Abstract:
A Bacillus megaterium 19strain isolated
from a mixture of fermented vegetable wastes, produced a bacteriocin that
displayed a wide spectrum antimicrobial activity against food-spoilage
microorganisms and possessed a bactericidal mode of action. The bacteriocin
activity against Salmonella typhimurium and Staphylococcus aureus
attained its maximum value during the mid stationary phase. Maximal bacteriocin
activity (93% growth reduction) was achieved using MRS broth, at initial
pH of 5.5-6.5 and at 30°C incubation temperature. High levels of bacteriocin
activity (up to 85% growth reduction) were detected under limited or reduced
oxygen levels. The inhibitory activity increased in mMRS broth with 4%
sucrose and (0.10%) beef extract. The bacteriocin was thermally stable
over a wide temperature range up to 100°C for 15 min and retained
its activity at acidic and neutral pH values, but not at alkaline pHs.
Full bacteriocin activity was expressed after 30 days of storage at 4°C,
for 15 min of exposure to UV light. The bacteriocin was amylase and lipase
sensitive, however, treatment with proteolytic enzymes resulted in a remarkable
stability. SDS-PAGE analysis of the partially purified bacteriocin revealed
an apparent molecular weight ranging from 3.496 to 6.512 kDa. The strain
may have a potential use as food biopreservative, because of its promising
thermostable technological properties and broad antimicrobial spectrum.
Rowaida Khalil, Yasser Elbahloul, Fatima Djadouni and Sanaa Omar, 2009. Isolation and Partial Characterization of a Bacteriocin Produced by a Newly Isolated Bacillus megaterium 19 Strain. Pakistan Journal of Nutrition, 8: 242-250.
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