Characterization of the differentiated reduction of selenite and tellurite by a halotolerant bacterium: Process and mechanism

Riboflavin secreted by Shewanella sp. FDL-2 facilitates its reduction of Se(iv) and Te(iv) by promoting electron transfer

“…In the Te( iv )-supplemented system, the upregulated expression of functional genes of strain FDL-2 lagged slightly behind that in the Se( iv )- supplemented system, which may be attributed to the toxicity of Te( iv ) being greater than that of Se( iv ). Similar to previous reports, 9 some reductases and cytochromes, including frdA (10.0-/8.3-fold), SDHA (11.9-/4.7-fold), cytC (6.8-/5.3-fold) nrfG (6.7-/6.8-fold), tsdA (11.1-/10.0-fold) etc. showed significantly upregulated expression during both Se( iv ) and Te( iv ) exposure (fold change in Se( iv )-added system/fold change in Te( iv )-added system).…”

“…To date, increasing terrestrial and marine bacterial resources have been identified to be capable of reducing Se( iv ) and Te( iv ) to Se 0 and Te 0 . 8–13 Some of the more studied bacterial genera include Shewanella , Pseudomonas , Bacillus , Pseudoalteromonas , Acinetobacter , etc. They differ not only in their ability to reduce Se( iv ) and Te( iv ) but also in their reduction mechanisms.…”

“…For Se 0 and Te 0 measurements, the pellets were washed with 1 M NaCl three times to remove Se( iv )/Te( iv ) and then treated with sonication (30 s sonication, 30 s pause, 30 min) in an ice bath; after that, the pellet was centrifuged (6000 rpm, 8 min), the supernatant was discarded, and the pellet was washed twice with 10 mL of NaCl (1 M), resuspended in 1 mL of Na 2 S (1 M, red solution for Se 0 measurement) or 1 mL of KOH (1 M, black solution for Te 0 measurement), and finally determined at 500 nm and 340 nm. 9 Se( iv ) and Te( iv ) concentrations were measured at 500 nm and 340 nm following the methods described by Arindam et al (2022) 16 and Mal et al (2017), 17 respectively. In addition, the electron transport system activity (ETSA) was detected according to a previously reported method.…”

“…Different environmental factors, including dissolved oxygen concentrations (adjusted by 100-500 mL of medium volumes), carbon sources (C1-C6 compounds, including sodium formate, sodium acetate, sodium pyruvate, sodium lactate, glucose), salt concentrations (0-5%, m/v) and pH values (3)(4)(5)(6)(7)(8)(9)(10), were applied to investigate their effects on the growth of strain FDL-2. Samples were taken at intervals to record the growth of cells.…”

The cryptic step in biogeochemical Tellurium (Te) cycle: Indirect elementary Te oxidation mediated by manganese-oxidizing bacterium (MnOB)

“…Therefore, Te 0 was confirmed as the main product of Te(IV) reduction by strain FF-1 as the other Te(IV) reducing bacteria did. 6, 28 The residual Te(IV) in the solids may source from the Te(IV) adsorption at the surface of bacteria or BioTe 0 . On the other hand, no detectable methyl tellurides were found by GC after incubation for 168 h, and no homologous gene encoding for bacteria thiopurine methyltransferases was identified from the genome of strain FF-1.…”