## 4 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**RT (min)**} & \multirow{2}{*}{**Compound Name**} & \multicolumn{2}{c}{**Relative Percentage (\%)**} \\ \cline{3-4}  & & & **Control** & **Test** \\ \hline \multicolumn{4}{c}{Ketones} \\ F1 & 25.76 & Thebacon & ND & 0.07 \\  & & Alcohols & \\ G1 & 1.40 & Cyclobutanol & ND & 1.62 \\ G2 & 51.51 & trans-Farnesol & ND & 0.18 \\  & & Other compounds & \\ H1 & 1.42 & 2-Propanamine & 3.82 & 0.59 \\ H2 & 1.61 & Octodrine & 3.20 & ND \\ H3 & 3.78 & 1,2,4-trimethyl-Piperazine & 0.17 & ND \\ H4 & 49.20 & 4H-1-Benzopyran-2-carbonyl chloride, 4-oxo- & 0.04 & ND \\ H5 & 25.76 & 2-Chloro-4-(4-methoxyphenyl))-6-(4-nitrophenyl)pyrimidine & 0.08 & ND \\ H6 & 3.75 & 1,3,3-Trimethyl-diazirdine & ND & 0.07 \\ H7 & 29.84 & 1-Ethoxy-2-methyl-benzene & ND & 0.06 \\ H8 & 47.68 & 5-Fluoroorotyl-N, N-dimethylhydrazide & ND & 0.01 \\ H9 & 52.08 & 1H-Indole, 2-(1,1-dimethyl-2-propyl)-6-(3-methyl-2-butenyl)- & ND & 0.01 \\ \hline \hline \end{tabular}  
* ND: Not detected. RT: Retention time in the capillary column. Control and Test represent shrimp paste fermented without/with starter culture for 35 days, respectively.  
\end{table} 
Table 2: _Cont._(PUT) and cadaverine (CAD) have far less toxicity, their interactions with amine oxidases may slow down the metabolism and increase the toxicity of histamine [31]. Controlling their content in food is therefore crucial for improving food safety. In our previous study, _T. muriaticus_ TS showed histamine degradation of 12.60% in vitro. In this study, the histamine content decreased by 22.81% with the starter culture inoculation. A previous study has found that when the _Tetragenococcus halophilus_ strain MJ4 was inoculated into fermented shrimp paste, the formation of cadaverine during the fermentation was repressed [20]. Our study demonstrated that _T. muriaticus_ could enhance the food safety of shrimp paste by lowering the content of BA content produced during fermentation. LAB starters have been reported to inhibit the growth of bacteria with high BA-producing activities such as strains of enterococci, lactobacilli, streptococci, and lactococci [7]. Therefore, _T. muriaticus_ might suppress the development of other LAB, therefore reducing the BA accumulation in the grasshopper sub shrimp paste. The primary mechanisms for the synthesis of BAs in fermented foods are microbial amino-acid decarboxylation or amination and transamination of aldehydes and ketones. Therefore, correlations between bacterial genera and the three BAs were conducted. According to the results shown in the Pearson correlation heatmap, _T. muriaticus_ could affect the correlation between the dominant bacterial genera and BAs (Figure 4D,E). _Tetragenococcus_ was a dominating bacterium with a very high abundance in shrimp paste samples (Figure 1A), and the findings revealed that it positively correlated with BAs in the control group while negatively correlated with BAs in the test group. According to a previously published paper, _Tetragenococcus_ was a dominant bacterium and positively correlated with BAs in fermented shrimp paste [23]. On the contrary, in our study, _Tetragenococcus_ was negatively correlated with BAs in the test group. BA-producing capacity has been reported to be a strain-specific characteristic [5], and the _T. muriaticus_ strain used in our work has been proven to suppress the accumulation of BAs in both vitro and grasshopper sub shrimp paste [23]. In the test group, _T. muriaticus_ TS with BA-reducing ability grew rapidly and became the dominant strain, therefore the correlation between _Tetragenococcus_ and BAs became inversely correlated. Moreover, although _Marinilactobacillus_ was positively correlated with the three BAs in the test group, its abundance fell dramatically after the inoculation of the starter culture (Figure 1A). The impacts of starter culture on the physicochemical quality of shrimp paste were also studied.