Rhizosphere Processes for Heavy Metal Remediation

Overview

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Key numbers

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Sulfur-reducing bacteria precipitate metals as insoluble sulfides with 90% efficiency. In
conditions of the Creative Commons Global urbanization has reached a tipping point with a current 58% of the total
Attribution (CC BY) license. population living in the cities as compared to 46.7% in 2000 (1). This demographic shift,
required to increase the food production by 35% to 56% by 2050 (5). Soil quality and
metals (7), potentially affecting 14% to 17% of global farmland (8).
to a wide range of metals forming high-affinity PC–metal complexes (34). In addition,
surfaces for metal cations across a wide pH range (11). Peptidoglycan polymer in bacterial
highly suitable for biosorption of metals such as Pb2+ and Cd2+ (50). Although biosorption
and Rossellomorea strains, particularly for Cd2+ , Pb2+ , Cu2+ , Ni and Cr species (Table 1). As
Table 1. The effectiveness of heavy metal removal by microbes and detoxification mechanisms. Metal
Pb Oceanobacillus profundus KBZ 3–2 97% removal (82)
Pb Biosorption ≈85.95–86.78% removal (83)
Pb Bacillus subtilis Biosorption Qmax ≈ 61.8 mg/g (≈96.1%) (84)
Hg Pseudomonas sp. B50A MerA reduction 86% removal (98)
Hg Pseudomonas aeruginosa FZ-2 merA expression ≈91% removal (100)
Hg Mixed Yellow River isolates Mer operon reduction ≤0.05 mg/L–10 mg/L (101)
Hg Bacillus sp. LBA119 Volatilization + biosorption 97.3% removal (102)
Hg Rheinheimera metallidurans Mercuric reductase ≈92% removal (103)
As Delftia tsuruhatensis K7 Oxidation + adsorption 92.4% oxidation (107)
Mn Serratia marcescens QZB-1 Biosorption + oxidation 91.8% Mn removal (60)
Mn Bacillus wiedmannii Biosorption 91.96% Mn removal (112)
cations as insoluble metal sulfides and effectively removes (>90%) Cd2+ , Pb2+ , Ni2+ , Fe2+ ,
The data presented in Table 2 demonstrate that SRB, especially Desulfovibrio-dominated
consortia, exhibited high metal removal efficiencies (>90–100%) including Cd2+ , Pb2+ ,
(e.g., Ni2+ > 400 mg/L and Fe2+ > 800 mg/L). Optimal metal remediation efficiency has
Table 2. Efficiency of sulfate-reducing bacteria/consortia in removing the heavy metals/metalloids
oxide also improved Cr(VI) removal by Bacillus cereus ZNT-03 by up to 72%, by providing
Table 3. Role of organic amendments in microbial- and consortia-based microbial Cr(VI) reduction
Galactose 4% 2 mM 100% (16)
Stenotrophomonas Lactose, fructose, 1000 mg/L ≈42%
Bacillus sp. M6 20 mg/L mediated mechanisms and (162)
CRB-B1 glucose 10 g/L >76% mediated by extracellular
biochar (prepared 1 g/L 10 mg/L 80% cellular proteins assist (167)
Bacillus cereus RC ferric citrate 1.5 50 mg/L ~83% enhancement rather than final (168)
oxalate, 0.05 M 96%
consortia (Not H2 :CH4 (1:1 ratio) through a needle 10 mg/L >95% Cr(VI) reduction, (171)
soil microbes– Yeast extract 200 mg/L 1000 µg/L 100%
Molasses Not specified 25 mg/L 100% (173)
Indigenous Yeast extract 200 mg/L 134 µg/L 100%
Yeast extract 200 mg/L 1000 µg/L 100% (166)
Data compiled in Table 3 from various studies showed Cr(VI) ranges from 55.4 to
1. Consortium exhibited 95% Cr(VI) reduction efficiency compared to individual strains

Methods (brief)

Mn Bacillus wiedmannii Biosorption 91.96% Mn removal (112)
Soil samples from the grassland of Jiangnan ≈88 (65 in +Cd20) 1.4×
was collected P 15 mg/kg P treatment in the roots with 30 to
to 39.6% forms, i.e., DMAA
collected -Increasing P resulted concentrations could play
Soil was collected from the
Soils were collected from a CAT) reduced membrane
1. Yaashikaa, P.R.; Senthil Kumar, P.; Mohan Babu, V.P.; Kanaka Durga, R.; Manivasagan, V.; Saranya, K.; Saravanan, A. Modelling
1. Wang, J.; Zhao, F.-J.; Meharg, A.A.; Raab, A.; Feldmann, J.; McGrath, S.P. Mechanisms of Arsenic Hyperaccumulation in Pteris
1. Yaashikaa, P.R.; Kumar, P.S.; Jeevanantham, S.; Saravanan, R. A Review on Bioremediation Approach for Heavy Metal Detoxifica-

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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.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised