Role of in Situ Natural Organic Matter in Mobilizing As during Microbial Reduction of FeIII-Mineral-Bearing Aquifer Sediments from Hanoi (Vietnam).

Natural organic matter (NOM) can contribute to arsenic (As) mobilization as an electron donor for microbially-mediated reductive dissolution of As-bearing Fe(III) (oxyhydr)oxides. However, to investigate this process, instead of using NOM, most laboratory studies used simple fatty acids or sugars, often at relatively high concentrations. To investigate the role of relevant C sources, we therefore extracted in situ NOM from the upper aquitard (clayey silt) and lower sandy aquifer sediments in Van Phuc (Hanoi area, Vietnam), characterized its composition, and used 100-day microcosm experiments to determine the effect of in situ OM on Fe(III) mineral reduction, As mobilization, and microbial community composition. We found that OM extracted from the clayey silt (OMC) aquitard resembles young, not fully degraded plant-related material, while OM from the sandy sediments (OMS) is more bioavailable and related to microbial biomass. Although all microcosms were amended with the same amount of C (12 mg C/L), the extent of Fe(III) reduction after 100 days was the highest with acetate/lactate (43 ± 3.5% of total Fe present in the sediments) followed by OMS (28 ± 0.3%) and OMC (19 ± 0.8%). Initial Fe(III) reduction rates were also higher with acetate/lactate (0.53 mg Fe(II) in 6 days) than with OMS and OMC (0.18 and 0.08 mg Fe(II) in 6 days, respectively). Although initially more dissolved As was detected in the acetate/lactate setups, after 100 days, higher concentrations of As (8.3 ± 0.3 and 8.8 ± 0.8 µg As/L) were reached in OMC and OMS, respectively, compared to acetate/lactate-amended setups (6.3 ± 0.7 µg As/L). 16S rRNA amplicon sequence analyses revealed that acetate/lactate mainly enriched Geobacter, while in situ OM supported growth and activity of a more diverse microbial community. Our results suggest that although the in situ NOM is less efficient in stimulating microbial Fe(III) reduction than highly bioavailable acetate/lactate, it ultimately has the potential to mobilize the same amount or even more As.

ALIGNed on adherence: subanalysis of adherence in immune-mediated inflammatory diseases in the DACH region of the global ALIGN study.

BACKGROUND: Non-adherence to medication is a challenging problem in daily clinical practice. OBJECTIVE: To assess reasons for non-adherence in patients with chronic immune-mediated inflammatory diseases (IMIDs) in a direct comparison including evaluation of treatment necessity and concerns. METHODS: ALIGN was a non-interventional, multicountry, multicentre, self-administered, cross-sectional, epidemiologic survey study. Here, we investigate the German, Austrian and Swiss (DACH) cohort. Six hundred thirty-one patients with different IMIDs (rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, plaque psoriasis, Crohn's disease and ulcerative colitis) under systemic therapies were evaluated concerning adherence, beliefs of necessity and concerns towards treatment in patients with IMIDs. RESULTS: The DACH cohort had significantly different levels of adherence depending on the IMID (P < 0.05) and the type of therapy (P < 0.05). Based on the significant influence of concerns on treatment adherence (P < 0.05) and the high belief of treatment necessity, patients could be classified in four attitudinal segments, which were unequally distributed throughout various IMIDs. High concerns had a significant influence on non-adherence, whereas necessity did not. Older age, female sex, TNFi mono-, conventional combination and TNFi combination therapy are positively associated with adherence. CONCLUSIONS: In the DACH region, patients are less concerned about medication and believe in the necessity of treatment. Therefore, we suggest adapting the communication in the various patient groups.

Insights into Nitrate-Reducing Fe(II) Oxidation Mechanisms through Analysis of Cell-Mineral Associations, Cell Encrustation, and Mineralogy in the Chemolithoautotrophic Enrichment Culture KS.

