University of Technology Malaysia, Malaysia Lana Abbas , Oliver Coutinho , Aleksa Fortuna , Fatima Sulaiman ,

Overview

This source page is a mechanical bulk-ingest record for a PDF in the methylmercury infant-formula research pull. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

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RECEIVED 17 August 2023 Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, MI, United States
and biosorption characteristics of four bacterial strains (Serratia sp. L2, Raoultella
Farinas J, Schittenhelm R, Catalfano B, Li X and sp. L30, Klebsiella sp. R3, and Klebsiella sp. R19) isolated from Saint Clair River
Tiquia-Arashiro SM (2023) Metal tolerance and sediments. These strains effectively removed various metal cations (As3+, Pb2+,
Cu2+, Mn2+, Zn2+, Cd2+, Cr6+, and Ni2+) in single and multi-metal solutions. Minimum
Front. Microbiol. 14:1278886. inhibitory concentration (MIC) assays revealed strain-specific variations in metal
doi: 10.3389/fmicb.2023.1278886 tolerance, with L2 and L30 exhibiting higher tolerance. Surprisingly, R3 and
COPYRIGHT R19, despite lower tolerance, demonstrated superior metal removal efficiency,
© 2023 Pagnucco, Overfield, Chamlee, Shuler, challenging the notion that tolerance dictates removal efficacy. In single-metal
solutions, R3 and R19 excelled at extracting various metal ions, while competitive
Catalfano, Li and Tiquia-Arashiro. This is an binding in multi-metal solutions hindered removal. However, R3 and R19 retained
in metal distribution patterns between Klebsiella sp. R19 and Raoultella sp. L30
Frontiers in Microbiology 01 frontiersin.org
Pagnucco et al. 10.3389/fmicb.2023.1278886
1. Introduction development of microbial processes that will concentrate, remove, and
concern in recent years. The escalating processes of industrialization soluble metals can readily penetrate cell membranes (Roane, 1999;
and urbanization have contributed to the significant release of heavy Tiquia-Arashiro, 2018; Jeong et al., 2023). To counteract this, bacteria
metals into aquatic ecosystems (Boening, 2000; Zamora-Ledezma et al., employ immobilization strategies to counteract the toxic effect of
2021; Goswami and Neog, 2023). The release of heavy metals into heavy metals, which includes precipitation, intracellular accumulation,
industrial discharges, urban runoff, and agricultural activities (Tiquia, and Sadler, 1984; Roane, 1999; van Hullebusch et al., 2003; Tiquia-
2010; Oest et al., 2018; Patel et al., 2019; Narwal et al., 2023). These Arashiro, 2018; Vandana et al., 2023). EPSs typically consist of
and Neog, 2023). As heavy metals accumulate in aquatic environments, interactions with cationic metal ions, ultimately leading to the
to aquatic life and endangering the health of humans who rely on these 2019). The effectiveness of EPS-mediated biosorption in efficiently
recreational activities (Tiquia, 2011; Sharma et al., 2023). Additionally, (Shameer, 2016; Vishan et al., 2017; Saba et al., 2019; Sharma and
heavy metal contamination can have far-reaching ecological Saraf, 2023). As a result, biosorption via EPS has garnered substantial
terrestrial ecosystems as well (Ledin, 2000; Ahmad et al., 2021). Among from the ecosystem but are also required to be recovered from every
(Boulanger and Nikolaidis, 2003; Tchounwou et al., 2012; Queiroz et al., interests due to their ecological importance and practical implications.
2021). These heavy metals find their way into the environment through Despite the isolation of diverse bacterial strains, the significance
Neog, 2023). Traditional techniques such as reverse osmosis, ion paramount. This approach is not only environmentally sound but also
efficacy (Volesky, 1990; Qasem et al., 2021). In response, the 2013; Bhatt et al., 2023). In our previous study (Bowman et al., 2018),
employment of microorganisms for heavy metal removal has emerged we isolated Pb-resistant bacterial strains, Klebsiella sp. R3, Klebsiella
as a highly promising alternative. This approach holds advantages by sp. R19, Serratia sp. L2, and Raoultella sp. L30 from sediments of the
the avoidance of sludge disposal requirements (Kim et al., 1996; Bruins Pb2+ from solution and produce a high rate of flocculation activity
et al., 2000; Lakherwal, 2014). (Bowman et al., 2018). Furthermore, these bacterial strains are well
(Tiquia-Arashiro, 2018). The bioremediation of heavy metals can removal of these strains in aqueous multi-metal solutions has not
ions by living biomass, and biosorption, a passive process where metal This study aims to (1) assess the selective metal removal abilities of
cations are adhered to non-living biomass (Razzak et al., 2022; the bacterial strains in the presence of multiple heavy metals (As3+,
Jeyakumari et al., 2023). In the context of bioaccumulation, energy is Pb2+, Cu2+, Mn2+, Zn2+, Cd2+, Cr6+), (2) investigate the interactions
expended for the absorption of metal ions, usually achieved through between these metals during the sorption process, and (3) uncover
in the cell wall or exported metabolites within the external 2. Materials and methods
exchange, complexation, precipitation, reduction, and chelation 2.1. Bacterial strains
(Vishan et al., 2017; Priya et al., 2022; Sreedevi et al., 2022).

Methods (brief)

The bacterial strains used in this study are resistant to Pb and grew of the metals in solution using an atomic absorption spectrometer
As (NaAsO2), Cr (K2Cr2O7), Cd (CdCl2), Cu (CuCl2.2H20), Pb (Pb culture media without cells) was also monitored to confirm that
with metals. Samples were fixed in 2.5% glutaraldehyde in Sorensen mg L−1).
samples were placed on the sample holder (stub) with carbon tape. To = Ni2+ > Cd2+ > Cr6+; for Klebsiella sp. R19, it was Mn2+ > Pb2+ > Zn2+
improve electron conduction, the samples were sputter coated > As3+ > Cu2+ = Ni2+ > Cd2+ > Cr6+; for Serratia sp. L2, it was Mn2+ >
with phosphate buffer saline (pH 6.8). After washing, the samples were solutions, each containing 10 mg L−1 of As3+, Pb2+, Cu2+, Mn2+, Zn2+,
the samples were washed with 0.1 M carbonate buffer and 0.1 M Na2 was more pronounced for Klebsiella sp. R3 and Klebsiella sp. R19

Implications

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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
3171d06	2026-08-02	major	1 section added
bc84bfc	2026-08-02	major	6 sections added; narrative text revised