Abstract:In this study, Vibrio parahaemolyticus reference materials without matrix were prepared and detected. The standard strain CMCC20030 was identified by MALDI-TOF MS, biochemical reaction and 16S RNA gene sequencing. The Vibrio parahaemolyticus samples (800) with 103 CFU/sample (20 μL) were prepared by freeze-drying technology. 20 samples were selected randomly for uniformity test. The samples were stored at 25 ℃ and 37 ℃ for 1, 3, 5 and 7 days respectively for transportation stability test, stored at 4 ℃ for 7, 14 and 28 days respectively for short-term preservation stability test, and stored at -20 ℃ for 14, 28 and 60 days respectively for preservation stability test. Five laboratories were organized for collaborative calibration. 20 food products were chosen as the substrate, the applicability was tested according to GB4789.7-2013. The strain CMCC20030 was identified as Vibrio parahaemolyticus by MALDI-TOF MS, biochemical reaction and 16s RNA gene sequencing. The uniformity result was Fsample=1.930< FINV (0.05, 19, 20) by one-way anova. The samples were still 103 CFU/sample when storing 60 d at -20 ℃, 28 d at 4 ℃, 3 d at 37 ℃ and 7 d at 25 ℃. All the results of 5 laboratories were 103 CFU/sample. All 20 samples presented Vibrio parahaemolyticus positively when adding any substrate, only 20 substrates presented negatively. The Vibrio parahaemolyticus sample without matrix meets relevant standards of uniformity, stability, collaborative calibration and applicability, can be applied to different study as reference material according to different purposes.
