Title : Antibacterial activity of novel peptides purified from buffalo and bovine casein hydrolysates by proteases
Abstract:
The objective of this study was to investigate the antibacterial characteristics of buffalo casein (CB) and bovine casein (CN) hydrolysates by proteases (papain, pepsin, alcalase and trypsin) and its fractions against Gram negative (Escherichia coli, Salmonella typhimurium) and Gram-positive (Staphylococcus aureus, Bacillus subtilis). The casein hydrolysates were separated using ultrafiltration (UF) and further purified by RP-HPLC. The fractions produced higher antibacterial activities were identified for their peptides using LC MS/MS. The results demonstrated that pepsin hydrolysate from concentration of 6 mg/mL to 10 mg/mL exhibited highest antibacterial activities against all pathogenic bacteria with exception for Salmonella typhimurium that was the least affected. The fraction with a low molecular weight (<1 kDa) of peptides demonstrated the highest inhibition of growth than other fractions. Moreover, fraction (<1 kDa) at concentration of 1mg/mL was the most effective as an inhibitor against Bacillus subtilis; whereas Escherichia coli, Salmonella typhimurium and Staphylococcus aureus were at concentration of 4 mg/mL in both CN and CB. Among 40 fractions of RP-HPLC purified, fraction 1, 14 and 15 and fraction 2 and 4 showed higher antibacterial activity than the other fractions for CB and CN respectively. Consequently, the novel antibacterial peptides identified by LC MS/MS were LRG, DKT, RLMF, SKK, LRF, MRSPGANH and EMEL in CB. The results could provide novel antibacterial peptides from CB that can find a potential natural food preservative utilization in the food industry as a natural bio-preservative and nutraceuticals, and pharmaceuticals.
