Abstract
The bacterial profiles of 63 grasshopper sub shrimp paste samples collected from seven typical regions around the Bohai Sea were investigated by high-throughput sequencing. Tetragenococcus muriaticus was found to be the prevailing species present in all the samples, and the presence of T. muriaticus also weakly correlated with the histamine content in the samples. Six T. muriaticus strains with low biogenic amine (BA)-producing ability and deficient in histamine production were identified and subjected to safety assessment. All six strains displayed weak resistance to fifteen known antibiotics as based on the Enterococcus breakpoint values. None of the strains exhibited hemolytic activity or biofilm formation. All strains exhibited were able to grow on MRS agar containing 21% NaCl and expressed amine oxidase and strain-specific proteases and lipases. Most of the strains exhibited acid production at 18% NaCl. Moreover, three of the strains (designated as SG, TS, and QH) with histamine degradation ability were inoculated into separate shrimp paste samples to determine their effect on BA accumulation. The results indicated that the addition of T. muriaticus to shrimp pastes not only led to a significant reduction of BA content in the pastes but also improved the flavor of the pastes. Consequently, these strains may be used as potential candidates for controlling the content of histamine in fermented foods.
Highlights
Grasshopper sub shrimp paste is a famous traditional fermented aquatic product in China
Based on the 16S rRNA gene sequence, T. muriaticus was found to be the predominant species in all the grasshopper sub shrimp paste samples and the abundance was high in the Rongcheng, Panjin and Dalian samples (Figure 1B), representing up to 61.57, 49.84, and 26.09%, respectively
Histamine was found in all the grasshopper sub shrimp paste samples (Figure 2B), and the total biogenic amine (BA) content varied among the grasshopper sub shrimp paste samples
Summary
Grasshopper sub shrimp paste is a famous traditional fermented aquatic product in China. Grasshopper sub shrimps grow in water bordering the junction of seawater and freshwater. Grasshopper sub shrimp paste factories in China are located around the Bohai Sea. Potential Application of Tetragenococcus muriaticus (Sang et al, 2020a). Due to its unique flavor and excellent nutritional value (Lv et al, 2020; Sang et al, 2020b), grasshopper sub shrimp paste is popular in China. The process of natural fermentation involved in the typical production of grasshopper sub shrimp paste has made the process susceptible to contamination by microbes from the environment, making the process less hygienic. No control measures are implemented in the fermentation process, and this can sometimes result in a lack of quality and safety control, thereby affecting both the quality and safety of the fermented food, such as shrimp paste
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