## 3 Results and Discussion
### Analysis of the Antibacterial Activity of GV Extracts  
To investigate the antibacterial activity of the GV extracts against foodborne bacteria, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the GV extracts against the six bacteria were determined (Table 6). The MIC values for GV extracts ranged from 0 to 3 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\) against these bacteria. Notably, the GVE exhibited the highest MIC values (0.06-0.3 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\)) compared to the other extracts. The MIC values for the GVM ranged from 1 to 3 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\). In contrast, GVW was not effective against foodborne bacteria, suggesting that it possessed the lowest antibacterial activity among the extracts. The GV extracts displayed MBC values ranging from 1 to 6.0 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\) against the six foodborne bacteria. The GVE had MBC values in the range of 0.1-0.5 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\), showcasing the highest antibacterial activity, followed by the GVM and GVW. Specifically, the GVE and GVM demonstrated the most potent antibacterial activity against \(L\). _monocytogenes_ (MBC values = 0.125 and 2.67 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\), respectively). Polysaccharides, such as alginic acid, carrageenan, and laminarin, serve as protective agents against pathogens and promote the accumulation of proteins or compounds with antimicrobial properties [93]. [PERSON] et al. [94] reported that the yield of bioactive substances from seaweeds is influenced by the extraction solvent. Hydrophilic solvents, such as methanol, ethanol, and acetone, exhibit superior antimicrobial activity compared to hydrophobic solvents. [PERSON] et al. [95] noted that the methanol fraction of Cyan bacteria _Spirulina platensis_ showed high polyphenol content and antimicrobial activity against \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Foodborne Bacteria**} & \multicolumn{2}{c}{**GVE**} & \multicolumn{2}{c}{**GVM**} & \multicolumn{2}{c}{**GVM**} \\ \cline{2-7}  & **MIC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** & **MBC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** & **MIC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** & **MBC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** & **MIC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** & **MBC (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro L}\))** \\ \hline _B. cereus_ & 0.25 & 0.5 & 2.67 & 5.31 & - & - \\ _S. aureus_ & 0.125 & 0.25 & 2.67 & 5.31 & - & - \\ _L. monocytogenes_ & 0.0625 & 0.125 & 1.33 & 2.67 & - & - \\ _E. coli_ & 0.125 & 0.25 & 1.33 & 2.67 & - & - \\ _S. typhimurium_ & 0.125 & 0.25 & 2.67 & 5.31 & - & - \\ _V. parahaemolyticus_ & 0.125 & 0.25 & 1.33 & 2.67 & - & - \\ \hline \end{tabular}
\end{table} 
Table 6: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of _Gracilaria vertracosa_ extract against foodborne bacteria. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Compound Contents (\(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{\SIUnitSymbolMicro g}\))** & **GVE** & **GVM** & **GVM** \\ \hline
4-hydroxy benzoic acid & ND & ND & 1.91 \(\pm\) 0.01 \\ Naringenin & 1.33 \(\pm\) 0.01 & ND & ND \\ Naringin & 666.88 \(\pm\) 4.07 & ND & ND \\ GVE, _G. vertracosa_ ethanol extract; GVM, _G. vertracosa_ methanol extract; GVW, _G. vertracosa_ water extract; ND, not detected. E. coli_ and _S. aureus_ and that the polyphenols from the methanol fraction interacted with each other, resulting in strong antimicrobial activity of the methanol extract, even at low concentrations. [PERSON] [96] explored the antibacterial activity of GV against _E. coli_ and _S. typhimurium_ based on the extraction solvent and administration time.