Methylmercury formation in

Overview

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Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

• Attribution License (CC BY). The use, (close to 50%), and medium/biofilm partitioning of inorganic Hg (Hg(II)) indicated low
• methylation in biofilms is important and will require controlled studies MgSO4, 8.8 μM CaCl2, 0.05 mM NaH2PO4, 1% (v/v) Wolfe’s trace metals
• were obtained within 40–44 h after bacterial inoculation (1%–2%) into images collected on samples from two separate experiments were used
• 2.2. Set-up for biofilm formation determined as the mean of the difference between local thickness (one
• nutritive media containing vertically placed acid-washed (15% HCl) were determined using the Student’s t-test in Microsoft Excel.
• nutritive medium amended with vitamins mixture (1% v/v, MD-VS™, glass slides were placed in 6 mL of the nutritive medium for cultivation.
• The range of conditions for biofilm formation experiments was selected voltage of 3 kV and a probe current of 50 pA. The images presented are
• 0.9% (w/v) NaCl, was spread on top of the glass slide with the biofilm. Rsample), where R is the internal reflectance. A spectrum of cell-free
• (50% in milli-Q water) was used to mount glass cover slips on top of the 3,580, 2,750, 1,800, and 900 cm−1 in OPUS 7.8 software.
• cells per image field was used for estimation of the approximate number 1 mg/L resazurin (Schaefer et al., 2014). The assay buffer was
• 25% (w/v) NaOH, whereas samples collected for total Hg quantification
• the vitamins mixture (1% v/v), washed twice with the assay buffer and samples without Hg addition. Bars represent MeHg produced of which
• samples of bacterial suspensions and samples that were filtered prior to the fraction of MeHg associated with biofilms was from 7 to 20% of the
• was found that all biofilms produced MeHg with on average ~ 8% of the loosely associated with glass surfaces were observed by naked eye when
• grown in medium with vitamins, where ~85% of the surface was covered surface, in agreement with the CLSM results. As shown in Figure 3C,
• et al., 2014). The surface coverage, biomass, and mean thickness found accordance with previous studies that have demonstrated extracellular
• in our work were 86 ± 10%, 8.9 ± 5.2 μm3/μm2, and 19 ± 7 μm, while those substances linking G. sulfurreducens cells in biofilms (Rollefson et al.,
• reported by Cologgi et al. (2014) were 92 ± 7%, 10.6 ± 3.3 μm3/μm2, and 2011; Cologgi et al., 2014).
• old biofilms, ~8% of the initially added Hg(II) was methylated reported Hg methylation rate constants in planktonic culture assays with
• result is comparable to the study of biofilms of a sulfate-reducing ~20% and 40% of km values reported previously for planktonic cells for
• close to 50% (2.5% and 3.3% of initially added Hg was found in biofilms CH3) and polysaccharides (νCO, C–O–C, P–O–C, R–O–P–O–R′) were
• proportion of MeHg to total Hg was reported to be <1% in biofilms Yunda and Quilès, 2019; Figure 5). Furthermore, the stable relative
• (Dranguet et al., 2017), <0.1% in an industrially contaminated freshwater 1220 cm−1, suggests that the cell number in biofilms likely remained
• creek (Schwartz et al., 2019), 11%–18% in a river affected by run-of-river unchanged throughout the assay. Hence, in accordance with the design
• power plants and artificial wetlands (Leclerc et al., 2021), as well as 12% of the assay, the experimental conditions allowed limiting cells growth
• and 57% in plant-associated biofilms in lake Titicaca (Bouchet et al., and strong changes in cells physiology.
• balance of total Hg and may explain why only 44% was recovered Hg(II) associated with cells in the biofilm was notably lower than the
• and methylmercury in littoral macroinvertebrates: a stable isotope approach. of methylmercury by anaerobic bacteria. Environ. Sci. Technol. Lett. 2, 292–296. doi:

Methods (brief)

• were obtained within 40–44 h after bacterial inoculation (1%–2%) into images collected on samples from two separate experiments were used
• based on earlier research of G. sulfurreducens biofilms grown on glass representative from a series recorded on duplicate samples.
• 0.9% (w/v) NaCl, was spread on top of the glass slide with the biofilm. Rsample), where R is the internal reflectance. A spectrum of cell-free
• incubation, samples were collected and spiked with Me200Hg or 200Hg for
• media samples. Samples of the medium surrounding biofilms were
• the vial for collecting the biofilm sample. Biofilms were scraped off the
• vortexed before splitting the samples in two for MeHg and total Hg
• analyses. Biofilms and media collected for MeHg analyses were
• 25% (w/v) NaOH, whereas samples collected for total Hg quantification
• Samples were stored at −20°C until analysis. If not stated otherwise,
• three replicate samples were prepared and statistically significant
• the vitamins mixture (1% v/v), washed twice with the assay buffer and samples without Hg addition. Bars represent MeHg produced of which
• samples of bacterial suspensions and samples that were filtered prior to the fraction of MeHg associated with biofilms was from 7 to 20% of the
• was determined using thermal desorption gas chromatography−ICPMS evolution of structural properties as a function of time, CLSM images of
• (TD-100 Markes – GC 7890B Agilent – ICP-MS 7700 Agilent) after biofilms cultivated for 3, 5, or 7 days in the three nutritive media were
• adjustment of samples pH to ~4.5 using 5 M HCl and 2 M CH3COONH4. taken (Figure 2). After 3 days of growth in standard nutritive medium,
• Samples were derivatized with NaB(C2H5)4, purged with N2 and trapped cells could be seen dispersed in a ~17 μm thick layer covering ~32% of
• CETAC HGX-200 cold vapor system coupled with ICPMS (8900 colonies were distributed. Colony formation in biofilms is one strategy

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

• Shellfish (shrimp, crab, lobster, clams, oysters, mussels)
• Mercury
• Mercury

Verification notes

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.