Microbial consortia-mediated arsenic bioremediation in agricultural soils: Current status, challenges, and solutions

Arsenic poisoning in agricultural soil is caused by both natural and man-made processes, and it poses a major risk to crop production and human health. Soil quality, agricultural production, runoff, ingestion, leaching, and absorption by plants are all influenced by these processes. Microbial consortia have become a feasible bioremediation technique in response to the urgent need for appropriate remediation solutions. These diverse microbial populations collaborate to combat arsenic poisoning in soil by facilitating mechanisms including oxidation-reduction, methylation-demethylation, volatilization, immobilization, and arsenic mobilization. The current state, problems, and remedies for employing microbial consortia in arsenic bioremediation in agricultural soils are examined in this review. Among the elements affecting their success include diversity, activity, community organization, and environmental conditions. Also, we emphasize the sensitivity and accuracy limits of existing assessment techniques. While earlier reviews have addressed a variety of arsenic remediation options, this study stands out by concentrating on microbial consortia as a viable strategy for arsenic removal and presents performance evaluation and technical problems. This work gives vital insights for tackling the major issue of arsenic pollution in agricultural soils by explaining the potential methods and components involved in microbial consortium-mediated arsenic bioremediation.

Leveraging arsenic resistant plant growth-promoting rhizobacteria for arsenic abatement in crops

Arsenic is a toxic metalloid categorized under class 1 carcinogen and is detrimental to both plants and animals. Agricultural land in several countries is contaminated with arsenic, resulting in its accumulation in food grains. Increasing global food demand has made it essential to explore neglected lands like arsenic-contaminated lands for crop production. This has posed a severe threat to both food safety and security. Exploration of arsenic-resistant plant growth-promoting rhizobacteria (PGPR) is an environment-friendly approach that holds promise for both plant growth promotion and arsenic amelioration in food grains. However, their real-time performance is dependent upon several biotic and abiotic factors. Therefore, a detailed analysis of associated mechanisms and constraints becomes inevitable to explore the full potential of available arsenic-resistant PGPR germplasm. Authors in this review have highlighted the role and constraints of arsenic-resistant PGPR in reducing the arsenic toxicity in food crops, besides providing the details of arsenic transport in food grains.

Anaerobic arsenite oxidation with an electrode serving as the sole electron acceptor: a novel approach to the bioremediation of arsenic-polluted groundwater

Arsenic contamination of soil and groundwater is a serious problem worldwide. Here we show that anaerobic oxidation of As(III) to As(V), a form which is more extensively and stably adsorbed onto metal-oxides, can be achieved by using a polarized (+497 mV vs. SHE) graphite anode serving as terminal electron acceptor in the microbial metabolism. The characterization of the microbial populations at the electrode, by using in situ detection methods, revealed the predominance of gammaproteobacteria. In principle, the proposed bioelectrochemical oxidation process would make it possible to provide As(III)-oxidizing microorganisms with a virtually unlimited, low-cost and low-maintenance electron acceptor as well as with a physical support for microbial attachment.