Impacts of anthropogenic gadolinium on the activity of the ammonia oxidizing bacterium Nitrosomonas europaea.

Widespread use of gadolinium-based contrast agents in medical imaging has resulted in increased Gd inputs to municipal wastewater treatment plants. Others have reported that typical wastewater treatment does not attenuate Gd, resulting in discharges to natural waters. However, whether elevated Gd impacts the performance of biological treatment has not been investigated. We examined whether gadolinium chloride or Gd chelated with diethylenetriaminepentaacetic acid (DTPA) affected the activity of the model nitrifying bacterium Nitrosomonas europaea. At nominal GdCl3 additions ranging from 1 to 500 µM, no impact was observed compared to the control. Most (>98%) of the added Gd precipitated, and extracellular GdPO4 nanoparticles were observed. When chelated with DTPA, Gd remained soluble, but no statistically significant impact on ammonia oxidation was observed until the highest concentrations tested. At 300 and 500 µM Gd-DTPA, a temporary reduction of nitrite production relative to the control (effect size 1.3 mg l-1 and 1.5 mg l-1, respectively, at 24 h) was seen. By itself, DTPA was highly inhibitory. Modeling suggested that DTPA likely chelated other metals, but adjusting the concentrations of the most abundant metals in the medium, calcium and magnesium, indicated that lowering their free ion activities was probably not the cause of inhibition. Complexation of other essential metals was more likely. Our studies indicate that while the low bioavailability of Gd may limit its ecosystem impacts, the role of synthetic ligands used with Gd and other rare earth elements should be considered as the production, use and disposal of these elements increases.

Do patients living with ulcerative colitis adhere to healthy eating guidelines? A cross-sectional study.

Ulcerative colitis (UC) is an inflammatory bowel disease that causes gastrointestinal lesions, bleeding, diarrhoea and nutritional complications. Insufficient nutrient intake can additionally deteriorate nutritional status. The present cross-sectional study aimed to determine whether UC patients adhere to national dietary guidelines and to assess their dietary habits. An online questionnaire (n 93) was used to assess health-related conditions, current nutritional knowledge, professional dietary guidance and food avoidance. A 24 h dietary recall (n 81) was used to assess nutrient intakes, which were then compared with the national recommended intake values. The results showed that the nutritional knowledge of participants was limited with unofficial sources being used, including websites. Numerous food groups, predominantly fibre-rich foods and fruit and vegetables, were largely avoided by the participants. Almost half of the study population eliminated foods such as dairy products to alleviate symptoms, possibly unnecessarily. Energy intakes were significantly (P< 0·05) lower than the national recommended intake values in women aged 18-65 years and men aged 18-60 years. Fat intake exceeded the national recommended intake values (P< 0·0001), at the expense of carbohydrate and fibre intakes, which were significantly (P< 0·005) lower than the national recommended intake values. Protein intake was significantly high in women aged 19-50 years (P< 0·00) and men aged 19-50 years (P< 0·005). Vitamin C, vitamin B12 and Ca intake levels were overachieved by all participants (P< 0·001), while women aged 19-50 years did not achieve their dietary Fe reference nutrient intake levels (P< 0·001). Osteopaenia, osteoporosis and anaemia were reported by 12, 6 and 31 % of the participants, respectively. Findings indicate that food avoidance may contribute to nutrient deficiencies in UC patients. Low intakes of these food groups, especially during remission, are preventing patients from adhering to dietary guidelines.

Calcium carbonate formation by Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807.

Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the genus Synechococcus represents a potential mechanism for sequestration of atmospheric CO2 produced during the burning of coal for power generation. Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested in microcosm experiments for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and dissolved inorganic carbon concentrations of 0.5, 1.25 and 2.5 mM. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment producing approximately 18.6 mg of solid phase calcium. Calcium removal occurred over a two-day time period when Synechococcus sp. strain PCC 8807 was tested and only 8.9 mg of solid phase calcium was produced. Creation of an alkaline growth environment catalyzed by the physiology of the cyanobacteria appeared to be the primary factor responsible for CaCO3 precipitation in these experiments.

Biological and chemical interactions with U(VI) during anaerobic enrichment in the presence of iron oxide coated quartz.

Microcosm experiments were performed to understand chemical and biological interactions with hexavalent uranium (U(VI)) in the presence of iron oxide bearing minerals and trichloroethylene (TCE) as a co-contaminant. Interactions of U(VI) and hydrous iron oxide moieties on the mineral oxide surfaces were studied during enrichments for dissimilatory iron reducing (DIRB) and sulfate reducing bacteria (SRB). Microbes enriched from groundwater taken from the Test Area North (TAN) site at the Idaho National Laboratory (INL) were able to reduce the U(VI) in the adsorption medium as well as the iron on quartz surfaces. Early in the experiment disappearance of U(VI) from solution was a function of chemical interactions since no microbial activity was evident. Abiotic removal of U(VI) was enhanced in the presence of carbonate. As the experiment proceeded, further removal of U(VI) from solution was associated with the fermentation of lactate to propionate and acetate. During later phases of the experiment when lactate was depleted from the growth medium in the microcosm containing the DIRB enrichments, U(VI) concentrations in the solution phase increased until additional lactate was added. When additional lactate was added and fermentation proceeded, U(VI) concentrations in the liquid phase again returned to near zero. Similar results were shown for the SRB enrichment but lower uranium concentrations were seen in the liquid phase, while in the enrichment with carbonate a similar increase in uranium concentration was not seen. Chemical and biological interactions appear to be important on the mobilization/immobilization of U(VI) in an iron oxide system when TCE is present as a co-contaminant. Interestingly, TCE present in the microcosm experiments was not dechlorinated which was probably an effect of redox conditions that were unsuitable for reductive dechlorination by the microbial culture tested.

Screening of cyanobacterial species for calcification.

Species of cyanobacteria in the genera Synechococcus and Synechocystis are known to be the catalysts of a phenomenon called "whitings", which is the formation and precipitation of fine-grained CaCO3 particles. Whitings occur when the cyanobacteria fix atmospheric CO2 through the formation of CaCO3 on their cell surfaces, which leads to precipitation to the ocean floor and subsequent entombment in mud. Whitings represent one potential mechanism for CO2 sequestration. Research was performed to determine the ability of various strains of Synechocystis and Synechococcus to calcify when grown in microcosms amended with 2.5 mM HCO(3-) and 3.4 mM Ca2+. Results indicated that although all strains tested have the ability to calcify, only two Synechococcus species, strains PCC 8806 and PCC 8807, were able to calcify to the extent that a CaCO3 precipitate was formed. Enumeration of the cyanobacterial cultures during testing indicated that cell density did not appear to have a direct effect on calcification. Factors that had the greatest effect on calcification were CO2 removal and subsequent generation of alkaline pH. Whereas cell density was similar for all strains tested, differences in maximum pH were demonstrated. As CO2 was removed, growth medium pH increased and soluble Ca2+ was removed from solution. The largest increases in growth medium pH occurred when CO2 levels dropped below 400 ppmv. Research presented demonstrates that, under the conditions tested, many species of cyanobacteria in the genera Synechocystis and Synechococcus are able to calcify but only two species of Synechococcus were able to calcify to an extent that led to the precipitation of calcium carbonate.