Ultra low range molecular weight marker

Tricine-SDS-PAGE was performed to determine the molecular weight of partially
purified bacteriocin KT11 (Schägger and
von Jagow (1987). The ultra-low-range molecular weight marker (M.W.
1.06–26.6 kDa, Sigma-Aldrich) was used as a protein standard. A 16%
Tris-tricine gel was prepared for electrophoresis. The amount of protein in the
dialysate to be loaded into the gel was calculated as 5 μg. Dialysate
samples were dissolved in tricine loading buffer and loaded into the gel. After
electrophoresis, the gel was sliced into two pieces. One piece of the gel was
assayed for molecular weight determination of bacteriocin KT11 (Lane M and Lane
1) by staining with Coomasie blue R 250 for 3 h. The other piece of the gel
(Lane 2) was not stained and was used for a direct antimicrobial activity assay
(overlay method). To remove SDS from the second lane, the gel was washed three
times with 1% Tween 80 for 40 min (Yamamoto,
2003), transferred into a petri dish, and then overlaid with 15 mL of
soft nutrient agar (seeded with indicator test strain at 10⁶ CFU/mL).
After incubation at 37℃ for 24 h, the gel was examined for the presence
of an inhibitory zone.