Bacillus cereus is a pathogenic bacterium that causes food contamination, resulting in food poisoning such as diarrhea and emesis. Therefore, it is crucial to develop effective strategies to control this bacterium. In this study, we isolated and characterized a novel B. cereus phage, named DZ1. Morphological and genomic analyses revealed that phage DZ1 is a new species belonging to the Andromedavirus genus. Phage DZ1 was tolerant to a wide range of pH values (5–9), temperatures (4–55 ℃), and high concentrations of NaCl solution (1000 mM). B. cereus with 21 different sequence types (STs) can be lysed by phage DZ1. Importantly, phage DZ1 inhibited B. cereus growth in spiked rice substrates or milk up to 36 and 72 h, respectively, with suppression of 3 log. Therefore, phage DZ1 is a useful biocontrol agent for the control of B. cereus in the food industry.
Lei Wang,Li Hao,Wuzhen Qi,Xiaoting Huo,Li Xue,Yuanjie Liu,Qiang Zhang,Jianhan Lin
Salmonella is the leading factor for microbial food poisoning. In this study, a facile pressure biosensor was developed for rapid and sensitive detection of Salmonella using magnetic nanobeads (MNBs) to separate target bacteria, platinum nanoparticle loaded manganese dioxide nanoflowers ( [email protected] 2 NFs) to amplify detection signal, and a thin-film piezoresistor based pressure detector to monitor pressure change. First, the capture antibodies (CAbs) modified MNBs were used to specifically separate Salmonella from sample to form MNB-CAb- Salmonella complexes (magnetic bacteria). Then, the detection antibodies (DAbs) modified [email protected] 2 NFs were used for labelling magnetic bacteria to form MNB-CAb- Salmonella [email protected] 2 NF complexes (nanoflower bacteria). After nanoflower bacteria were resuspended with H 2 O 2 in a sealed centrifuge tube, H 2 O 2 was catalyzed by [email protected] 2 NFs to produce O 2 , resulting in the increase on pressure. Finally, the pressure increase was real-timely monitored by piezoresistor based pressure detector and transferred to smartphone App via Bluetooth for analysis and determination of Salmonella . This biosensor could quantitatively detect Salmonella from 1.5 × 10 1 to 1.5 × 10 5 CFU/mL in 1.5 h with low detection limit of 13 CFU/mL. The [email protected] 2 NFs with high loading capacity of platinum nanoparticles were demonstrated as dual mimic enzymatic catalyst of H 2 O 2 to greatly enhance the sensitivity. More importantly, it is the first time to combine a thin-film piezoresistor with a smartphone App for realtime monitoring of the pressure change resulting from the mimic enzymatic catalysis of H 2 O 2 into O 2 by the [email protected] 2 NFs on the target bacteria to determine pathogenic bacteria in food samples.
危险品化学品经营许可证（带存储）