δ-Aminolaevulinic acid-induced porphyrin synthesis and photodynamic inactivation of Escherichia coli B.

✍ Scribed by K. Szocs; F. Gabor; G. Csik; J. Fidy

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 854 KB
• Volume: 50
• Category: Article
• ISSN: 1011-1344
• DOI: 10.1016/s1011-1344(99)00062-7

✦ Synopsis

The possibility and conditions for the induction of porphyrin synthesis by exogenous S-aminolaevulinic acid (ALA) and its applicability for the inactivation of Gram-negative bacteria Escherichiu coli R. by photodynamic therapy (PDT) have been studied. The bacteria are supplemented with ALA i n the log phase of growth, and are grown in a synthetic medium at 37°C in the dark. The efficiency of porphyrin synthesis is detected by fluorescence spectroscopy performed on the isolated bacterial cells and the medium, respectively, and compared with results of high-performance liquid chromatography (HPLC) analysis. ALA stimulates the synthesis of protoporphyrin in the bacteria by a factor of five to six, and an increased amount of the more hydrophilic derivatives with a significant contribution of mesoporphyrin by a factor of two to three is observed in the culturing medium. The optimal conditions of ALA treatment with respect to PDT are I O-l 5 min of incubation of a bacterial culture of 2 X IO' cells ml ' with (S-9) X IO-mot I ' ALA. The ALA-treated cells are irradiated by white light of 80 mW Cl11 ' under growth conditions and a decrease to 0.6% of the number of colony-forming units (CFUs ml ') is observed after 90 min of irradiation.