Direct analysis and identification of the intestinal microflora of shrimps for their geographical traceability mass spectrometry and bacterial library searching.

The expansion of the seafood market has led to an increased probability of food fraud. The development of rapid and reliable traceability methods for aquatic food products is of utmost importance. In this study, direct analysis and identification of the intestinal microbiota of aquatic foods were conducted. The validity of using BacteriaMS database searching for the identification of bacteria was assessed and demonstrated through analyzing prepared bacterial mixtures. We focused on shrimp as a model for aquatic food products and utilized matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to analyze the intestinal microflora of Chinese shrimp () collected from three different aquaculture farms in China. It was found that the most dominant bacteria found in shrimps' intestines could serve as a basis for distinguishing shrimps' geographical origin. The most dominant bacteria in the intestines varied among shrimps from different origins but remained identical for shrimps from the same origin. The reliability of the method in tracing the geographic origin of aquatic products was further validated by analysis of black tiger shrimp () from different origins. The findings show that the utilization of MALDI-TOF MS for the analysis of the microbial community in the intestines of shrimp samples combined with bacterial library searching can offer a rapid, accurate, and feasible method that can be employed for determining shrimps' geographical origin. The present protocol was successfully utilized for the traceability of origins of Chinese shrimp () and black tiger shrimp (). It is promising to extend the present protocol to other aquatic products with regional characteristics to help combat food fraud in the aquatic product market.