Bimetallic metal-organic framework-mediated aptasensing platform for rapid detection of Bacillus cereus in brewery wastewater.

Bacillus cereus is commonly present in brewing fermentation systems and their wastewater. The potential threats to food safety and environmental health posed by the spores of this bacterium and its toxin-producing capacity require the development of rapid, sensitive detection methods suitable for complex matrices. To address the tedious operation and high cost of current detection methods, we describe a label-free colorimetric aptamer biosensing platform based on an aptamer-regulated bimetallic zirconium-cobalt metal-organic framework (ZrCo-MOF). This platform enables highly sensitive detection of B. cereus in brewery wastewater. The bimetallic ZrCo-MOF, featuring Zr(IV) and Co(II) as metal nodes and 1,3,5-benzenetricarboxylic acid as an organic ligand, exhibits relatively high peroxidase-like activity. It functions as a catalyst for an H2O2-mediated chromatic reaction, generating a distinctive chromatic signal. The aptamer binds to the MOF surface via Zr-O-P coordination, thereby inhibiting enzyme activity. When target bacteria are present, the aptamer binds more strongly to B. cereus and detaches from the MOF surface. This restores enzymatic activity and triggers a colour change. The method is completed within 1.5 h, maintains satisfactory linearity over the range of 10-107 CFU/mL, and achieves a detection limit of 5 CFU/mL. We applied this method to spiked brewery wastewater samples and validated its suitability. The results suggest that the platform is capable of detecting B. cereus and can be applied to rapid screening of brewery wastewater in food-related settings.