Antibacterial Peptides, Probiotic Properties and Biopreservative Efficacy of Native Bacillus Species Isolated from Different Food Sources.

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
of the isolated Bacillus spp. or their ABP for application in
food biopreservation and as probiotics.