TITLE:
Analysis of bacterial growth at various distances from an antimicrobial surface
AUTHORS:
Shohei Nunose, Rie Iwai, Shujiro Okuda, Yuki Tsuchiya, Hisao Morisaki
KEYWORDS:
Antimicrobial Surface; Escherichia coli; Microculture; Biofilm
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.4 No.4,
April
19,
2013
ABSTRACT:
Antimicrobial materials
have been used in various environments. However, the activity of cells at a
distance from the antimicrobial materials has not been elucidated. In the
present study, the cell growth of Escherichia
coli NBRC 3972 was observed at different distances (0 - 300 μm) from the
antimicrobial surface under various nutrient
concentrations, from full strength nutrient broth (NB) to 1/40 NB.
Under higher nutrient concentrations, NB and 1/2 NB, no antimicrobial
effect on cell growth was observed at any distance from the surface. Under
lower nutrient concentrations, 1/10 NB and 1/40 NB, the growth of cells directly
contacting the antimicrobial surface (at 0 μm from the surface) was blocked
immediately after inoculation on the surface.
However, at distances of 100 - 300 μm from the surface, the cells grew
normally for a while, and then stopped the growth; earlier growth
discontinuation was observed for cells closer to the surface. It was suggested
that the antimicrobial agent (silver ions) is released from the antimicrobial
surface into the medium and that the diffusion of the silver ions may influence
the lag in the antimicrobial effects observed at distances away from the
antimicrobial surface. The present study reveals the possibility that
antimicrobial activity in the environments where the antimicrobial material is
used depends on the distance from the surface and the surrounding nutrient
concentrations.