Reduction of Hexavalent Chromium by

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:

• Funding: PKUU‐PT QS WUR Universitas Sumatera Utara, Grant/Award Number: 7092.1/UNS.1.R/PPM/2023; BRIN‐LPDP (Indonesia Endowment Fund for
• et al. 2016). Once released, Cr(VI) can travel through air, soil, hundred mg/L of Cr(VI), Bacillus sp. MH778713 exhibits a
• by redox potential, organic matter, and metal oxides. These 15.000 mg/L (Ramírez et al. 2019). This tolerance is frequently
• unless effectively remediated (Briffa et al. 2020). rapid reduction rates of up to 11.11 mg/L/h and can completely
• While existing conventional physicochemical treatments such remove 200 mg/L of Cr(VI) within 18 h (Gu et al. 2023). The
• tion (Genawi et al. 2020), and nanoparticle‐based adsorption wide range of sites, including tannery effluents (Elahi et al. 2022),
• reduction rates as high as 6.39/mg/L/h (Baldiris et al. 2018). In such as iron (Tochetto et al. 2024), aluminium (Tejada tovar
• PCBs, the reduction rate can drop as low as 0.019 mg/L/h in et al. 2021), and titanium (X. Zhang et al. 2023). This technique
• toxic or more soluble forms through biotransformation. et al. 2004). Meanwhile, in Staphylococcus aureus, the nfoR gene
• cellular thiols such as glutathione (GSH) can reduce Cr(VI) chromium‐reducing species (Table 1) with strains frequently
• TABLE 1 | Reduction performance of Cr(VI) by Stenotrophomonas strains across reported conditions and key findings.
• S. maltophilia OS4 100 mg/L 7.0 35 48 h 91% ~1.90 High tolerance (1200 mg/L); likely Oves et al. (2013)
• S. maltophilia SRS05 490 mg/L (in 7.0 35 15 days 46.9% ~0.64 Focus on bioadsorption in real tannery Raman et al. (2018);
• Stenotrophomonas sp. JD1 300 mg/L Not 30 90 h 30% ~1.00 Protective mechanisms: EPS production & (Morel et al. (2009))
• Stenotrophomonas sp. D6 200 mg/L 9.0 35 72 h 100% ~2.78 Extremely high tolerance (1,600 mg/L); Ge et al. (2015)
• S. rhizophila JC1 40 mg/L 7.0 35 24 h ≈0% N/A Important negative result. Effective for S.‐C. Sun et al. (2021)
• S. rhizophila PM6/PM7 5 mg/L (in LB Not 30 48 h 81‐82% ~0.085 High efficiency at low conc. in rich media, Denaro et al. (2025)
• Stenotrophomonas sp. 88.5 mg/L 7.0 37 72 h 96% ~1.18 Statistical optimization (RSM) significantly Shreif et al. (2022)
• S. maltophilia ZA‐6 ~26 mg/L 7.2 30 56 h 100% ~0.46 Intracellular enzymatic (NADH‐ Alam and
• Stenotrophomonas sp. 16.59 mg/L 7.38 ~32 4.07 days 81.3% ~0.14 Simultaneous reduction with phenol as Dharmaraj and
• S. acidaminiphila 4‐1 0.2 mg/g (in soil) Not 30 7 days 74.9% N/A (soil) Enhanced removal in soil using biochar Wang et al. (2024)
• Stenotrophomonas sp. D6 100 mg/L 9.0 30 28 h 98.5% ~3.52 Medium modification (replacing NaCl with Zha et al. (2024)
• S. rhizophila DSM14405T 50 mg/L 7.5 30 28 h 100% ~1.79 Transcriptomic analysis revealed resistance Gao et al. (2020)
• JC1, despite tolerating up to 40 mg/L of chromium, showed no
• ~0.019 ~0.068 ~6.39 ~0.144 can also increase local pH, creating microenvironments suitable
• 58% 75.7% 92% 100% tor. Some contaminants, such as phenol (Dharmaraj and
• Removal (%) Muthukumar 2013) and diesel (L. Li et al. 2021), can act as
• (Zha et al. 2024). These cellular and enzymatic processes are not from a wide range of chromium‐polluted and extreme en­
• mutually exclusive and may occur sequentially, as seen in S. vironments (Table 2), including chromite mines (Dhal
• constitutive in Stenotrophomonas sp. TD3 (S. Ge and Ge 2016), with MICs typically ranging from 500 to 2500 mg/L. Notably,
• suggesting that some strains are constantly prepared for chromium B. paramycoides Cr6 tolerates up to 2500 mg/L and completely
• detoxification. Whole‐genome sequencing has also been informa­ reduces 200 mg/L Cr(VI) within 18 h, achieving an exceptional
• tive; Sun et al. (2021) confirmed the absence of known reductase rate of ~11.11 mg/L·h⁻¹ (Gu et al. 2023). Similarly, B. cereus
• genes in the non‐reductive S. rhizophila JC1, directly linking Cr(VI) b‐525k tolerates up to 1664 mg/L and achieves 99% reduction
• to Cr(VI) stress. In S. rhizophila DSM14405, Cr(VI) exposure 15,000 mg/L, relying primarily on bioaccumulation and bio­
• ciency, up to 98%–100% reduction, under neutral to alkaline
• erance to chromium (MIC > 7400 mg/L; Baldiris et al. 2018).
• at an approximate rate of ~11.11 mg/L·h⁻¹ (Gu et al. 2023).
• reduction of 50 mg/L Cr(VI) within 24 h (Zhu et al. 2019). Like­
• enabled near‐complete reduction of 10.4 mg/L Cr(VI) (Zheng
• consortium reached 92% total chromium removal under alka­
• of 50 mg/L Cr(VI) within 5 h by a sludge‐enriched community

Methods (brief)

• Bacillus wiedmannii SA1 Bacillus cereus ZY‐2009
• Genawi, N. M., M. H. Ibrahim, M. H. El‐Naas, and A. E. Alshaik. 2020.
• Stefánsson, A., I. Gunnarsson, H. Kaasalainen, and S. Arnórsson. 2015. Wang, C., H. Tan, H. Li, et al. 2020. “Mechanism Study of Chromium

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

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Cadmium
• Arsenic
• Aluminum
• Chromium

Verification notes

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Update history

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