Most described nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB) are mixotrophic and depend on organic cosubstrates for growth. Encrustation of cells in Fe(III) minerals has been observed for mixotrophic NRFeOB but not for autotrophic phototrophic and microaerophilic Fe(II) oxidizers. So far, little is known about cell-mineral associations in the few existing autotrophic NRFeOB. Here, we investigate whether the designated autotrophic Fe(II)-oxidizing strain (closely related to Gallionella and Sideroxydans) or the heterotrophic nitrate reducers that are present in the autotrophic nitrate-reducing Fe(II)-oxidizing enrichment culture KS form mineral crusts during Fe(II) oxidation under autotrophic and mixotrophic conditions. In the mixed culture, we found no significant encrustation of any of the cells both during autotrophic oxidation of 8 to 10 mM Fe(II) coupled to nitrate reduction and during cultivation under mixotrophic conditions with 8 to 10 mM Fe(II), 5 mM acetate, and 4 mM nitrate, where higher numbers of heterotrophic nitrate reducers were present. Two pure cultures of heterotrophic nitrate reducers (Nocardioides and Rhodanobacter) isolated from culture KS were analyzed under mixotrophic growth conditions. We found green rust formation, no cell encrustation, and only a few mineral particles on some cell surfaces with 5 mM Fe(II) and some encrustation with 10 mM Fe(II). Our findings suggest that enzymatic, autotrophic Fe(II) oxidation coupled to nitrate reduction forms poorly crystalline Fe(III) oxyhydroxides and proceeds without cellular encrustation while indirect Fe(II) oxidation via heterotrophic nitrate-reduction-derived nitrite can lead to green rust as an intermediate mineral and significant cell encrustation. The extent of encrustation caused by indirect Fe(II) oxidation by reactive nitrogen species depends on Fe(II) concentrations and is probably negligible under environmental conditions in most habitats.IMPORTANCE Most described nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB) are mixotrophic (their growth depends on organic cosubstrates) and can become encrusted in Fe(III) minerals. Encrustation is expected to be harmful and poses a threat to cells if it also occurs under environmentally relevant conditions. Nitrite produced during heterotrophic denitrification reacts with Fe(II) abiotically and is probably the reason for encrustation in mixotrophic NRFeOB. Little is known about cell-mineral associations in autotrophic NRFeOB such as the enrichment culture KS. Here, we show that no encrustation occurs in culture KS under autotrophic and mixotrophic conditions while heterotrophic nitrate-reducing isolates from culture KS become encrusted. These findings support the hypothesis that encrustation in mixotrophic cultures is caused by the abiotic reaction of Fe(II) with nitrite and provide evidence that Fe(II) oxidation in culture KS is enzymatic. Furthermore, we show that the extent of encrustation caused by indirect Fe(II) oxidation by reactive nitrogen species depends on Fe(II) concentrations and is probably negligible in most environmental habitats.

A computer program for comparative analysis of nucleic acid sequences.

The programs offer the possibility of comparing pairs of homologous sequences in order to find out percentage of homology, number of identical and deviating nucleotides, of transitions and transversions and, derived from these, KNUC-values according to Kimura (1) and the corresponding standard error sigmaK. The sequences can be printed in pairs underneath each other, homologies are indicated by asterisks between the identical nucleotides. Out of a set of homologous sequences stored on a disk any number of sequences can be compared in pairs in this way, and a matrix containing either the percentage of homology values, the number of deviating nucleotides or the KNUC-values together with the corresponding standard errors can be sent to screen, printer or disk. A program will be available soon which creates a dendrogram representing the similarity between the sequences by use of an average linkage clustering method deduced from this matrix. The programs are written for Apple II computers using UCSD-PASCAL and for Sirius I/Victor 9000 computers using TURBO-PASCAL.

Impaired humoral immune response in complement C3-deficient guinea pigs: absence of secondary antibody response.

A recently described genetically controlled C3 deficiency (C3D) in guinea pigs (GP) provided a unique model for studying the role of C3 in the afferent limb of the humoral immune response in a direct manner. These C3D animals, which have only 5-7% of normal serum C3 level, were immunized with the bacteriophage phi chi 174, a T cell-dependent antigen, followed by a booster injection after 4 weeks (1.5 X 10(9) plaque-forming units/kg). The formation of IgM and IgG antibody in the course of the primary and secondary response was determined and compared with a control group of inbred strain 2 GP. The C3D animals showed a markedly diminished antibody response to this antigen. Amplification of the antibody titer as well as regular isotype switching from IgM to IgG was absent in the secondary response. Increasing the amount of antigen to a high dose (1 X 10(10) plaque-forming units/kg) led to a normalization of the antibody response. The impairment in antibody formation resembles closely the impaired antibody response in C4-deficient or C2-deficient GP, which both have a block in activation of C3 via the classical pathway. However, in contrast to C4D GP or C2D GP the C3D GP do not exhibit serological characteristics of immune complex disease. They have normal levels of total serum IgM, of IgM anti-2,4-dinitrophenyl antibodies and of IgM rheumatoid factors.