Photodynamic inactivation of Escherichia coli by methylene blue and malachite green under red LED light

Revista Ambiente & Água

Marlene Soares¹  Adriane M. de Freitas¹  Guilherme K. F. Hasegawa¹  Josmaria Lopes de Morais² 

[1] Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR, Brasil, Departamento Acadêmico de Química e Biologia;Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR, Brasil, Departamento de Física;

关键词: bacteria;    cationic dye;    photodynamic therapy;   

DOI  :  10.4136/ambi-agua.1571

来源: DOAJ

【 摘 要 】

This study assessed the effectiveness of methylene blue (MB) and malachite green (MG) on photodynamic inactivation (PDI) of Escherichia coli. The photosensitizers methylene blue (1000 mol L-1) and malachite green (250 mol L-1) were activated with a red light-emitting diode (LED) lamp (max = 636 nm). Bacterial suspensions containing 106 CFU mL-1 were irradiated for 5, 10 and 15 minutes (energy density = 119.9 J cm-2, 223.9 J cm-2 and 335.8 J cm-2, respectively). The following experimental conditions were performed for each photosensitizer: no light irradiation or photosensitizer, irradiation only, photosensitizer only or irradiation in the presence of a photosensitizer. Next, serial dilutions were prepared and seeded onto PCA medium for the determination of the number of colony-forming units per milliliter (CFU mL-1). The results were subjected to analysis of variance (ANOVA) and Tukey test (P<0.05). Photodynamic inactivation using MB and MG was effective in reducing the number of E. coli. Malachite green (250 µmol L-1) photosensitization was able to achieve reductions of over 89% in the viable counts after 15 min of irradiation and methylene blue (1000 µmol L-1), at the same conditions of irradiation, showed a rate growth inhibition of 94.6%. The red LED light used has proven to be effective in the photosensitizing dyes and proved a good alternative to conventional light sources such as laser.

【 授权许可】

Unknown