FOOD SCIENCE

Previous Articles     Next Articles

Antimicrobial Photodynamic Activity of Methylene Blue against Listeria monocytogenes Biofilms

LI Hong-ai, TANG Shu-shu, LIU Yong-qiang, DENG Xi, TANG Shu-ze, WU Xi-yang, CHEN Zhen-qiang   

  1. 1. College of Science and Engineering, Jinan University, Guangzhou 510632, China;
    2. Guangzhou Huangshanghuang Group Co. Ltd., Guangzhou 510240, China
  • Online:2014-02-13 Published:2014-03-17

RichHTML

9

PDF (PC)

317

Abstract:

The formation of Listeria monocytogenes (LM) biofilms (BF) and its photodynamic inactivation by methylene blue
(MB) were investigated. The LM BF formation process was identified by crystal violet staining, and the amount of biomass was
tested with an enzyme-linked immunosorbent assay (ELISA) plate reader at 595 nm. The inactivation effect of MB on LM BF
was verified by counting colony-forming units (CFU). Results indicated that crystal violet staining could be used to visualize and
quantify LM BF. The amount of biomass increased and the formed network structure became more complicated as the incubation
time was extended. Over 99.99% of LM BF was inactivated and colony-forming units were reduced by 4.08 (lg(CFU/mL)) after
illumination with visible light (power density 200 mW/cm2) for 30 min. LM BF were effectively inactivated by MB, and the
efficacy mainly depended on the concentration of photosesitizer and illumination time.

Key words: biofilm (BF), Listeria monocytogenes (LM), methylene blue (MB), anti-microbial photodynamic technology (APDT)