Protease Hydrolysates of Filefish (Thamnaconus modestus) Byproducts Effectively Inhibit Foodborne Pathogens

In this study, novel antimicrobial peptides had been derived by enzymatic hydrolysis of filefish (Thamnaconus modestus) byproduct (HFBP). Different proteases, (papain [P], trypsin [T], neutrase [N], pepsin [PE], and the mixture I [PN] and mixture II [PT]) and different hydrolysis time (60, 120, 180, and 240 min), have been used to generate peptides with different lengths and amino acid sequences. The antimicrobial properties of HFBPs were tested, against Gram-positive and Gram-negative strains, using disc diffusion method. HFBP prepared after 120 min of the enzymatic hydrolysis by trypsin (HFBP-T) exhibited greatest antibacterial activities. Bacillus cereus 10451 (BC) and Salmonella enteritidis 10982 (SE) strains were most sensitive to HFBP-T with an inhibitory zone of 24.68 and 29.67 mm diameter and minimum inhibitory concentration of 1.25 and 2.5 mg/mL, respectively. Moreover, the antimicrobial activities of tested HFBPs increased significantly at low pH and temperature. The amino acid analysis showed that HFBP-T protein hydrolysate is high in an amino acid of proline, which probably contributes to the antimicrobial activity. The results obtained from scanning electron microscopy suggested that HFBPs might kill bacteria by acting on the cell wall of bacteria. Conclusively, the HFBP derived from filefish byproduct with biological activates is an interesting alternative to the use of waste from the fishing industry as natural antimicrobials in food stuff.