ERIC Number: EJ759187
Record Type: Journal
Publication Date: 2007
Pages: 6
Abstractor: Author
ISBN: N/A
ISSN: ISSN-1470-8175
EISSN: N/A
A Simple Experiment to Show Photodynamic Inactivation of Bacteria on Surfaces
Caminos, Daniel A.; Durantini, Edgardo N.
Biochemistry and Molecular Biology Education, v35 n1 p64-69 Jan-Feb 2007
New suitable approaches were investigated to visualize the photodynamic inactivation (PDI) of bacteria immobilized on agar surfaces. The PDI capacities of a cationic photosensitizer (5,10,15,20-tetra(4-N,N,N-trimethylammoniumphenyl)porphyrin) and an anionic photosensitizer (5,10,15,20-tetra(4-sulfonatophenyl)porphyrin) were analyzed on a typical Gram-negative bacterium "Escherichia coli" following two procedures. In Experiment I, the "E. coli" cells were grown as lawn on agar surface containing the sensitizers spread in a small area (10 nmol in approximately 0.6 cm[superscript 2]). After irradiation with visible light (10 min, 90 milliwatts/cm[superscript 2]), no cells were grown in the area containing the cationic porphyrin. In Experiment II, small colonies (approximately 2-mm diameter) of "E. coli" on agar were treated with a solution of sensitizer (10 nmol) and irradiated with visible light for 3 h. Overnight incubation at 37 degrees C shows a growth delay of "E. coli" colonies treated with the cationic photosensitizer. In contrast, the anionic porphyrin did not produce appreciable photodamage. These experiments could be either used in an undergraduate project for natural science advance students or used for a postgraduate practical training course. This methodology illustrates the application of PDI to treat bacteria growing as localized foci of infection.
Descriptors: Natural Sciences, Microbiology, Science Experiments, Laboratory Experiments, Science Instruction, College Science, Undergraduate Study, Graduate Study, Light, Biochemistry
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Publication Type: Guides - Classroom - Teacher; Journal Articles; Reports - Research
Education Level: Higher Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A