Photoinactivation of bacteria in wastewater by porphyrins: bacterial β-galactosidase activity and leucine-uptake as methods to monitor the process

Carla M.B. Carvalho, Ana T.P.C. Gomes, Sónia C.D. Fernandes, Ana C.B. Prata, Maria A. Almeida, Maria A. Cunha, João P.C. Tomé, Maria A.F. Faustino, Maria G.P.M.S. Neves, Augusto C. Tomé, José A.S. Cavaleiro*, Zhi Lin, José P. Rainho, João Rocha

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)

Abstract

The increasing interest in photodynamic antimicrobial chemotherapy as a promising technology for wastewater treatment demands more efficient photosensitizers and faster methods for the monitorization of the photoinactivation process. Two sets of neutral and cationic porphyrins were used as photosensitizers for the photoinactivation of sewage bacteria. Two of the cationic porphyrins revealed to be highly active, even against Gram-negative bacteria, inactivating ca. 94-99.8% of these at 5 μM and after 270 min of irradiation with white light (9 mW cm-2). In addition, two expeditious methods for the evaluation of the bacteria photoinactivation were developed. These methods are based on β-galactosidase activity and on leucine incorporation and give an excellent relation with faecal coliform counts. The evaluation of these two descriptors of bacterial activity, directly related with bacterial abundance, is an easy and fast way to monitor the micro-organisms during the photoinactivation process.
Original languageEnglish
Pages (from-to)112-118
Number of pages7
JournalJournal of Photochemistry and Photobiology B: Biology
Volume88
Issue number2-3
DOIs
Publication statusPublished - 25 Sep 2007

Keywords

  • Faecal coliforms
  • PACT
  • PDT
  • Photoinactivation
  • Porphyrins
  • Wastewater

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