Antibacterial Peptides, Probiotic Properties and Biopreservative Efficacy of Native Bacillus Species Isolated from Diffe
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Antibacterial Peptides, Probiotic Properties and Biopreservative Efficacy of Native Bacillus Species Isolated from Different Food Sources Vadakedath Nithya • Prakash M. Halami
Ó Springer Science+Business Media New York 2012
Abstract In this study, we evaluated the occurrence of antibacterial peptide (ABP)-producing Bacillus spp. in fermented foods. Among 78 isolated cultures, 25 potential ABP-producing stains were selected and differentiated genotypically and phenotypically. The 16S rRNA gene sequence homology, in combination with morphological, physiological and biochemical characteristics, was used for the identification of the isolates. The isolates exhibited inhibitory activity against both Gram-positive and Gramnegative food-borne pathogens. The antibacterial compounds produced by these cultures were proteinaceous in nature, with molecular weight falling in the range of 3–6.5 kDa. The ABP present in the cell-free supernatant of B. subtilis Ec1 and B. licheniformis Me1 exhibited the highest titre of activity (3,400 AU/ml) and wide range of pH (4–10) and temperature (40–100 °C) stability. The strain Ec1 was found to be exhibiting some in vitro probiotic properties, such as acid and bile tolerance, bile salt hydrolase activity and hydrophobicity towards hydrocarbons. The viable counts of Listeria monocytogenes Scott A in pasteurized milk samples containing ABP of Ec1 were lower than those observed in controls without ABP. The ABP-coated packaging films exhibited antimicrobial activity against the pathogens, indicating the application of ABP from Bacillus spp. in antimicrobial packing materials. These observations increase the likelihood of potential use
Electronic supplementary material The online version of this article (doi:10.1007/s12602-012-9115-x) contains supplementary material, which is available to authorized users. V. Nithya P. M. Halami (&) Department of Food Microbiology, CSIR-Central Food Technological Research Institute, Mysore 570 020, India e-mail: [email protected]
of the isolated Bacillus spp. or their ABP for application in food biopreservation and as probiotics. Keywords Bacillus Antibacterial peptide RAPD-PCR 16S rRNA gene Fermented food
Introduction Antibacterial peptides (ABPs) are produced by bacteria as a part of its defence mechanism. The ABPs are considered ideal candidates for food preservation because of their antagonistic activity against specific pathogens, as well as their potential absence of harmful effects on humans [2, 11]. During the past years, antimicrobial compounds produced by lactic acid bacteria (LAB) have been the subject of intensive study because of their potential use as biopreservatives in the food industry [16]. Apart from LAB, Bacillus genus also produces large number of ABPs which makes it an interesting genus to investigate [51]. Reports on application of Bacillus spp. as a starter culture for alkaline fermentation [41], as a source of biopreservative for food safety [45] and as a model system for the production of pharmaceutically importan
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