Abstract
Food matrices such as phytic acid, starch, and proteins can chelate heavy metals, acting as stabilizers that significantly hinder accurately detecting heavy metal contamination. This study proposes a biological digestion strategy to overcome such interference. The gene sequences for phytase (appA) from Escherichia coli (E. coli), α-amylase (amyA) from Escherichia coli (E. coli), and protease (AO090120000474) from Aspergillus oryzae were identified via bioinformatics screening. Whole-cell biosensors were then developed to simultaneously detect mercury ions (Hg(2+)) and digest phytate, starch, and proteins. In the presence of 100 μM Hg(2+), biosensor responses improved by 1.43-, 1.38-, and 1.11-fold, respectively. A "heavy metal pollutant bio-digestion pathway" was constructed by integrating genes for synthesizing phytic acid, starch, and protein with those for Hg(2+) detection. In the presence of 100 μM Hg(2+), the detection effect was improved by 1.36-fold. The detection limit of the BαAP whole-cell biosensor was 0.082 μM, while the limit of quantitation was 0.272 μM. The study effectively addresses the limitations of biosensor performance in real sample detection.