1- Department of Food Science and Technology, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran
2- Department of Food Science and Technology, Faculty of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran 14515.775, Iran.
3- Department of Biochemistry, University of Kharazmi, Tehran, Iran
4- Department of Science, Faculty of Biology, Islamic Azad University, Tehran Central Branch, Iran
Abstract: (7364 Views)
The presence of antibacterial activity in bovine β-lactoglobulin and in α-lactalbumin hydrolysates was investigated. The Plasmin-Digest of β-lactoglobulin (PDβ) and of α-lactalbumin (PDα) were fractionated, using reversed phase high performance liquid chromatography. The antibacterial activity of β-lactoglobulin, α-lactalbumin, nisin, plasmin, PDβ and PDα were in vitro tested against pathogenic (Escherichia coli and Staphylococcus aureus) and probiotic (Lactobacillus casei and Lactobacillus acidophilus) bacteria. Although α-lactalbumin, β-lactoglobulin and plasmin exhibited no antibacterial activity, PDβ, PDα and nisin revealed antibacterial activity against the bacteria tested. The Minimum Inhibitory Concentration (MIC) of these compounds was determined for the bacteria cultures. Similar to nisin, the MIC of PDβ and of PDα against Gram-positive bacteria was recorded as considerably lower than the MICs against Gram-negative bacteria. The study also evaluated the effect of PDβ, PDα and nisin on the growth curves and on the plate count confirmations of the target bacteria. The results revealed that nisin, PDβ and PDα have inhibitory effects on the lag phase, maximum OD620 and on plate count confirmation of the bacteria tested. The maximum inhibitory effect of these compounds was created during the log phase. Their inhibitory effects depended upon their concentrations, higher concentration causing stronger antibacterial activity. The PDβ and PDα proved more active against Gram-negative bacteria than did nisin, but nisin revealed substantial inhibitory activity against Gram-positive bacteria.
Article Type:
Research Paper |
Subject:
Food Science and Technology Received: 2013/08/21 | Accepted: 2014/03/15 | Published: 2014/11/1