Powerful Antibacterial Peptides from Egg Albumin Hydrolysates

Abstract

Native egg albumin (NEA) was isolated from hen eggs and hydrolyzed by pepsin to produce hydrolyzed egg albumin (HEA). HEA was chemically characterized and screened for its antibacterial activity against 10 pathogenic bacteria (6 Gram (+) and 4 Gram (−)). The SDS-PAGE pattern of NEA showed molecular weights of hen egg albumin subunits ranging from 30 to 180 kDa. The highest intensive bands appeared at a molecular mass of about 50 and 97 kDa. Ultra-performance liquid chromatography (UPLC) of the peptic HEA revealed 44 peptides, 17 of them were dipeptides, and the other 27 fractions corresponded to bigger peptides (3–9 amino acids). The dipeptides and big peptides represented 26% and 74% of the total hydrolysate, respectively. The MIC of HEA was about 100 μg/L for Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella typhimurium, Streptococcus pyogenes, and Klebsiella oxytoca and 150 μg/L for Pseudomonas aeruginosa, Bacillus subtilis, and Listeria ivanovii and 200 μg/L for Escherichia coli. L. monocytogenes was the most sensitive organism to HEA. Mixtures of HEA with antibiotics showed more significant antibacterial activity than individually using them. Transmission electron microscopy (TEM) revealed various signs of cellular deformation in the protein-treated bacteria. HEA may electrostatically and hydrophobically interact with the cell wall and cell membrane of the susceptible bacteria, engendering large pores and pore channels leading to cell wall and cell membrane disintegration. Higher cell permeability may, thus, occur, leading to cell emptiness, lysis, and finally death. Alternatively, no toxicity signs appeared when HEA was administrated to Wistar Albino rats as one single dose (2000, 5000 mg/kg body weight) or repeated daily dose (500 and 2500 mg/kg body weight/day) for 28 days to disclose the possible toxicity hazards. HEA did not produce any death.

Antibacterial Peptides Produced by Alcalase from Cowpea Seed Proteins

“…AMPs are promising new antibacterial agents due to their killing mechanism via interaction with bacterial cell walls and membranes [19,41].They could be generated by different methods, such as chemical modification [23], microbial fermentation [42] and enzymatic proteolysis [29]. Alcalase has been used to generate biologically active peptides from different sources, such as barbel muscle protein [40], goat whey protein [27], sorghum protein [43], chickpea protein [44], canola protein [45], and egg [46],that cleaves the high molecular weight, releasing more active subunits with smaller molecular sizesand with a hydrophobic nature that showed greater antimicrobial activity [41]. This optimization produces effective bactericidal peptides that may be identified as potential antimicrobials [41,47,48].…”

“…Alcalase has been used to generate biologically active peptides from different sources, such as barbel muscle protein [40], goat whey protein [27], sorghum protein [43], chickpea protein [44], canola protein [45], and egg [46],that cleaves the high molecular weight, releasing more active subunits with smaller molecular sizesand with a hydrophobic nature that showed greater antimicrobial activity [41]. This optimization produces effective bactericidal peptides that may be identified as potential antimicrobials [41,47,48].…”

“…This is probably due to the liberation of some antibacterial peptides upon Alcalase hydrolysis of the cowpea seed proteins [28]. The interaction of antimicrobial peptides with bacterial cells is dependent on their amino acid composition and their methyl groups that process cationic charges which could connect to cell membrane bilayers, and in turn cause pore formation [41]. This mechanism might happen through electrostatic binding between the positively charged parts of the cationic proteins and the negatively charged layers of the cell membrane rising from teichoic acid and phospholipid components causing cell degeneration, and in turn cell lysis or destructionleading to leakage of cell electrolytes [51].…”

Health Aspects, Growth Performance, and Meat Quality of Rabbits Receiving Diets Supplemented with Lettuce Fertilized with Whey Protein Hydrolysate Substituting Nitrate

“…WPH may be a good substitute of nitrate since meats from rabbits administered with WPH-fortified lettuce juice (group IV) achieved the second-highest rating, with lower APC and pH values than that of the negative control and the rabbits served nonfortified lettuce juice. These changes may be associated with powerful bioactive antimicrobial peptides of whey hydrolysates, which possibly triggered in the rabbit intestine by either hydrolytic digestive enzymes, proteolytic microorganisms, and/or the action of plant or microbial proteases [47][48][49][50][51]. Applying bioactive proteins and peptides was shown to have antibacterial and antioxidant benefits [52][53][54][55], for example, by increasing dietary WPC in broiler, resulting in a reduction in malondialdehyde (MDA) values and an improvement in glutathione peroxidase, glutathione-S-transferase, catalase, and superoxide dismutase in meat [56].…”

Foliar Spray with Pepsin-and Papain-Whey Protein Hydrolysates Promotes the Productivity of Pea Plants Cultivated in Clay Loam Soil

“…An aliquot of 10 µL of the final peptide solution was injected into the chromatograph and peptides were separated on a XEVO TQD triple quadruple instrument Waters Corporation, Milford, MA01757 U.S.A, mass spectrometer. Column: ACQUITY UPLC-BEH C18 1.7 µm–2.1 × 50 mm Column with flow rate: 0.2 mL/min using solvent system: consisted of (A) water containing 0.1% formic acid (B) Actonitrile containing 0.1 % formic acid [ 47 ].…”