Role of microbial iron reduction in arsenic metabolism from soil particle size fractions in simulated human gastrointestinal tract. (April 2023)

• Record Type: Journal Article
• Authors: Yin, Naiyi; Chang, Xuhui; Xiao, Peng; Zhou, Yi; Liu, Xiaotong; Xiong, Shimao; Wang, Pengfei; Cai, Xiaolin; Sun, Guoxin; Cui, Yanshan; Hu, Zhengyi
• Is Part Of: Environment international. Volume 174(2023)
• Publication Date: 2023-04
• Subjects: Arsenic -- Iron -- Gut microbiomta -- Metabolism -- Speciation analysis -- Simulator of the Human Intestinal Microbial Ecosystem; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2023.107911
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: Fe reduction coupled with soil particle size control As metabolism by gut microbiota. A high degree of As reduction and methylation up to 53.4 and 0.074 μg/(log CFU/mL)/hr. Increased As methylation with increasing soil organic matter and decreasing pore size. Higher As bioaccessibility of colon phase from Fe(III) oxide reductive dissolution. Arsenic reduction mediated by gut microbiota carrying arrA and arsC genes. Abstract: Gut microbiota provides protection against arsenic (As) induced toxicity, and As metabolism is considered an important part of risk assessment associated with soil As exposures. However, little is known about microbial iron(III) reduction and its role in metabolism of soil-bound As in the human gut. Here, we determined the dissolution and transformation of As and Fe from incidental ingestion of contaminated soils as a function of particle size (<250 μm, 100–250 μm, 50–100 μm and < 50 μm). Colon incubation with human gut microbiota yielded a high degree of As reduction and methylation of up to 53.4 and 0.074 μg/(log CFU/mL)/hr, respectively; methylation percentage increased with increasing soil organic matter and decreasing soil pore size. We also found significant microbial Fe(III) reduction and high levels of Fe(II) (48 %−100 % of total soluble Fe) may promote the capacity of As methylation. Although no statistical change in Fe phases was observed with low Fe dissolution and high molar Fe/As ratios, higher As bioaccessibility of colon phase (avg. 29.4 %) was mainly contributed from reductive dissolution of As(V)-bearing Fe(III) (oxy)hydroxides. Our results suggest that As mobility and biotransformation by human gut microbiota (carrying arrA and arsC genes) are strongly controlled by microbial Fe(III) reduction coupled with soil particle size. This will expand our knowledge on oral bioavailability of soil As and health risks from exposure to contaminated soils.