Following emergence of the SARS-CoV-2 variant Omicron in November 2021, the dominant BA.1 sub-lineage was replaced by the BA.2 sub-lineage in Denmark. We analysed the first 2,623 BA.2 cases from 29 November 2021 to 2 January 2022. No epidemiological or clinical differences were found between individuals infected with BA.1 versus BA.2. Phylogenetic analyses showed a geographic east-to-west transmission of BA.2 from the Capital Region with clusters expanding after the Christmas holidays. Mutational analysis shows distinct differences between BA.1 and BA.2.

The concentration of sulfate in seawater exceeds all other dissolved electron acceptors combined by more than an order of magnitude. This allows dissimilatory sulfate reduction to persist in marine sediment long after the reactive species of more energetically favorable electron acceptors have been depleted. Thus, sulfate reduction dominates anaerobic carbon oxidation in most coastal and estuarine sediments worldwide (Goldhaber and Kaplan 1975;Jørgensen 1977 Jørgensen , 1982Canfield 1993). The relative importance of sulfate reduction decreases at low sedimentation rates because slowly deposited sediments are exposed to oxygen, nitrate and oxidized metals for a longer time after deposition, and because the degradability of dead organic matter decreases steeply during aging (Middelburg 1989). Sulfate reduction in deep-sea sediments therefore only contribute minutely to the global sulfur cycling (Canfield et al. 2005; Jørgensen and Kasten 2006) but deeply buried sediments with low metabolic activity still comprise a vast volume and the carbon mineralization in these sediments exerts major control on the climate and the chemistry of the planet.Direct determination of sulfate reduction rates by measuring the decreasing sulfate concentration over time in a closed vial is possible in limnic sediment (e.g., Bak et al. 1991), but it is not practical in marine sediments due to the high sulfate concentration in seawater (28 mmol L -1 ). Typical sulfate reduction rates in coastal surface-sediments are in the order of 20 nmol SO 4 2-cm -3 d -1 (Jørgensen 1982). With near 20 μmol SO 4 2-cm -3 in the sediment this implies that a 1% reduction in sulfate content requires impractically long incubation for days to months. The slow relative change in sulfate concentration is, however, turned to an advantage with radiotracer-based methods because the specific activity of the tracer remains nearly constant throughout the experiment. Because only the added tracer is measured, the high background concentration of sulfate and sulfides is of little concern. Here we re-evaluate the 35 SO 4 2-based measurement of sulfate reduction in marine sediments that has developed into a standard method over the last 30 years. Theoretical basisThe high activation energy of SO 4 2-makes microbial reduction through enzymatic catalysis the only pathway of sulfate reduction within the physiological temperature range in marine sediments. Various organisms are capable of assimila- AbstractRates of dissimilatory sulfate reduction in aquatic sediments have been measured over many years with 35 Sradiotracer, and the method has been continuously modified and optimized. This article discusses the sequence of procedures that constitutes the method from sediment handling before incubation, via incubation and distillation, to statistical analysis of the results. We test modifications that have been added since previous method descriptions, and we recommend sound experimental procedures. We discuss the measurement of extremely low sulfate reduction rates whereby o...

New lineages of SARS-CoV-2 are of potential concern due to higher transmissibility, risk of severe outcomes, and/or escape from neutralizing antibodies. Lineage B.1.1.7 (the Alpha variant) became dominant in early 2021, but the association between transmissibility and risk factors, such as age of primary case and viral load remains poorly understood. Here, we used comprehensive administrative data from Denmark, comprising the full population (January 11 to February 7, 2021), to estimate household transmissibility. This study included 5,241 households with primary cases; 808 were infected with lineage B.1.1.7 and 4,433 with other lineages. Here, we report an attack rate of 38% in households with a primary case infected with B.1.1.7 and 27% in households with other lineages. Primary cases infected with B.1.1.7 had an increased transmissibility of 1.5–1.7 times that of primary cases infected with other lineages. The increased transmissibility of B.1.1.7 was multiplicative across age and viral load.

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Studies of the kinetics of dissimilatory sulfate reduction in marine sediment have shown that a mixture of marine sulfate-reducing bacteria (SRB) can reduce sulfate with both a high and low apparent sulfate half-saturation constant (Km). However, all marine pure cultures investigated have shown only low-sulfate affinity sulfate reduction kinetics. It remains unknown whether marine high sulfate-affinity sulfate reduction is catalyzed by unknown SRB or whether known SRB possess unrecognized high-affinity sulfate reduction systems. We used 35S-sulfate incubation experiments to show that cultures of Desulfobacterium autotrophicum HMR2 will switch from low-affinity to high-affinity sulfate reduction when sulfate concentrations fall below 500 μM. The mean Km was 150 μM at high sulfate concentrations and 8 μM at low sulfate concentrations. The high-affinity Km value is comparable to values found in SRB inhabiting freshwater sediments and D. autotrophicum cultures could deplete sulfate to below our detection limit of 25 nM. The switch in Km value was accompanied by a change in the expression of genes encoding membrane-bound transport proteins putatively involved in sulfate uptake in D. autotrophicum. Our results demonstrate that a marine sulfate reducer can efficiently reduce sulfate at both high and low sulfate concentrations, possibly by activation of different sulfate transporters in the membrane.