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Title:	Antibacterial peptide-containing compound derived from palm kernel cake (PKC)
Authors:	Tan Yen Nee (P48942)
Supervisor:	Mohd Khan Ayob, Dr.
Keywords:	Peptide-containing Palm kernel cake (PKC) Oil cake as feed
Issue Date:	20-Feb-2013
Description:	Palm kernel cake (PKC), the co-product from palm kernel oil production has always been used as animal feed, mostly ruminants. PKC could be upgraded into value-added product by widening their usage. In this study, a peptide-containing compound was produced from palm kernel cake (PKC) through extraction with ethanolic alkaline solution (3N NaOH, 20% ethanol, at 80 oC), followed by enzymatic hydrolysis (alcalase, pepsin or trypsin). The compound was found to have inhibition effect against spore-forming bacteria, Bacillus sp. and Clostridium sp. Alcalase-hydrolyzed PKC extract with degree of hydrolysis (DH) 70% showed greater antibacterial effect compared to the other PKC hydrolyzed extract preparations. Response Surface Methodology (RSM) revealed that the pH of hydrolysis medium and PKC substrate concentration significantly (P≤0.05) influence the hydrolysis efficiency of the PKC extract by alcalase. The optimum parameters employed in producing the active compound with DH 70% were 1.68% PKC treated with 1% alcalase (enzyme/substrate concentration) at pH 9.59 and 50 oC. Alcalase-hydrolyzed PKC extract at 70 DH% (AH) and trypsin-hydrolyzed PKC extract at 80 DH% (TH) were chosen for further desalting process by gel filtration chromatography. The desalting process had caused the loss of certain amino acids which may contribute to the antibacterial effect of the compounds although significant (P≤0.05) salt content reduction was achieved. Desalted AH showed greater antibacterial activity than desalted TH. This is probably due to the higher percentage (>90%) of low molecular weight substance (<10 kDa) present in the compound compared to only 38% found in desalted TH as determined using bio-analyzer. Desalted AH was demonstrated to be a peptide-containing complex rather than a pure peptide which constituted of 14.63±0.70% protein, 1.05±0.02% fat and 10.92±0.12% ash. Lauric acid was found present in the compound as proven by ESI-MS and NMR analysis. The presence of peptide was evidenced by FTIR analysis. The compound has low cytotoxicity potential as proven by the low hemolytic activity on human erythrocytes. Less than 50% hemolysis (18.00±0.20% hemolysis) occurred at 1000 μg/ml of desalted AH. Desalted AH and desalted TH which respectively high in lysine [21.38±0.55% (g/100g protein)] and proline [20.20±1.03% (g/100g protein)] were antibacterial mode of action compared. With the existence of lysine and proline, facilitates the attachment of the compounds to the membrane surface of B. cereus. Desalted AH and desalted TH at MIC level, 250 μg/ml and 350 μg/ml respectively have substantially permeabilize the membrane bilayer, trigger efflux of K+, depleting intracellular ATP, and interfering the synthesis of RNA in B. cereus. Desalted AH tends to induce total ATP depletion of B. cereus rather than causing intracellular ATP efflux as shown by desalted TH. Obvious roughening and rupture of cells' surface was observed on desalted AH-treated cells under scanning electron microscope (SEM). Nevertheless, the inhibition effect of both desalted AH and desalted TH is suggested to be more as bacteriostatic rather than bactericidal. This study demonstrated PKC antibacterial compound especially desalted AH is suitable and have the potential of becoming alternative antibacterial/bacteriostatic agent in food or in pharmaceutical industry in the near future.,Ph.D
Pages:	175
Call Number:	SF99.O4.T346 2013
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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