Natural Microbial Reactor-Based Sensing Platform for Highly Sensitive Detection of Inorganic Arsenic in Rice Grains

Abstract

Rice is a major dietary source of inorganic arsenic (iAs), a highly toxic arsenical that accumulates in rice and poses health risks to rice-based populations. However, the availability of detection methods for iAs in rice grains is limited. In this study, we developed a novel approach utilizing a natural bacterial biosensor, Escherichia coli AW3110 (pBB-ArarsR-mCherry), in conjunction with amylase hydrolysis for efficient extraction, enabling high-throughput and quantitative detection of iAs in rice grains. The biosensor exhibits high specificity for arsenic and distinguishes between arsenite [As­(III)] and arsenate [As­(V)] by modulating the concentration of PO4 3– in the detection system. We determined the iAs concentrations in 19 rice grain samples with varying total As concentrations and compared our method with the standard technique of microwave digestion coupled with HPLC-ICP-MS. Both methods exhibited comparable results, without no significant bias in the concentrations of As­(III) and As­(V). The whole-cell biosensor demonstrated excellent reproducibility and a high signal-to-noise ratio, achieving a limit of detection of 16 μg kg–1 [As­(III)] and 29 μg kg–1 [As­(V)]. These values are considerably lower than the maximum allowable level (100 μg kg–1) for infant rice supplements established by the European Union. Our straightforward sensing strategy presents a promising tool for detecting iAs in other food samples.

Ultrasensitive Electrochemiluminescence Sensor Utilizing Aggregation-Induced Emission Active Probe for Accurate Arsenite Quantification in Rice Grains

“…Compared with the high temperature and strong acid environment of microwave digestion, enzymatic hydrolysis possesses obvious advantages in maintaining the stability of As species, making it more suitable for biosensing analysis. Our previous work has also demonstrated that the enzymatic hydrolysis method can better prevent As­(III) oxidation under relative mild conditions . Comparing with the commonly used microwave digestion method, the arsenic concentrations obtained by the two methods did not deviate significantly.…”

“…Our previous work has also demonstrated that the enzymatic hydrolysis method can better prevent As(III) oxidation under relative mild conditions. 33 Comparing with the commonly used microwave digestion method, the arsenic concentrations obtained by the two methods did not deviate significantly. We investigated samples of rice from different regions in China, including Dongbei, Guangxi, Hubei, Hunan, and Jiangsu.…”

“…First, the rice grains were ground into powder; 1 g of the rice powder was reacted with 9 mL of 20 mM MES buffer solution (20 mM, pH 6.5) at 85 °C for 30 min. Then, 0.04 g of amylase (3700 U g –1 ) was added and incubated at 60 °C for 2 h, followed by ultrasonic (30 min) . The obtained mixture was diluted and centrifuged at 10,000 rpm for 10 min.…”

“…Then, 0.04 g of amylase (3700 U g −1 ) was added and incubated at 60 °C for 2 h, followed by ultrasonic (30 min). 33 The obtained mixture was diluted and centrifuged at 10,000 rpm for 10 min. Finally, the resulting supernatants were filtered with a 0.22 μm filter membrane.…”

Atomic spectrometry update: review of advances in elemental speciation

“…A natural bacterial biosensor utilising Escherichia coli AW3110 (pBB- Arars R- m Cherry), in conjunction with amylase hydrolysis for extraction has been used for the quantitative detection of iAs in rice grains. 58 The biosensor exhibited high specificity for As and it was possible to distinguished between As III and As V by modulating the concentration of PO 4 3− in the detection system. The iAs concentrations were determined in 19 rice grain samples with varying total As concentrations and compared with a reference technique using enzymatic hydrolysis and microwave digestion coupled with HPLC-ICP-MS.…”