The Role of Microbial Mats in the Removal of Hexavalent Chromium and Associated Shifts in Their Bacterial Community Composition

Abstract

Microbial mats are rarely reported for chromium-polluted ecosystems, hence information on their bacterial diversity and role in chromium removal are very scarce. We investigated the role of nine microbial mats, collected from three quarry sumps of chromium mining sites, in the removal of hexavalent chromium [Cr(VI)]. Bacterial diversity in these mats and community shifts after incubation with Cr(VI) have been investigated using MiSeq sequencing. In nature, a chromium content of 1,911 ± 100 mg kg −1 was measured in the microbial mats, constituting the third highest source of environmentally available chromium. The mats were able to remove 1 mg l −1 of Cr(VI) in 7 days under aerobic conditions. MiSeq sequencing of the original mats yielded 46-99% of the sequences affiliated to Proteobacteria, Firmicutes and Actinobacteria. When the mats were incubated with Cr(VI), the bacterial community shifted in the favor of Alphaproteobacteria and Verrucomicrobiae. We conclude that microbial mats in the quarry sumps harbor diverse microorganisms with the ability to remove toxic Cr(VI), hence these mats can be potentially used to remove chromium from polluted waters.

Dietary Fiber Modulates the Fermentation Patterns of Cyanidin-3-O-Glucoside in a Fiber-Type Dependent Manner

“…However, mixing C3G with PEC and BG did significantly increase propionic acid production in the fermentation broth, especially for the CB group. Previous studies have similar results to ours [ 30 , 43 ]. A significant increase in the Bacteroides ( Figure 5 E) from β-glucan fermentation may explain the increase in propionate production [ 57 ].…”

“…This observation could be attributed to the fact that the fermentation of polysaccharides resulted in an acidic environment that was not suitable for the growth of Escherichia–Shigella . Both Bacteroides ( Figure 6 C) and Lactobacillus ( Figure 6 D) can induce an acidic environment [ 43 ], which could explain why the abundance of Escherichia–Shigella in CB and CP groups was lower than that in the other two groups (CF and CA). Lactobacillus species have significant effects on intestinal permeability, inflammation, body weight, and obesity [ 44 , 45 ].…”

Changes in the bacterial rare biosphere after permanent application of composted tannery sludge in a tropical soil

“…Interestingly, we found some specific bacterial genera increasing their abundance at high CTS concentrations, suggesting a high tolerance to contamination of Cr in this soil. For instance, Parviterribacter, Rubrobacter, Gaiella, and Solirubrobacter belong to the Actinobacteria phylum and are recognised as tolerant to contamination by Cr (Abed et al, 2020; Different processes contributed to structuring the dominant and rare components of the bacterial communities. Whereas a combination of processes mediated the assembly of the dominant component of the bacterial community, the structure of the rare biosphere was exclusively driven by homogeneous selection.…”

Insight Into the Molecular Mechanisms Underpinning the Mycoremediation of Multiple Metals by Proteomic Technique

“…These hazardous contaminants are discharged into various water bodies via irrigation during agricultural activities. This results in bioaccumulation of these contaminants that enter the food chain and cause detrimental health ailments, such as cancer in human beings ( Kou et al, 2018 ; Li et al, 2019 ; Abed et al, 2020 ; Chauhan et al, 2021 ; Irawati et al, 2021 ). Thus, these heavy metals are the environmental priority contaminants threatening the environment and therefore must be remediated before discharge into the environment.…”