and acetate being major fermentation products. Similar results were obtained when sterile wastewater extract was provided as nutrient. Several community members showed high similarity to Clostridium species with overlapping metabolic capabilities, suggesting clostridial functional redundancy.

Laboratory scale continuous-flow-through chambers (flow cells) facilitate the observation of microbes in a controlled, fully hydrated environment, although these systems often do not simulate the environmental conditions under which microorganisms are found. We developed a flow cell that mimics a subsurface groundwater-saturated rock fracture and is amenable to confocal laser scanning microscopy while allowing for the simple removal of the attached biomass. This flow cell was used to investigate the effect of toluene, a representative contaminant for non-aqueous phase liquids, on groundwater-derived biofilms. Reduced average biofilm biomass and thickness, and diminished diversity of amplifiable 16S rRNA sequences were observed for biofilms that developed in the presence of toluene, compared to the biofilms grown in the absence of toluene. The flow cell also allowed the detection of fluorescent protein-labelled cells.

The Hibernia production platform is the largest oil producing platform off the east coast of Canada. The produced water is the major source of contamination from the platform into the ocean. A comprehensive study on the potential impact of the produced water discharge is needed. Microorganisms can rapidly respond to change, whether negative or positive, and at the population level, are powerful indicators of change in their environment. The objective of this study was to characterize the indigenous microbial community structure, by denaturing gradient gel electrophoresis (DGGE), in the produced water and in seawater around the production platform, and to determine whether the release of produced water is impacting the natural ecosystem. The DGGE results showed that the production water did not have a detectable effect on the bacterial populations in the surrounding water. Cluster analysis showed a >90% similarity for all near surface water (2 m) samples, ~86% similarity for all the 50 m and near bottom (NB) samples, and ~78% similarity for the whole water column from top to bottom across a 50 km range, based on two consecutive yearly sampling events. However, there were distinct differences in the composition of the bacterial communities in the produced water compared to seawater near the production platform (~50% similar), indicating that the effect from produced water may be restricted to the region immediately adjacent to the platform. Specific microorganisms (Thermoanaerobacter for eubacteria and Thermococcus and Archaeoglobus for archaea) were detected as significant components of the produced water. These particular signature microorganisms may be useful as markers to monitor the dispersion of produced water into the surrounding ocean.