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Chapter V Discussion
for 90 min and at 121 o C for 15 min. Sparo et al. (2006) also reported a stable enterocin MR
99 from E. faecium. Partially purified bacteriocin appeared stable when pH was adjusted
from 4-12. These results are supported by various research findings (Moreno et al., 2003;
Sparo et al., 2006; Abriouel et al., 2006; Shin et al., 2008; Ghrairi et al., 2008).
Antibacterial activity of the partially purified bacteriocin was completely destroyed
upon treatment with proteolytic enzyme. Bacteriocin activities were not affected by lipase,
lysozyme, and catalase and the results were in accordance with the findings of Park et al.
2003; Abriouel et al. 2006; Cocolin et al. 2007 and Ghrairi et al. 2008. They identified and
characterized enterocin produced by E. faecium and reported their inactivation by proteinase
K, trypsin, α-chymotrypsin and papain, but not by lysozyme, lipase, catalase or β-
glucosidase. Among the detergents, Sodium dodecyl sulphate (SDS), Tween 80 and Tritone
X-100 stimulated bacteriocin production, which was strongly inhibited by EDTA and urea.
Similar results were observed by Ivanova et al. (2000) and Ogunbanwo et al. (2003). But,
stimulatory effect of Sodium dodecyl sulphate (SDS), Tween 80 and Tritone X-100 on
bacteriocin in playing that the detergents act as co-factors, which are required to increase the
bacteriocin production. A bacteriolytic effect was noted against Listeria monocytogenes for
the bacteriocin produced by L. casei LAM-1.
The molecular weight of bacteriocins produced by L. casei LAM-1 was ~2.5 kDa and
a single inhibition zone was observed from the partially purified bacteriocin preparations
from the strains of L. casei LAM-1, suggesting the production of only one potent bacteriocin.
Moreno et al. (2003) also reported single inhibitory zone for all bacteriocin after
electrophoresis followed by a bioassay. The molecular mass of the bacteriocin was between
2.5 and 6.2 kDa as described by Ying et al. 2011. The bacteriocin was stable under different
storage temperatures (4, 28 and 37 o C as tested up to 6 months. The molecular weight of the